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HFS Tables of Contents: 87-187-288-188-289-189-290-190-291-191-292-192-293-193-294-194-295-195-2

Proceedings of the Human Factors Society 36th Annual Meeting 1992-10-12

Fullname:Proceedings of the Human Factors Society 36th Annual Meeting
Note:Innovations for Interactions
Location:Atlanta, Georgia
Dates:1992-Oct-12 to 1992-Oct-16
Standard No:ISSN 0163-5182; TA 166 H794; hcibib: HFS92-1
Links:Online Proceedings
  1. HFS 1992-10-12 Volume 1
    2. AEROSPACE SYSTEMS: Design, Methods, and Workload
    3. AEROSPACE SYSTEMS: Automation Effects
    5. AEROSPACE SYSTEMS: Cockpit Displays
    6. AEROSPACE SYSTEMS: Controls and Displays
    7. AEROSPACE SYSTEMS: Selection and Training
    8. AEROSPACE SYSTEMS: Aiding, Training, and Information Systems for Aviation Maintenance and Operational Environments
    9. AEROSPACE SYSTEMS: Fatigue and Stressor Effects
    10. AEROSPACE SYSTEMS: Potpourri: Displays and Space Systems
    12. AGING: Determinants of Age Differences in Cognitive Performance
    13. AGING: Assessing Age Differences in Performance Variables
    14. AGING: Designing New Technologies for Older Adults
    15. COMMUNICATION: Proven Benefits and Promises
    16. COMMUNICATION: Improved User Control of Phone Services
    17. COMMUNICATION: Improving Mediated Communication: Acoustic, Linguistic, and Visual Factors
    18. COMMUNICATION: Auditory Perception
    19. COMPUTER SYSTEMS: Keyboard Input Devices
    20. COMPUTER SYSTEMS: Handwriting, Speech, Touchscreen, and Other Input Techniques
    21. COMPUTER SYSTEMS: Cursor Control and Other Input Techniques
    22. COMPUTER SYSTEMS: Color, Menus, and Other Information Presentation Techniques
    23. COMPUTER SYSTEMS: Computer-Based Displays I
    24. COMPUTER SYSTEMS: Computer-Based Displays II
    25. COMPUTER SYSTEMS: Tools and Techniques
    26. COMPUTER SYSTEMS: Complex Systems
    27. COMPUTER SYSTEMS: Usability and Rapid Prototyping
    28. COMPUTER SYSTEMS: Design Guidelines
    29. COMPUTER SYSTEMS: Computer System Potpourri
    30. COMPUTER SYSTEMS: Designing Control Rooms for the Year 2000: New Technologies, New Techniques?
    31. CONSUMER PRODUCTS: Automotive Applications
    32. CONSUMER PRODUCTS: Warning Research
    33. CONSUMER PRODUCTS: Product Applications
    34. CONSUMER PRODUCTS: Labeling for Food and Beverages
    36. EDUCATORS' PROFESSIONAL: Educational Issues in Human Factors
    38. EDUCATORS' PROFESSIONAL: Increasing the Breadth of the Human Factors Scientist-Practitioner
    40. ENVIRONMENTAL DESIGN: Planning for Environmental Design and Follow-Up Evaluations
    42. FORENSICS PROFESSIONAL: Warnings and Hazard Prevention
    43. FORENSICS PROFESSIONAL: Real-World Problems and Practices in Forensics
    44. GENERAL SESSIONS: NAS/NRC Committee on Human Factors: Retrospect and Prospect
    45. GENERAL SESSIONS: Environmental Management: Interfaces with Human Factors
    46. GENERAL SESSIONS: Human Error and Medical Devices
    47. INDUSTRIAL ERGONOMICS: Lifting/Manual Material Handling
    48. INDUSTRIAL ERGONOMICS: Strength and Capacity Issues
    49. INDUSTRIAL ERGONOMICS: Occupational Ergonomics
    50. INDUSTRIAL ERGONOMICS: Strength/Potpourri
    53. INDUSTRIAL ERGONOMICS: Back/Trunk Ergonomics
    54. INDUSTRIAL ERGONOMICS: Hand Ergonomics I
    56. INDUSTRIAL ERGONOMICS: Hand Ergonomics II
    57. INDUSTRIAL ERGONOMICS: Hand Ergonomics III

HFS 1992-10-12 Volume 1


Everybody Knows -- Or Do They? BIB --
  Kenneth R., Sr. Laughery
List of Workshops BIB 1

AEROSPACE SYSTEMS: Design, Methods, and Workload

A Framework for Design Traceability BIBA 2-6
  B. J. Barnett; C. J. Arbak; J. L. Olson; L. C. Walrath
Methods are needed for implementing findings of theoretical research early in the design phase and tracing them through to final designs. This paper describes one such approach in applying what is known about cognitive psychology, human factors, and development techniques to interface design. The basic technique used to provide a design framework was an adaptation of the Quality Function Deployment (QFD) house of quality. This paper describes the QFD structure and how it was adapted to provide that critical link between theoretical research findings and resulting interface design concepts. The discussion focuses on three topics: basic concepts within the house of quality, the house of quality adapted for interface design, and application to the design process. A number of benefits are realized from use of this approach. First, it describes directly the relationship between human processing characteristics, design requirements, and design solutions. Second, it characterizes the nature of conflicts among alternative design solutions. Third, it indicates areas of potential applied research. Finally, it provides a single, hierarchical construct that carries through from the initial conceptual design to final product evaluation. The benefit of this approach to interface design is that a broad spectrum of theoretical and experimental research is summarized into a manageable design tool, which may provide insights to human factors practitioners, design engineers, and subject matter experts alike.
Electronic Checklists: Implications for Decision Making BIBA 7-11
  Kathleen L. Mosier; Everett A. Palmer; Asaf Degani
Checklists are a way of life on the flight deck, and, undoubtedly, are indispensable decision aids due to the volume of technical knowledge that must be readily accessible. The improper use of checklists, however, has been cited as a factor in several recent aircraft accidents (National Transportation Safety Board, 1988, 1989, 1990). Solutions to checklist problems, including the creation of electronic checklist systems which keep track of skipped items, may solve some problems but create others. In this paper, results from a simulation involving an engine shutdown are presented, and implications of the electronic checklist and "memory" checklist are discussed, in terms of potential errors and effects on decision making. Performance using two types of electronic checklist systems is compared with performance using the traditional paper checklist. Additionally, a "performing from memory" condition is compared with a "performing from the checklist" condition. Results suggest that making checklist procedures more automatic, either by asking crews to accomplish steps from memory, or by checklists that encourage crews to rely on system state as indicated by the checklist, rather than as indicated by the system itself, will discourage information gathering, and may lead to dangerous operational errors.
Predictive Workload Models and Multiple-Task Performance BIBA 12-16
  Kenneth J. Sarno; Christopher D. Wickens
The goal of the present study was to evaluate three workload models, VACP (Aldrich, Szabo, and Bierbaum, 1988), TLAP (Parks and Boucek, 1988), and WINDEX (North & Riley, 1988), in terms of how well they account for task performance results gathered from a laboratory experiment. The models are discussed in terms of their treatment of five timesharing issues: 1) the nature of workload components (mutually exclusive or partially overlapping); 2) the utility of distinguishing between cognitive processing codes; 3) classifying voice response (psychomotor function or separate component; 4) qualitative vs. quantitative coding of task demands; and 5) the utility of an overload red-line. A correlational analysis was performed on model predictions versus actual performance for 16 different task loading conditions, to evaluate each of the three workload models. All three models did a good job of predicting performance differences across conditions, accounting for between 61% and 77% of the variance, with the TLAP model providing the best prediction. In addition, a hybrid model was developed (using the "optimal" assumptions concerning the five timesharing issues) which accounted for 85% of the variance. The results are discussed in terms of the viability of the assumptions made by each of the models with respect to the five timesharing issues.
Establishing Workload Acceptability: An Evaluation of a Proposed KC-135 Cockpit Redesign BIBA 17-21
  Justin Rueb; Michael Vidulich; John Hassoun
Workload assessment has become a common part of system evaluation. Workload assessment is an important adjunct to performance measurement because the operator is sometimes flexible enough to disguise excessively demanding systems by expending additional effort to overcome optimal information processing limits. This is often referred to as the problem of determining a "workload redline." The present paper recounts an evaluation of a proposed redesign of the KC-135 tanker aircraft cockpit. The current KC-135 cockpit has three crew positions: pilot, copilot, and navigator. As part of a proposed redesign, modern automation capabilities to replace the navigator were considered. Ten operational KC-135 crews and two KC-10 crews were studied while performing missions of differing levels of workload in a high-fidelity simulator. Three main classes of data relevant to the redline issue were collected: Performance data, Subjective Workload Assessment Technique (SWAT) ratings, and Subjective WORkload Dominance (SWORD) ratings. Evaluation of the performance results demonstrated that the redesigned cockpit could be flown in accordance to regulations. This was a necessary first step, but could not ensure that acceptable workload had been obtained. Taken together, the SWAT and SWORD results strongly suggested that acceptable performance can be achieved at acceptable levels of workload. In conclusion, the present study is a prototypical example of using available assessment tools to determine system acceptability. These tools should be useful for many other system evaluations.

AEROSPACE SYSTEMS: Automation Effects

Development and Validation of a Scale of Automation-Induced "Complacency" BIBA 22-25
  Indramani L. Singh; Robert Molloy; Raja Parasuraman; Saroj Parasuraman
In the present studies, a scale was developed for measuring attitudes toward automation technology that reflect a potential for complacency. In the first, developmental study, a 20-item questionnaire consisting of statements concerning various aspects of automation was administered to 139 undergraduates at Catholic University. Factor analysis of the complacency potential rating scale (CPRS) revealed five independent factors, namely: general, confidence-, reliance-, trust-, and safety-related complacency. The internal consistency reliability coefficients of the five factors and the scale as a whole were found to be high, and the scales revealed satisfactory test-retest reliabilities. The pattern of correlations among CPRS score, age, gender, computer use, and computer experience were consistent with previous studies examining attitudes toward microcomputer usage (Igbaria and Parasuraman, 1991). In the second, validation study, the 20-item CPRS was cross-validated on a sample of 175 undergraduate students at Drexel University. Factor analysis similarly revealed five factors with high alphas. The results indicate that the potential for complacency can be evaluated by assessing attitudes towards automation technology.
Mode Error in Supervisory Control of Automated Systems BIBA 26-29
  Nadine B. Sarter; David D. Woods
Mode errors are one kind of breakdown in human-computer interaction. The concept was developed originally in the context of relatively simple reactive computerized devices such as word processors. When a device possesses multiple modes, where something is done one way in one mode and another way in another mode, there is increased potential for erroneous actions. In this paper we extend and expand the concept of mode error to supervisory control of automated resources in event-driven situations such as pilot interaction with cockpit automation. In this type of situation, the state of the automated system can change in response to either operator input, situation factors or system factors. This creates complexities in tracking system mode changes over time, surprises created by "uncommanded" mode changes, and the possibility of errors of omission as well as commission in managing multiple system modes. Progress in our understanding of mode error in the context of highly automated systems is important in our ability to develop effective countermeasures for mode-related problems in human-computer cooperation.
Automation Effects in the Cockpit: A Low-Fidelity Investigation BIBA 30-34
  Coleen Thornton; Curt Braun; Clint Bowers; Ben B., Jr. Morgan
The effects of automation and task difficulty on flight performance, subjective and objective workload, and a problem solving task were investigated in a low fidelity flight simulator. Forty-eight, two-person crews flew two forty-five minute scenarios that required the crew to select and obtain relief supplies for delivery to a disaster site. Two levels of automation (i.e., presence or absence of an autopilot) and two levels of task difficulty (i.e., presence or absence of wind and turbulence) were combined to yield a 2 x 2 design. Twenty-four crews performed in both levels of automation and one level of task difficulty. Results indicated that although crews in the automated condition reported less subjective workload, only one of the three measures of flight performance was affected by automation. In contrast, objective workload, as measured by performance of a secondary task, was increased for the pilot in the automated condition. In addition, under high task difficulty, problem solving was worse in the automated condition than in the manual condition. The results are discussed in terms of their support of earlier hypothesized effects of automation in the cockpit.
The Effects of Mixed-Fleet Flying of the Boeing 737-200 and -300 BIBA 35-39
  Elizabeth A. Lyall
The performance effects of pilots concurrently flying two derivatives of the Boeing 737 (-200 and -300) were assessed at America West Airlines using data gathered in flight and from a pilot survey. The B737-200 and -300 differ in levels of flightdeck automation. An activity analysis methodology was used to gather the in-flight data. Seven of the activities observed were used as dependent measures in the analyses. It was found that the pilots did significantly more hand-flying when they were on a trip in which they flew both the -200 and -300 (a mixed trip), than when they only flew one plane type (a pure trip). Also, on mixed trips where the pilots flew the -200 and then the -300: after they switched into the -300 they engaged in more flight-relevant talking and they looked out the window less than pilots who flew the -300 and then the -200, or a pure trip. These were the only significant results related to mixing the plane types. It was concluded that the airline environment studied did not show significant detrimental performance effects due to mixed-fleet flying. This was supported by the survey data where 75% of the pilots responded that it is alright to mix the planes. Implications of mixed-fleet flying on training and scheduling are discussed, and the recommendations made to America West are presented.


Situation Awareness: Modelling, Measurement, and Impacts BIB 40-42
  Carol Lynn Judge; James B. Bushman; Michael A. Vidulich; Michael R. Houck; Frederick M. Siem; J. Raymond, Jr. Comstock; Cynthia O. Dominguez


The Use of a Background Attitude Indicator to Recover from Unusual Attitudes BIBA 43-47
  Kristen K. Liggett; John M. Reising; David C. Hartsock
The purpose of this study was to evaluate various cues on a background display format that depicted attitude information. A combined head-down display format was evaluated where the central rectangular area focused on tactical information and the background border presented attitude information. The attitude information, in essence, framed the tactical display format. A comparison was conducted among variations of the original background attitude indicator (BAI) created by General Dynamics personnel. Three types of cues were investigated: color shading, color patterns, and pitch lines with numbers. These cues were tested individually and in combination with one another. Results showed that in terms of initial input time, the combination of color shading and color patterns performed the best.
The Utility of a Ghost Horizon and Climb/Dive Ladder Tapering on a Head-Up Display BIBA 48-51
  Lisa F. Weinstein; William R. Ercoline; D. Foster Bitton
As part of an Air Force effort to standardize HUD symbology, an unusual attitude recovery task was employed to investigate the utility of a cue, the ghost horizon, that indicates the direction of the actual horizon when the climb/dive ladder horizon line is not within the HUD field of view. Six HUD-experienced and 6 non-HUD-experienced military pilot subjects were used to determine whether there was improvement, with the ghost horizon, in ability to recover from nose-down unusual attitudes in a flight simulator. The ghost horizon was evaluated with 3 different climb/dive ladder line configurations (tapered, non-tapered, reverse tapered). In terms of accuracy of the initial stick input, the ghost-horizon configurations resulted in significantly better performance (about 11% better) than did the non-ghost-horizon configurations. The ghost horizon had no effect on initial stick input reaction time or total recovery time. The climb/dive ladder line taper configuration did not affect accuracy, initial stick input reaction time, or total recovery time. Subjective data indicated that the pilots did not have a strong preference for any of the configurations. These findings suggest that the ghost horizon is a useful aid to unusual attitude recovery performance, and may reduce spatial disorientation.
Comparison of a Head-Up Display Evaluation in Ground and Flight Simulation BIB --
  Valerie J. Gawron; Thomas Hughes; John Hassoun; Randall Bailey
A God's Eye (Exocentric) versus Pilot's Eye (Egocentric) Frame of Reference for Enhanced Situational Awareness BIB --
  Woodrow Barfield; Tom Furness; Craig Rosenberg; Alex Han

AEROSPACE SYSTEMS: Controls and Displays

"Soft" Controls for Hard Displays: Still a Challenge BIBA 52-56
  Asaf Degani; Everett A. Palmer; Kristin G. Bauersfeld
Future trends in design of controls and displays for cockpit sub-systems (electrical, pneumatics, fuel, etc.), will undoubtedly focus on replacing dedicated "hard" controls with reconfigurable "soft" controls depicted on the sub-system schematic display. This concept would allow for direct manipulation of mechanical components via the display. The case study reported here discusses the approach, redesign, and evaluation of soft controls and multi-functional displays for the Advanced Concepts Flight Simulator (ACFS), a two-engine, "generic" airliner. The redesign effort focused on the input interface (a touch sensitive screen), the display concept, and improving "navigation" among sub-system displays. The paper concludes with a summary of questionnaire data and comments of 26 airline pilots who flew a four-segment mission in the simulator. The subjective results indicated that pilots favored the direct manipulation concepts and the ability to link alerts, procedures, and configuration tasks. However, the technology used to support this concept still requires improvements.
The Use of 3D Auditory Perspective and Perspective-Auditory Display Formats for Directional Judgment Tasks BIB --
  Woodrow Barfield; Craig Rosenberg; Mike Cohen
Multi-Modal Cockpit Warnings: Pictures, Words, or Both? BIBA 57-61
  S. J. Selcon; R. M. Taylor; R. A. Shadrake
This paper examines the requirement for, and benefits of, multi-modal information presentation in cockpit warning systems. It also attempts to provide an account of the nature and levels of processing involved when information from one source is integrated with a supposedly redundant additional source to provide a performance gain in choice reaction time (RT) tasks, and its applicability to other cockpit systems. An experiment is described which used warning/caution 'icons' (pictorial representations of danger situations) and verbal warning messages, both singly and in combination. The visual icons were generated by RAF aircrew, using an iterative design process, as being meaningful pictorial representations of real-world warnings. Subjects were required to identify whether the situations presented warnings i.e. high priority/immediate action or cautions i.e. low priority/immediate awareness. The results obtained showed a significant decrease in response latencies when correlated bi-modal information was given as compared to the uni-modal conditions. The high level of abstraction of these icons strongly implied that the performance gains occurring must be as the result of the integration of 'information' rather than 'data'. Subjective Situational Awareness Rating Technique (SART) scores also showed that benefits may also be accrued through reduced workload and increased depth of understanding. The results of these experiments are considered in terms of current Information Processing and Neural Network theories and an attempt to provide a cognitive model of this integrality effect is also described.

AEROSPACE SYSTEMS: Selection and Training

Topographic EEG Correlates of the Basic Attributes Test for Air Force Candidate Selection BIBA 62-65
  M. B. Sterman; D. Kaiser; C. Mann; J. Francis
Topographic EEG data were collected from subjects performing on three selected subtests of the Basic Attributes Test. Spectral analysis focused on the 8-12 Hz frequency band showed differences in cognitive demand among subtests, and individual differences in cognitive resource utilization which were related to performance.
Analysis of En Route Air Traffic Controller Team Communication and Controller Resource Management (CRM) BIBA 66-70
  Thomas L. Seamster; John R. Cannon; Richard M. Pierce; Richard E. Redding
This analysis of en route air traffic controller communication was part of a larger Federal Aviation Administration effort to redesign the training program for en route air traffic control. This presentation concentrates on the analysis and results of the team communications as they relate to Controller Resource Management (CRM). The team controller communication takes place between the radar controller and the radar associate controller as they perform their related tasks in the management of the sector air traffic. This study used an inductive approach to look at communication frequencies across different types of controller teams. The controller teams were manipulated by using different combinations of expert, intermediate, and novice controllers, and these teams were compared under moderate and heavier workloads while managing simulated air traffic. The team communications were coded and analyzed at the speech turn level. Observations, situational inquiry, and answers supplying information combined to make up over half of the speech turns used by the controllers in team communication. A more detailed analysis by controller position and performance identified communication frequencies for the better performing sessions. These results are interpreted in relation to a recent mental model of the en route air traffic controller and are further explained based on results of a study of live traffic team communication. The discussion explores the roles of the team members in maintaining effective CRM.
An Evaluation of an Altitude Awareness Study BIBA 71-75
  Thomas M. Granda; Patricia J. Vingelis
Because of the increase in altitude deviations at USAir during the spring and summer of 1990, an Altitude Awareness Program was instituted in September of 1990. The program emphasized cockpit altitude awareness procedures for pilots to utilize when handling altitude clearances and pilot altitude awareness in general. The program included a data collection and analysis effort involving voluntary pilot reported altitude deviations and potential deviations. USAir's program was subsequently expanded by the Federal Aviation Administration (FAA) to include the air traffic controllers at six mid-Atlantic facilities. The study, like the program, focused on a team approach and a positive data collection environment. The study results show that there was a significant difference between the average monthly rates of FAA reported altitude deviations concerning USAir flights for the thirteen month period prior to initiation of the Altitude Awareness Program and the fourteen month period after the program started. An error classification analysis showed that most of the pilot and controller errors were identified as information processing, task prioritization, and decision making errors.
Electroencephalographic Correlates of Psychological Defense BIBA 76-80
  M. B. Sterman; C. A. Mann; H. R. Eriksen; M. Olff; H. Ursin
The Kragh tachistoscopic method for measuring psychological defense mechanisms ("Defense Mechanism Test" -- DMT) has been claimed to be valid for selection of personnel for really dangerous tasks. The method consists of presenting a stimulus picture at initial exposure times that are too short for perception. To test whether this perceptual disturbance arises from an aberrant cognitive response to the situation, we studied the magnitude, topographic distribution, and temporal modulation of spectral density in the 8-12 Hz EEG frequency band during DMT testing in 22 male and 2 female active duty US Air Force personnel. Personnel with high defense mechanisms had significantly more attenuation of the 8-12 Hz activity during stimulus exposure than low defenders, implying an increased level of cortical activation. Personnel with low defense scores relax faster than those with high scores. The differences seem to occur even before threat is reported. High defense seems to require more and longer lasting data processing which may be too costly in dangerous situations.

AEROSPACE SYSTEMS: Aiding, Training, and Information Systems for Aviation Maintenance and Operational Environments

Aiding, Training, and Information Systems for Aviation Maintenance and Operational Environments BIBA 81
  William T. Shepherd
This session will demonstrate three technology-based tools to improve human performance in aviation environments. All presenters will use a projection display to show real-time examples of aiding or training and/or on-line documentation systems. As an added feature of this session a Hypermedia diskette of the session will be distributed to all session attendees. The diskette will contain the session papers, with appropriate hypermedia links within and among the papers. The diskette will be described in the Johnson, et al. presentation on integrated information systems.
Human Factors Challenges in Aviation Maintenance BIBA 82-86
  William T. Shepherd
The FAA Office of Aviation Medicine has been conducting a research program for the past two years dealing with human factors issues in aircraft maintenance and inspection. As part of this program a series of workshops have been held with participation of a broad spectrum of air carrier industry representatives. These representatives, ranging from hanger floor technicians to vice-presidents, have identified a series of issues or challenges which present their most formidable human factors problems. The FAA research program has been designed to address these challenges. This paper describes five of these challenges and offers guidance on methods for dealing with them.
Integrated Information for Maintenance Training, Aiding, and On-Line Documentation BIBA 87-91
  William B. Johnson; Jeffrey E. Norton; Leonard G. Utsman
Today's portable computer systems have the power, memory, and storage to support a broad spectrum of capabilities in maintenance environments. The computer hardware is a minor part of the success equation when compared to the intricacies of writing software and other design activities like knowledge base creation and interface development. The cost vs. benefit analysis is more likely to favor new technology when the same system can be used across multiple functions within a technical environment. The integration of training, job aiding, and on-line information is discussed in this paper. The software technologies of intelligent tutoring, expert-system job aiding, and multimedia information storage/retrieval will be described. Example systems are from the aviation and electric power generation maintenance environments.
Computer-Simulated Aircraft Inspection Tasks for Off-Line Experimentation BIBA 92-96
  K. A. Latorella; A. K. Gramopadhye; P. V. Prabhu; C. G. Drury; M. A. Smith; D. E. Shanahan
Previous research on civil aircraft inspection and maintenance, (e.g., Shepherd, 1990) has shown the potential for human factors interventions. However, for specific interventions to be tested and detailed models to be developed a system for rapid, off-line experimentation is required. Two computer-simulated inspection tasks are described, one for non-destructive inspection and the other for visual inspection. Both systems have been used for experiments, the brief results of which are presented. Future extensions to the programs, and other experiments under way, are discussed.
An Empirical Evaluation of Tools to Aid in Enroute Flight Planning BIBA 97-101
  Charles F. Layton; Philip J. Smith; C. Elaine McCoy; Thomas E. Bihari
After a number of background studies (including surveys, a simulator study, and interviews with commercial air traffic controllers, dispatchers, and pilots), several design concepts have been developed to guide in the design of tools to aid in enroute flight planning activities. Alternative versions of these tools have been implemented in the Flight Planning Testbed (FPT), a part-task simulation environment for studying interactions with flight planning tools. This testbed, which runs on a Macintosh IIfx, presents scenarios and records all interaction with the operators. Thirty commercial airline pilots participated in a between-subjects experiment involving three alternative system designs and four flight planning scenarios. The results provide some very interesting insights into planning strategies and the effects of cognitive tools on those strategies.

AEROSPACE SYSTEMS: Fatigue and Stressor Effects

Sleep and Flight Duration Effects on the Subjective Fatigue of Pilots during Operation Desert Storm BIBA 102-105
  Kelly J. Neville; Jonathan French; Roger U. Bisson; Patricia A. Boll; William F. Storm
Subjective fatigue of 11 C-141 pilots serving in the United States Air Force Military Airlift Command (MAC) during the Desert Storm campaign was assessed in a 30-day field study. Subjective fatigue measures were obtained from pilots at the beginning and end of each duty day using the Profile of Mood States (POMS) fatigue dimension. Also, a 7-point fatigue rating was recorded every 4 hours. The two fatigue measures were each evaluated with respect to (1) 48-hr cumulative flight time, (2) 48-hr cumulative sleep time and (3) 30-day cumulative flight time. The data indicate that at least 15 hours of sleep per 48-hr time period is needed to avoid pilot fatigue. Recent flight time was also found to be related to subjective fatigue, but this relationship seems rooted loss of sleep during long flights. Cumulative 30-day flight time, which is the measure currently used to regulate flight hours, was not related to increases in subjective fatigue.
Effects of Long-Term Exposure to High G on Blood Oxygen Saturation and Performance BIBA 106-110
  Kathy McCloskey; Stephen Popper; Daniel Repperger; Lloyd Tripp
The effects of long term exposure to a high g simulated aerial combat maneuver (SACM, or alternating peaks of +4.5Gz to +7.0Gz) were examined using blood oxygen saturation (SAO2) levels and performance measures (RTs, error rates, and comfort ratings). Four different anti-g protection device configurations were evaluated: the standard issue CSU-13 B/P anti-g suit, an experimental retrograde inflation anti-g suit (RIAGS), the RIAGS with capstan sleeves, and the RIAGS with occlusion cuffs. Overall, RIAGS with sleeves allowed subjects to endure much longer times at high g. However, when SAO2 levels were correlated with time to exhaustion, there were no differences between protective suit configurations. RIAGS with sleeves appeared to lead to a slower decrement in blood oxygen saturation levels during long term exposure, allowing subjects to remain at high g longer. It was also shown that SAO2 levels "rebounded" to some extent before each of the next +7Gz onsets, but when subjects approached their endurance limits this rebound effect diminished. It seems the longer subjects endured high g, the less able they were to physiologically compensate. The simplest task condition showed an increased in RT when subjects neared their exhaustion point. The more difficult task conditions showed too much variability in RTs to discern any performance patterns. It seemed enough effort and attention was directed to the task to maintain stable performance in the easy condition, but was not enough to maintain performance in the more difficult conditions. Error rates also increased as subjects neared exhaustion, as expected. However, error rates were sensitive to differences among suit configurations, whereas RTs were not. Error rates covaried with time at SACM and comfort ratings. In summary, subjects wearing RIAGS with sleeves withstood high g for longer periods of time, had less error in their performance, and rated the suit most comfortable.
The Prediction of Cognitive Performance Degradations during Sustained Operations BIBA 111-115
  Anna L. Rowe; Jonathan French; Kelly J. Neville; Douglas R. Eddy
Opportunities for fatigue related accidents are greatest when extended duty cycles must be maintained. A means to plan for the influence of fatigue would be useful to best utilize crew resources. Equations were derived to predict performance degradations associated with fatigued cognitive abilities. During a 30-hour sleep deprivation study, nine male subjects were required to perform a 45-minute cognitive performance battery every 120 minutes. Plasma melatonin levels also were obtained. Cognitive performance measures sensitive to fatigue were determined and used to derive composite response time and accuracy scores. The equations that best described the composite scores included a linear component (hours awake weighting) and a circadian component (melatonin weighting). The respective prediction equations accounted for 33% of the variance in response time performance (p < .0001) and 18% of the variance in accuracy performance (p < .0005). Tests on the beta weights indicated that accuracy predictions were more enhanced by the circadian component than were those for response time. This work represents a mathematical description of fatigued performance that is sensitive to circadian cycles and requires minimal input data. The results might be used to recommend the best crew rest times and when additional crew should be employed as individual performance falls below critical thresholds during sustained operations.
Operational and Human Factors Implications of Physiological Deconditioning in Long Duration Spaceflight BIBA 116-120
  Mark A. Guidi; Dwight Holland
A major factor in determining the success of any manned long duration space mission will be how well the human body can endure the microgravity environment. Data collected from long duration space missions conducted by both the United States and the former Soviet Union have shown that almost every system in the human body is adversely affected by microgravity. These adverse affects, taken individually or in concert, can have operational implications for a long duration space mission. Data collected to date indicate that significant human factors complications could arise due to the deconditioning of the musculoskeletal, cardiovascular and hematological systems that occur in a microgravity environment, resulting in decrements in overall astronaut performance. This paper examines some of these deconditioning effects, their immediate operational implications and possible countermeasures.

AEROSPACE SYSTEMS: Potpourri: Displays and Space Systems

Distance Metrics in Multifunction Displays BIBA 121-125
  Karen S. Seidler; Christopher D. Wickens
The need to scan and integrate sources of information in multifunction displays (MFDs) forces consideration of the relationships between the screens in the database. This paper develops a spatial metaphor that can be used to explore these underlying relationships. Three metrics of distance -- navigational (the number of choice points lying between screens), organizational (the structure of the hierarchy), and cognitive (the user's mental representation of information relatedness) -- were identified and empirically examined by using a simulated, hierarchically arranged, menu-driven MFD in an aviation context.
Anthropomorphic Teleoperation: Controlling Remote Manipulators with the DataGlove BIBA 126-130
  Joseph P., II Hale
A study was conducted to assess the capabilities and limitations of the DataGlove, a lightweight glove input device that can output signals in real time based on hand shape, orientation, and movement. The DataGlove was used as an input device to control the Proto-Flight Manipulator Arm (PFMA), a large telerobotic arm with an 8-foot reach. Twelve volunteers (six males and six females) participated in a 2x3(x2) full-factorial experiment in a simple retraction, slewing, and insertion task. Two within-subjects variables, time delay (0,1, and 2 seconds) and PFMA wrist flexibility (rigid/flexible) were manipulated. Gender served as a blocking variable. Retraction, insertion, and slew times, as well as total task time were collected as the dependent variables. An analysis of variance found a main effect of time delay for slewing and total task times. A post hoc Newman-Keuls pairwise comparison of the means was performed for the significant effects. Slew times with no time delay were significantly faster than slew times with either 1- or 2-second time delays. Total task time with no time delay was significantly faster than total task time with a 2-second time delay. PFMA wrist flexibility had no significant main effect on the ability of the subject to accurately and effectively operate the PFMA with the DataGlove. It was concluded that the DataGlove is a legitimate teleoperations input device that provides a natural, intuitive user interface and should be considered in future trades in teleoperation systems' designs.
Viewing Evaluation of the Two Cupola Locations on Space Station Freedom (SSF) BIBA 131-135
  Sheryl L. Stealey; Frances Mount
Analyses are continuing in the Man-Systems Division of NASA Johnson Space Center, on the restructured Space Station Freedom (SSF). Viewing requirements for the SSF indicate that assembly and extravehicular crew operations should be viewed by direct means whenever possible. To analyze the extent to which the Cupola meets this requirement, positions on the port side of Node 2 and the zenith side of Node 1 were evaluated. These analyses utilized the tasks from Mission Build (MB) 6 through 16 to investigate these two Node positions. The analyses conducted were based on a 4-position rating scale (Excellent, Good, Marginal, and Inadequate) which solicited data from both expert crewmembers and specialists in the field of robotic assembly operations. To remedy the potential direct viewing problems identified through this investigation, it was recommended that additional camera ports be placed along the truss and on the modules to provide indirect orthogonal viewing for berthing operations and pressurized module attachment. It was also recommended that additional Node positions be investigated to determine the optimal location for the Cupola based on crew considerations, direct viewing requirements, lighting issues, and operational tasking issues.
Test and Evaluation of a Zero-G Treadmill Restraint System BIBA 136-140
  Glenn K. Klute; Albert Rodriguez
Manned spaceflight missions result in human exposure to reduced gravity environments, during which the human body undergoes some pronounced physiological changes. Exercise has been identified as a practical and operationally acceptable countermeasure to the physiological responses to "zero-gravity". At the National Aeronautics and Space Administration's Johnson Space Center, a new treadmill is under development for use on Shuttle flights. One of the main challenges of this project is the development of an effective restraint system. The restraint system must place a body weight load on the subject while the subject exercises in zero-gravity. Additionally, the restraint system must allow the subject to exercise in zero-gravity at various percent grades (treadmill slopes). This paper discusses the restraint system of a prototype treadmill and zero-gravity test results. The results indicate the manually operated, prototype restraint system has some limitations and that a real-time feedback system utilizing a servo operated adjustment mechanism would significantly enhance performance.


Human Factors Research in Response to the National Plan for Aviation Human Factors BIB --
  James P. Jenkins; Sam A. Morello; Vic Lebacqz; John Wiley; William T. Shepherd

AGING: Determinants of Age Differences in Cognitive Performance

Memory Performance as a Function of Age, Reattribution Training and Type of Mnemonic Strategy Training BIBA 141-145
  Marilyn L. Turner
This experiment investigated whether mnemonic strategy training, occurring over a two-month period, would result in improved memory performance when combined with reattribution training. It was also hypothesized that the old and young may differ in their ability to perform nonverbal and verbal mnemonics. Therefore, age-related differences in memory performance were investigated as a function of whether the mnemonic was verbal (Alphabet Search Method) or non-verbal (Method of Loci), and whether or not reattribution training was combined with mnemonic training. Subjects were 34 old (Mean age = 69.5) and 34 young (Mean age = 22.8) adults. Memory performance was measured on the California Verbal Learning Test, the Nelson-Denny Vocabulary Test, the Beck Depression Inventory and four memory span tasks, prior and following a two-month period of weekly mnemonic strategy training sessions. A third of the subjects were trained with the Method of Loci, a third with Alphabet Search, and the remaining third served as the waitlist control group. In addition, half the young and old subjects from each mnemonic group did, and half did not, participate in a reattribution training workshop. Results clearly showed that mnemonic strategy training was useful for the old and young. However, the combination of reattribution and mnemonic strategy training only enhanced old, not young, memory scores when the type of strategy required verbal skills (Alphabet Search). The implication was that mnemonic strategy training may be more effective for the old if combined with reattribution training, and, if the mnemonic requires verbal rather than non-verbal skills.
Age-Related Effects in Consistent Memory Search: Performance is the Same but What about Learning? BIBA 146-150
  Brian P. Cooper; Mark D. Lee; Robert E. Goska; Marjo M. Anderson; Paul E., Jr. Gay; Lynne Ann Fickes; Arthur D. Fisk
Two experiments were conducted to investigate the mechanisms which underlie the learning in consistently mapped (CM) memory search. In Experiment 1, old and young adults were trained in both CM and variably mapped (VM) category search. The training results replicate previous findings by Fisk and Rogers (1991). Even though older adults are initially at a disadvantage relative to young adults, the comparison times of young and old adults are near zero after CM training. For VM, older adults remain at a disadvantage relative to younger adults, even after extensive training. A full reversal manipulation was implemented in Experiment 2 to investigate the learning in memory search. Initially, the young subjects were less affected by the full reversal condition compared to the performance of the older adults. However, older subjects quickly recovered and both young and old were performing at trained CM levels within 60 trials of additional practice. These results suggest: (a) attention is not being trained in CM memory search; (b) automatic category activation does not contribute much, if at all, to the performance improvement in memory search; and (c) age-invariant learning mechanisms account for performance improvement in CM memory search.
An Examination of the Adult Age Differences on the Raven's Advanced Progressive Matrices BIBA 151-155
  Renee L. Babcock
The purpose of the current project was to examine the nature of the age-related differences on the Raven's Advanced Progressive Matrices (APM). Three components were hypothesized to be involved in correctly solving the APM problems. These included a rule-identification component, a rule-application component (involving a one-rule spatial transformation), and a rule-coordination component. The project was designed to examine the influence of each of the hypothesized components on the age-related variance on the APM. Two tests presumed to measure each hypothesized component were presented to 183 adults between the ages of 21 and 83. Hierarchical regression analyses indicated that although all of the hypothesized components accounted for a significant amount of the variance on the APM (approximately 50% each), only performance on the tasks measuring rule application accounted for a unique proportion of the age-related variance on the APM. Implications of the results in regards to following symbolic instructions in assembly of objects and in driving are discussed.
Effects of Aging on Subjective Workload and Performance BIBA 156-160
  Douglas L. Boyer; Jay G. Pollack; F. Thomas Eggemeier
Demographics indicate that the population in the United States and other industrialized nations is growing older, and that the number of older workers and systems users can be expected to increase substantially over the next several decades. In order to assess possible differences between age groups the mental workload experienced by older adults as compared to that experienced by younger adults was investigated. Two tasks were utilized to assess short term memory (continuous recognition) and psychomotor (first-order unstable tracking) performance. The workload of each task was assessed with the Subjective Workload Assessment Technique (SWAT). Memory task performance measures and subjective workload ratings indicated a decrement in performance and an increase in workload for the older group relative to the younger group. Psychomotor task performance measures and subjective workload ratings indicated no difference between the age groups. It is hypothesized that the memory task makes greater demands on central processing resources than the psychomotor task used in this study. In support of this hypothesis, an analysis of the changes in ratings on the individual SWAT dimensions of time, mental effort and psychological stress revealed that an increase occurred only on the mental effort dimension for the memory task. This study implies that designers should 1) reduce or provide design features that lessen memory laden task performance for older workers, and 2) give more weight to the reduction of central processing resource requirements in trade-off studies.

AGING: Assessing Age Differences in Performance Variables

Manual Performance of Older and Younger Adults with Supplementary Auditory Cues BIBA 161-165
  Richard J. Jagacinski; Neil Greenberg; Min-Ju Liao; Jian Wang
Subjects attempted to perform the same manual movement pattern on repeated trials using a visual display of error. Additionally, some subjects heard a tone that was proportional to either the position or velocity of the ideal movement pattern. With the tone, both older and younger adults demonstrated increased anticipation in the form of an increased correlation of their movement pattern with the ideal velocity pattern. However, males exhibited this effect most with the tone that was proportional to ideal velocity, and females, with the tone that was proportional to ideal position. The benefit of the auditory displays did not carry over after they were withdrawn. These results demonstrate one technique for improving perceptual/motor performance. Although older adults exhibited a longer effective time delay, the older and younger adults benefitted from the additional cues to comparable degrees.
Age Changes in Speed and Accuracy of Hand Movements: The Baltimore Longitudinal Study of Aging BIB --
  George Erich Brogmus; Max Vercruyssen; Alan T. Welford; James L. Fozard; Lisa N. Hashimoto
The Effects of Age and Target Location Uncertainty on Decision Making in a Simulated Driving Task BIBA 166-170
  Thomas A. Ranney; Lucinda A. S. Simmons
Spatial localization has been identified as an age-sensitive process in selective attention. Because visual search in driving involves uncertainty concerning the location of information necessary for maneuvering decisions, an experiment was conducted to examine the effects of age and target location uncertainty on a simulated driving task. Seventeen younger subjects (aged 30 to 45 years) and 13 older subjects (aged 65 to 75 years) completed three tasks including two reaction-time tasks and a simulated driving task. The reaction-time tasks included three conditions (simple left, simple right, and two-choice) in a laboratory and in a stationary vehicle. The simulated driving task was conducted on a closed driving course while subjects sat in a stationary vehicle. Subjects were required to select one of two lanes using information presented either on a changeable-message sign or on traffic signals. In the high-certainty condition, subjects were told where to look for relevant information; in the low-certainty condition, they were told that information could appear in either place. Response times were measured from sign or traffic signal onset to the subject's activation of the vehicle turn signal. The results indicated small non-significant differences between age groups for the reaction-time tasks. Significant age-related differences were found in the simulated lane-selection task. Older subjects were 15% slower overall than the younger subjects. Uncertainty concerning the location of relevant information slowed decision-making speed for all subjects, but proportionately more for the older subjects (16% versus 11% for the younger age group). Uncertainty slowed responses to the changeable message sign more than to traffic signals for subjects in both age groups. The results are consistent with the spatial localization hypothesis, and suggest that older drivers may have more difficulty than younger drivers locating targets in visual search while driving. The results also suggest that effective use of changeable-message signs requires placement in locations with high expectancy, and allowing drivers sufficient time to locate the sign before reading the scrolling message.
Multivariate Model for Defining Changes in Maximal Physical Working Capacity of Men, Ages 25 to 70 Years BIBA 171-174
  Andrew S. Jackson; Earl F. Beard; Larry T. Wier; J. E. Stuteville
The purpose of this study was to develop a multivariate model with cross-sectional data that defined the decline in VO2max over time, and cross-validate the model with longitudinal data. The cross-sectional sample consisted of 1,608 healthy men who ranged in age from 25 to 70 years. VO2max was directly measured during a maximum Bruce treadmill stress test. Regression analysis showed that the cross-sectional age and VO2max relationship was linear, r = 0.45 and the age decline in VO2max was 0.48 ml/kg/min/year. Multiple regression developed the multivariate model from age, percent body fat ({percent}fat), self-report physical activity (SR-PA), and the interaction of SR-PA and {percent}fat (R = 0.793). Accounting for the variance in percent body fat and exercise habits decreased the influence of age on the decline of VO2max to just -0.27 ml/kg/min/year. This showed that much of decline in maximal physical working capacity was due to physical activity level and percent body fat, not aging. The multivariate equation was applied to the data of the longitudinal sample of 156 men who had been tested twice (Mean Age{Delta} = 3.1 ± 1.2 years). The correlation between the measured and estimated change in VO2max over time ({Delta}VO2max) was 0.75. The results of the study showed that changes in body composition and exercise habits had more of an influence on changes in maximal physical working capacity than aging. The developed model provides a useful way to quantify the changes in physical working capacity with aging.

AGING: Designing New Technologies for Older Adults

Development of a Memory Aid Design Concept for Older Users BIBA 175-179
  Mark Kirkpatrick; Randy M. Perse; Lisa A. Dutra; Michael A. Creedon; Jiska Cohen-Mansfield
This study was conducted to develop a design concept for an electronic memory device to enhance medication compliance in older users. The effort was supported by a Phase I Small Business Innovation Research (SBIR) grant from the National Institute on Aging (NIA).
   A user-oriented approach was used to develop a design concept for a memory device for older users. One hundred seniors were interviewed to identify their physical, physiological and cognitive capabilities and limitations, as well as their preferences for memory aid functions. Specific design requirements were gathered from user testing of six currently available memory aids with 30 of the original 100 elderly subjects. The interview and user testing results were consolidated to provide the basis for tradeoff criteria for memory and interface concepts, and for the development specifications for an optimal interface design for a memory aid designed specifically for the elderly user.
   A design concept was developed for a medication device that would be easy to use, would reduce the likelihood of scheduling errors, and would be non-threatening to older users who might otherwise be intimidated by an electronic device. The Phase I effort focused on enhancing medication compliance, which is a priority issue with the senior population.
Thermostats for Individuals with Movement Disabilities: Design Options and Manipulation Strategies BIBA 180-184
  Stephen Metz; Brian Isle; Sandra Denno; James Odom
Using common household products is often difficult for people with neuromuscular disorders, spinal cord injury, or arthritis. We need to better understand their capabilities when designing and adapting products that are easier for them to use. In this study, individuals with movement impairments used two experimental home control thermostats with features that allowed easier positioning and viewing. The participants employed a variety of grasping and manipulation strategies, including some that were not anticipated by the designers. Participants' preferences indicated that the appearance of the product, not just effective control design, was an important factor in their judgments. We discuss the implications of the study results for universal design and adaptation of traditional products for the elderly and those with disabilities.
Computer Anxiety and the Older Adult: Relationships with Computer Experience, Gender, Education and Age BIBA 185-189
  Jennifer L. Dyck; Janan Al-Awar Smither
Research in the area of computer anxiety has traditionally concentrated on the younger adult. In this study older adults (55 years and over) were compared to younger adults (30 years and under) on levels of computer anxiety and computer experience. Subjects in the study completed a demographic and computer experience questionnaire, and two computer anxiety scales. Previous research findings indicating a negative relationship between computer anxiety and computer experience was replicated for both young and older adults. Additional findings indicated that older adults were less computer anxious and had less computer experience than younger adults. Furthermore, older subjects indicated more liking for computers than younger subjects. However, while young males liked computers more than young females, no differences between older males and older females were found on the computer liking subscale. Some discrepancies between the two computer anxiety scales suggest further research is needed to validate computer anxiety scales for use with older adults.
The Processing of Synthetic Speech by Older and Younger Adults BIBA 190-192
  Janan Al-Awar Smither
This experiment investigated the demands synthetic speech places on short term memory by comparing performance of old and young adults on an ordinary short term memory task. Items presented were generated by a human speaker or by a text-to-speech computer synthesizer. Results were consistent with the idea that the comprehension of synthetic speech imposes increased resource demands on the short term memory system. Older subjects performed significantly more poorly than younger subjects, and both groups performed more poorly with synthetic than with human speech. Findings suggest that short term memory demands imposed by the processing of synthetic speech should be investigated further, particularly regarding the implementation of voice response systems in devices for the elderly.

COMMUNICATION: Proven Benefits and Promises

Tools for Communicating with Chemical Information: A Cognitive Engineering Analysis BIBA 193-197
  Wayne Zachary; James Hicinbothom
A major challenge for human factors is designing specialized systems to mesh with the domain expertise and mental representations of the system users. Systems for computational chemistry are an important example. Chemists use chemical structure diagrams (CSDs) as part of their basic language of communication, along with chemical formulae, narrative text, graphs and charts. Current computer tools for communicating with CSDs in written contexts are often found by chemists to be incomplete, difficult to use, and offering inappropriate functionality. This problem arises from ineffective human computer-interfaces that, in turn, can be traced to a lack of understanding on how skilled chemists use, think about, and communicate with CSDs. A formal cognitive human factors analysis is applied to address this deficiency. The analysis is developed through critical incident interviews, question-answering protocols, and thinking aloud protocols. Its results include a GOMS-type cognitive model of the drawing/manipulation process and of the conceptual structures underlying that process. Existing CSD drawing tool interfaces can be seen to provide little support for the conceptual structures or cognitive processes identified. The model developed in this research is being used to develop a user-oriented HCI for chemical structure manipulation systems.
Methodology for Software Documentation Reuse BIBA 198-201
  Marion M. Sherry
This paper describes a documentation writing methodology developed and used by the author to address some of the issues of consistency in documentation and product function, redundancy of research and solution, and product usability (including timeliness of delivery and quality of support) for a software product engineered, developed and deployed in a multi-organizational or corporate environment. The methodology is compatible with technical systems engineering, development and testing documentation requirements, and is applicable to software products for which there are existing or anticipated "user guides". The method used to accomplish these goals is the incorporation of existing user guide formats, wherever possible, in the documentation of technical specifications for detailed engineering, development and testing requirements. This paper describes the "cycle of documentation" methodology employed, identifies opportunities to use this methodology, and describes some of the benefits derived from using the methodology (both initially intended and later discovered).
Telephone Service Center Call Duration Improvement BIBA 202-206
  Robert E. Warren
Call handling duration in a telephone service center was substantially improved by providing users easier access to mainframe data systems. Switching from a system that allowed access to only one system at a time to one that provided a separate window for each system produced an estimated 7% improvement in call handling duration. The improvement was most marked for those calls which required multiple system access.
Virtual Reality and Human Factors BIBA 207-210
  John C. Thomas; Rory Stuart
The terms "Virtual Reality", "Artificial Reality", and "Cyberspace" have been prevalent in the popular press recently. There has also been considerable professional interest. (See Table 1 of recent conferences). This field is an outgrowth of three factors: 1) increases in available technologies of display, storage, and CPU along with new interface devices. 2) increases in the awareness of the importance of the "user interface" and 3) an increase in the awareness of the need for better means of collaboration.
   While "Virtual Reality" is arguably not completely new, it is only in the last few years that these technological and social trends mentioned above have resulted in the growth of "Virtual Reality" as a field.
   We argue that "Virtual Reality" is an important phenomenon for the human factors community in at least three distinct ways. First, like other new technologies, Virtual Reality requires human factors research to reach its full potential. Second, Virtual Reality offers the human factors professional an important new tool of investigation. Third, as a tool of communication and collaboration, virtual reality may serve as a medium for collaborative design and/or a means for communicating the results of human factors issues.

COMMUNICATION: Improved User Control of Phone Services

Skip and Scan Telephone Menus: User Performance as a Function of Experience BIBA 211-215
  Robert A. Virzi; Paul Resnick; Don Ottens
We present the results of a laboratory study comparing three styles of audio menus. One of these styles is the technique predominantly employed in interactive voice response (IVR) systems today. Two alternatives to this Standard technique were evaluated in this study. One of these alternatives was first proposed in Resnick and Virzi (1992), which they called Skip and Scan menus. This new style was hypothesized to be superior to Standard menus for intermediate users, but was expected to show limitations for one-time callers and expert users. The third menu alternative we evaluated combines elements of the Standard and Skip and Scan menus and was hypothesized to be superior in a broad range of usage conditions. Performance was measured over 36 tasks and two IVR applications. In all but the first few trials, the Skip and Scan menu style reported in Resnick and Virzi led to performance equal to or better than the other two menu styles. Standard menus showed a performance benefit for the first few trials of the first application only: this benefit was not present in the second application. There were no differences among the techniques in the trials simulating expert behavior.
A Usability and Diary Study Assessing the Effectiveness of Call Acceptance Lists BIBA 216-220
  John P. Chin; Richard D. Herring; M. Elliott Familant
Nuisance or unwanted calls have always been a problem to subscribers of phone services. One possible solution is a network based service that allows subscribers to control the calls they receive by using a call acceptance list. When the call acceptance list is activated, all callers not on the list would be automatically routed to a voice messaging system. Those callers on the list would be allowed to ring the subscriber's telephone. This study assessed the effectiveness of call acceptance lists in reducing unwanted telephone calls. Participants used a prototype telephone-based interface to establish a list of telephone numbers from which they would always accept calls. At the same time, they logged each of their incoming calls in a diary, recording the telephone number that originated the call, and whether they wished to receive the call. The call acceptance list significantly reduced the number of unwanted calls from 12% to 1%. However, this list also substantially reduced the number of wanted calls answered by the subscriber from 88% to 33%. Although a call acceptance list appears to be effective in blocking unwanted calls from reaching the subscriber, the list would also route a substantial number of wanted calls to voice messaging. If the majority of the calls are wanted, the results of this experiment suggest that a call rejection list would be a more effective method for preventing unwanted calls. Fewer wanted calls would be rejected while preventing unwanted calls from ringing through.
Screen-Assisted Telephony and Voice Service Usability BIBA 221
  R. D. Herring; J. A. List; E. A. Youngs
Many voice phone services are complicated to use, and several human factors obstacles may explain their lower than expected penetration and usage rates among subscribers. Usability difficulties with conventional telephones include: deciding which services are appropriate, knowing which services are available for a particular call, remembering complicated commands, and executing commands via conventional phones (e.g., network-based speed dialing).
   Bellcore sought to determine whether network services could be more efficient or acceptable to users if engineered to interface with more intelligent Customer Premises Equipment (CPE). For these reasons, it compared service usability of conventional CPE with an experimental screen-assisted telephone designed to help overcome these human factors obstacles. The experimental telephone provided a "context-sensitive" visual display showing available services, context-sensitive "soft keys" that accessed these services with a single key press, and a visual display of telephone numbers on list services.
   Usability tests showed that the experimental screen-assisted telephone provided significant gains for two services with respect to conventional CPE. The gain for Three-Way Calling (90% vs. 40% success) appeared due to automating the switch hook flashes that the service requires. The gain for Speed Calling (69% vs. 25% success) appeared due to eliminating the need to assign and remember dialing codes, and to providing feedback when an entry was incorrect. The experimental telephone also provided an average gain over all services tested (75% vs. 61% success), but this did not reach statistical significance. The results are an encouraging early attempt at creating richer visual displays for more usable network services.
Human Factors Problems in Interactive Voice Response (IVR) Applications: Do We Need a Guideline/Standard? BIBA 222-226
  Daryle Jean Gardner-Bonneau
The purpose of this paper is to present a case for the development of a user interface design guideline or standard for interactive voice response applications, to be widely disseminated throughout business and industry. A number of sample problems are cited, based on the author's consulting experience in this area, which serve to demonstrate that many of the problems encountered in IVR application development, particularly in scripting/dialogue design and use of automated speech recognition as a front-end, are not only solvable, but easily avoidable, given the current human factors knowledge base. The paper also discusses the Specification Document developed by the Voice Messaging User Interface Forum (1990, April), and the reasons why it cannot be applied, as written, to the user interface design of more complex IVR applications. Finally, the author proposes an approach to developing the proposed guideline/standard.

COMMUNICATION: Improving Mediated Communication: Acoustic, Linguistic, and Visual Factors

Catch a Rising Tone: Selecting a Tone for a New Calling Service BIBA 227-231
  Marc E. Fusco; Robert B. Katz
The tone used in the new service Caller ID on Call Waiting (CIDCW) must be reliably detected by customer premises equipment (CPE), so that it can prepare to receive caller ID data, and it should alert customers to new calls but without being annoying. To help select a tone, the first experiment of this study examined the acceptability of a series of high-frequency dual tones that might be able to perform the required CPE signaling. Subjects were presented with the tones under circumstances in which they would typically be heard (while talking and listening over the telephone) and rated the sound quality of the tones. Long bursts of tones were presented as well as short bursts prepended or appended to the 440-Hz tone used in Call Waiting service. The results suggested that customers may find high-frequency dual tones acceptable. To determine acceptable parameters of tones, in the second experiment, subjects rated the loudness of selected tones as their length and power were varied.
Control of Prosodic Features for Keyword Emphasis in a Text-to-Speech Synthesizer BIBA 232-236
  Hiroshi Hamada; Jin'ichi Chiba
For the purpose of designing a method to control the main speech parameters for keyword emphasis in a text-to-speech synthesizer, the relation between speech parameters and emphasis level is determined from experiments. Twelve subjects are instructed to modify keyword emphasis to achieve natural sounding speech from three sentences. An interactive speech editor with a graphical user interface is developed for the experiments. The editor allows the subjects to control speech intensity, speech rate and average fundamental frequency of the keyword, and of the other sentence components. Furthermore, subjects can also control pause (silence) duration preceding and following the keyword. Extracted relations between prosodic feature parameters and emphasis level shows that speech intensity and speech rate are independent of sentence content. Speech intensity increases linearly and speech rate decreases linearly with emphasis level. On the other hand, average fundamental frequency and pause duration depend on sentence content, and relatively large changes are required to strongly emphasize keywords using pause insertion and increased fundamental frequency.
Measuring Human Performance as a Function of Speech Communication Using the Close Combat Test Bed (CCTB) Facility BIBA 237-241
  Leslie A. Whitaker; Leslie J. Peters; Jennifer Mitchell
Auditory communication is critical for the successful completion of many tasks which require information be transmitted among crew members. The purpose of the present program of research is to determine the impact that speech communication has on performance of such tasks. As guidance for this program, a model of auditory communication has been developed. This model describes performance as a function of three factors: transmission, linguistic, and individual. The model assumes that variables affecting these three factors alter the level of auditory workload and task performance is a consequence of this workload (Peters, 1991). The present paper describes the effects of two transmission factors: speech intelligibility and communication structure. Speech intelligibility was measured using the Modified Rhymes Test. Communication structure was defined as command, interrogative, and discussion levels. Three studies have been completed in this research program. The focus of the present paper is the most recent study, completed at the Ft. Knox Close Combat Test Bed, an M1A1 tank simulator facility. After describing the results of this study, the results of all three studies are reviewed and found to be consistent with the auditory-performance model proposed by the authors.
Out of Site, Still in Mind? A Case Study in Video Mediated Communication BIBA 242-246
  Beverly L. Harrison; Mark H. Chignell; Ronald M. Baecker
Video mediated communication alters our perception of the way in which we interact and communicate. In contrast to face to face or audio only (e.g., telephone) communication, there is relatively little systematic research on the effect of video conferencing on communication within groups of people at dispersed locations (Harrison, 1991b; Harrison et al, 1992b; Sellen, 1992; Wolf, 1988; Cohen, 1982; Short, Williams, and Christie, 1976). In this paper we describe a study of how participants at three distant locations perceived differences between face to face (within site) and video mediated (between site) communication. Results indicate that participants perceived between site, mediated communication to be unnatural and uncomfortable. They felt there were problems with gaining floor control and with conversation flow. Additionally, participants perceived the between site, mediated communication to be less interactive, less social, and less enjoyable than the face to face, within site communication. The insights gained through this and other case studies, summarized here, will be used to guide our future research. This study is one in a series of field trials and controlled experiments aimed at understanding the human factors issues associated with video communication and the design of such systems.

COMMUNICATION: Auditory Perception

Auditory Perception BIBA 247
  Ellen C. Haas
Auditory perception involves the human listener's awareness or apprehension of auditory stimuli in the environment. Auditory stimuli, which include speech communications as well as non-speech signals, occur in the presence and absence of environmental noise. Non-speech auditory signals range from simple pure tones to complex signals found in three-dimensional auditory displays.
   Special hearing protection device (HPD) designs, as well as additions to conventional protectors, have been developed to improve speech communication and auditory perception capabilities of those exposed to noise. The thoughtful design of auditory stimuli and the proper design, selection, and use of HPDs within the environment can improve human performance and reduce accidents.
   The purpose of this symposium will be to discuss issues in auditory perception and to describe methods to improve the perception of auditory stimuli in environments with and without noise. The issues of interest include the perception of non-speech auditory signals and the improvement of auditory perception capabilities of persons exposed to noise.
A Pilot Study on the Perceived Urgency of Multitone and Frequency-Modulated Warning Signals BIBA 248-252
  E. C. Haas
In some environments, there is a serious mismatch between the perceived (psychoacoustic) urgency of a warning and its situational urgency. This pilot study investigated effect of pulse format, pulse duration, and time between pulses on the perceived urgency of warning signals. The intent was to determine the best combination of variables and levels of variables to use in a formal study on the perceived urgency of warning signals. The results indicated that only pulse format and time between pulses were significant. Subjects rated sequential pulses as being less urgent than any other format. Signals with shorter inter-pulse intervals were rated as significantly more urgent. Pulse format and time between pulses were determined to be variables which should be used in future research.
Masking between Spatially Separated Sounds BIBA 253-257
  Michael D. Good; Robert H. Gilkey
The development of optimal three-dimensional auditory displays requires a more complete understanding of the interactions among spatially separated sounds. Free-field masking was investigated as a function of the spatial separation between signal and masker sounds within the horizontal, frontal, and median planes. The detectability of filtered pulse trains in the presence of noise maskers was measured using a cued, two-alternative, forced-choice, adaptive staircase procedure. Signal and masker combinations in low (below 2.3 kHz), middle (1.0-8.5 kHz), and high (above 3.5 kHz) frequency regions were examined. As the sound sources were separated within the horizontal plane, signal detectability increased dramatically. Similar improvement in detectability was observed within the frontal plane. As suggested by traditional binaural models, interaural time cues and interaural intensity cues are likely to play a major role in mediating masking release in both the horizontal and frontal planes. Because no interaural cues exist for stimuli presented within the median plane, traditional models would not predict a release from masking when the stimuli are separated within this plane. However, with high frequency signals, masking release similar to that observed in the horizontal and frontal planes could be observed in the median plane. The current literature suggests that sound localization in the median plane may depend on direction-specific spectral cues that are introduced by the pinna at high frequencies. The masking release observed here may also depend on these "pinna cues."
Technology Advancements in Hearing Protection: Active Noise Reduction, Frequency/Amplitude-Sensitivity, and Uniform Attenuation BIBA 258-262
  John Gordon Casali
Conventional hearing protection devices have often been implicated in compromised auditory perception, degraded signal detection, and reduced speech communication abilities. Recent technological developments have been used to augment hearing protectors in an attempt to alleviate these problems for the user, while at the same time providing adequate attenuation. Operational characteristics, design features, performance data, and applications for active noise reduction, sound transmission, frequency-selective, adjustable attenuation, amplitude-sensitive, and uniform attenuation devices are discussed.
Systematic Errors Occur in the Discrimination of Complex Audio Signals BIBA 263-267
  Jeffrey M. Gerth
Previous research suggests that the temporal pattern of dissimilar sounds may be a basis for confusion. To extend this research, the present study used complex sounds formed by simultaneously playing components drawn from four sound categories. Four temporal patterns, determined by sound duration and duty cycle were also used, producing a total of 16 basic components. The density (i.e., number of components played simultaneously) ranged from one to four. Subjects heard a sequence of two complex sounds and judged whether they were same of different. For trials in which the sounds differed, there were three possible manipulations: the addition of a component, the deletion of a component, and the substitution of one component for another.
   Overall accuracy was 94 percent across the 144 dissimilar sound complexes. As density increased, a significantly greater number of errors occurred for all classes of manipulations. Changes in individual temporal patterns across a variety of manipulations of sounds involving adding, deleting and substituting components were accurately discriminated. Subjects were least accurate in detecting substitutions of a pattern. A single sound category was identified in error prone sequences which was most often involved as the changing component from first to second sound presentation. Suggestions for the design of easily discriminated sounds are discussed.

COMPUTER SYSTEMS: Keyboard Input Devices

Infogrip Chordic Keyboard Evaluation BIBA 268-271
  H. Lu; F. Aghazadeh
This paper presents a preliminary evaluation of a computer data entry device called Infogrip Chordic Keyboard. Learning time, typing speed and accuracy, and operator discomfort are examined. The result shows that the 30 chords can be learned in two hours. The subjects could type 49 characters per minute with the accuracy of 98.3 percent after two hours training.
Use and Research Issues of a New Computer Keyboard BIBA 272-275
  K. H. E. Kroemer
For use with computers, the traditional QWERTY keyboard has been enlarged to more than 100 keys. This has generated postural and motoric challenges for the user, including cumulative trauma disorders. Among the proposed ergonomic solutions is the Ternary Chord Keyboard (TCK) which has only eight keys. Its evaluation posed use and research issues. TCK operation requires fast and finely controlled force and displacement by the fingertips in a horizontal plane, i.e., "rocking" of keys instead of their familiar "tapping". Associated mental tasks include memorization of the chords for each character.
   Experiments were performed (a) on TCK prototypes to measure the time needed to memorize and learn its operation, and to assess keying performance; and (b) on specially designed experimental apparatus to measure finger mobility, strength, and speed. The results indicate that finger mobility, strength and tapping performance were not well correlated with keying performance. All subjects were able to learn to operate the TCK, requiring memorization of 58 chords, within two to ten hours. After additional about 10 hours of use, they were inputting averages of 70 characters per minute, or more, with an accuracy of better than 97 percent.
   These results indicate that key operation such as with the TCK, which is rather different from the traditional QWERTY keyboard use, is feasible.
Description and Prediction of Long-Term Learning of a Keyboarding Task BIBA 276-280
  Mark McMulkin
The goal of this study was to determine an equation ("learning function") that describes long-term learning of a new keyboard. Five subjects learned 18 characters on a chord keyboard, then improved keying speed by inputting typical numeric keypad text for about 60 total hours. Their performance, in characters typed per minute, was recorded for every trial. Of the various functions that were considered to describe performance, the best fitting equation was a Log-Log relationship of the form CPMi = eb{sub:0}Tib{sub:1}, where CPMi is the performance in characters per minute on the i-th trial (Ti) and b0 and b1 are fitted coefficients.
   A second goal was to investigate how many trials of performance are needed before the entire learning function can be determined. The coefficients of the Log-Log function were determined using only the first 25, 50, 75, 100, 125, 150, 175, and 200 of the initial performance points (out of about 550 total actual data points). The mean squared error (MSE) was calculated for each of these fits and compared to the MSE of the fit using all points. From the results of MSE data, it appears that at least 50 performance data points are required to reduce the prediction error to an acceptable level.
Key Force and Typing Performance BIBA 281-282
  David F. Loricchio
The IBM Design Center in Boca Raton studied the operating-point key force for a portable computer keyboard. Alden, Daniels, and Kanarick (1972) report that typists prefer operating-point key forces of between 25 and 150 grams. We compared different key forces that fell within the range recommended by Alden et al. The only difference between the keyboards we studied was the amount of force required to activate the keys. The first keyboard (58 keyboard) required 58 grams of force to activate the keys. The second keyboard (74 keyboard) required 74 grams of force to activate the keys. Sixteen skilled typists used both keyboards to enter text. Input speed was significantly faster on the 58-gram keyboard. A significant number of typists preferred the 58-gram keyboard. The results suggest that the optimal key force for portable computer keyboards is less than 74 grams.

COMPUTER SYSTEMS: Handwriting, Speech, Touchscreen, and Other Input Techniques

On Handwriting Recognition System Performance: Some Experimental Results BIBA 283-287
  Paulo J. Santos; Amy J. Baltzer; Albert N. Badre; Richard L. Henneman; Michael S. Miller
Performance of a rule-based handwriting recognition system is considered. Performance limits of such systems are defined by the robustness of the character templates and the ability of the system to segment characters. Published performance figures, however, are typically based on pre-segmented characters. Six experiments are reported (using a total of 128 subjects) that tested a state-of-the-art recognition system under more realistic conditions. Variables investigated include display format (grid, lined, and blank), surface texture, feedback (location and time delay), amount of training, practice, and effects of use over an extended period. Results indicated that novice users writing on a lined display (the most preferred format) averaged 57% recognition performance. By giving subjects continuous feedback of results, training, and after about 10 minutes of use, the system averaged 90.6% character recognition. Following three hours of interrupted use and with performance incentives, subjects achieved an average 96.8% accuracy with the system. Future work should focus on improving the ability of the recognition algorithm to segment characters and on developing non-obtrusive interaction techniques to train users, to provide feedback and to correct mis-recognized characters.
Enhanced Recognition Accuracy with the Simultaneous Use of Three Automated Speech Recognition Systems BIBA 288-292
  Timothy P. Barry; Kristen K. Liggett; David T. Williamson; John M. Reising
Two studies were performed to test the efficacy of using three different automated speech recognition devices in parallel to obtain speech recognition accuracies better than those produced by each of the individual systems alone. The first experiment compared the recognition accuracy of each of the three individual systems with the accuracy obtained by combining the data from all three systems using a simple "Majority Rules" algorithm. The second experiment made the same comparison, but used a more sophisticated algorithm developed using the performance data obtained from experiment 1. Results from the first experiment revealed a modest increase in speech recognition accuracy using all three systems in concert along with the Simple Majority Rules (SMR) algorithm. Results from the second experiment showed an even greater improvement in recognition accuracy using the three systems in concert and an Enhanced Majority Rules (EMR) algorithm. The implications of using intelligent software and multiple speech recognition devices to improve speech recognition accuracy are discussed.
Touchscreen Interfaces for Alphanumeric Data Entry BIBA 293-297
  Catherine Plaisant; Andrew Sears
Touchscreens have been demonstrated as useful for many applications. Although a traditional mechanical keyboard is the device of choice when entering alphanumeric data, it may not be optimal when only limited data must be entered, or when the keyboard layout, character set, or size may be changed. A series of experiments has demonstrated the usability of touchscreen keyboards. The first study indicated that users who type 58 wpm on a traditional keyboard can type 25 wpm using a touchscreen and that the traditional monitor position is suboptimal for touchscreen use. A second study reported on typing rates for keyboards of various sizes (from 6.8 to 24.6 cm wide). Novices typed approximately 10 wpm on the smallest and 20 wpm on the largest of the keyboards. Users experienced with touchscreen keyboards typed 21 wpm on the smallest and 32 wpm on the largest. We then report on a recent study done with more representative users and more difficult tasks. Thirteen cashiers were recruited for this study and were required to complete ten trials in which they typed names and addresses with punctuation. Results indicate that the users improved rapidly from 9.5 wpm on the first trial to 13.8 wpm on the last trial, reaching their fastest performance after only 25 minutes. Although custom interfaces will be preferred for special types of data (e.g. telephone numbers, times, dates, colors) there will always be situations when limited quantities of text must be entered. In these situations a touchscreen keyboard can be used.
A Comparison of Direct-Manipulation, Selection, and Data-Entry Techniques for Reordering Fields in a Table BIBA 298-302
  Thomas S. Tullis; Marianne L. Kodimer
A useful feature of data base systems is to allow the user to change the order in which fields appear in the columns of a table. The purpose of this study was to compare the usability of seven different user interfaces for performing this task in the Microsoft Windows environment. The fields to be reordered were file name, file number, size, and creation date. The seven approaches studied covered a range of interaction styles, including dragging and dropping, menu selection, text entry, and button pressing. Fifteen Windows users completed a set of two practice trials using each approach, followed by a set of twelve main trials. For each trial, the user was shown the current order of the fields and a target order to change to. The completion times showed significant differences according to the approach used. Overall, a data-selection technique using radio buttons and a data-entry technique using a single entry area were significantly faster than all of the others. Another data-entry technique, involving multiple entry areas, was consistently the slowest. Somewhat surprisingly, given the current trend toward direct-manipulation interfaces, the two approaches involving dragging and dropping were not among the most effective approaches.

COMPUTER SYSTEMS: Cursor Control and Other Input Techniques

A Comparison of Three Pointing Devices: Mouse, Cursor Keys, and a Keyboard-Integrated Pushbutton BIBA 303-305
  David F. Loricchio
The IBM Design Center in Boca Raton studied an integrated pointing device for a personal computer keyboard. The device, a pushbutton, is a flat, round button that tilts and moves the cursor in the direction of tilt. We wanted to know if this device would be acceptable to computer users. Twelve participants used the pushbutton, a mouse, and the cursor movement keys to select targets and edit text. Participants without previous mouse experience hit significantly more targets with the pushbutton than with the mouse. Participants with previous mouse experience performed significantly better on both tasks with the mouse, and preferred the mouse over the pushbutton and the cursor keys. Several participants said that the pushbutton was too sensitive and difficult to control. The results suggest: 1. The pushbutton tested in this study would not be acceptable to users; 2. The pushbutton operation could be more accurate if the force-to-motion mapping were improved.
The Predictability of Cursor Control Device Performance Based on a Primitive Set of User Object-Oriented Cursor Actions BIBA 306-310
  Joseph D. Chase; Sherry Perdue Casali; H. Rex Hartson
The ability to predict performance with a cursor control device on a complex task by measuring performance on a simple task would be useful in evaluating alternative input devices in many types of novel situations. A user would simply have to perform simple cursor movements with each candidate device, and predictions could be made of his/her performance with the devices on any given software application. Such an approach would reduce tedious trial and error procedures, as well as eliminate the time necessary to first learn various software applications. The current study employed the User Action Notation (UAN), a task-oriented notation that describes the behavior of the user and the interface during their cooperative performance of a task, to decompose complex tasks into primitive components. A set of primitive cursor actions was developed which contains the elementary cursor actions found in complex tasks. A graphics software application was then evaluated, using the UAN, with respect to the frequency of occurrence of each of the primitive user-cursor actions. Individual's ability to perform each primitive user-cursor action with three different input devices was then be measured. These measures were used to form estimates of the individual's ability to perform the graphics task with each input device. Correlations between predicted performance and measured performance on the graphics task were found to exceed 0.9. Results demonstrate the success of the method described herein for predicting complex task performance based on simple task performance, as well as, the usefulness of the UAN for decomposing complex tasks into primitive components.
Cursor Control Device Use by Persons with Physical Disabilities: Implications for Hardware and Software Design BIBA 311-315
  Sherry Perdue Casali
Computer technology has the potential to offer individuals with physical limitations greater levels of independence and increased opportunities for meaningful employment, but this can only be realized when the individual can interact efficiently with the computer. Choosing a cursor control device is particularly important given the growing popularity of direct-manipulation style interfaces. Twenty persons with impaired hand and arm function (as a result of a spinal chord injury) and 10 nondisabled persons performed a target acquisition task with five cursor control devices: a mouse, trackball, cursor keys, joystick, and tablet. Even persons with profound impairment were able to compensate for their disability and operate each device by using minor device modifications and/or unique operating strategies. These modifications and compensation techniques are described. Regardless of the physical skill level of the user, the rank ordering of the five devices with respect to target acquisition time was the same. The mouse, trackball, and tablet provided better performance than the keys, which provided better performance than the joystick. Dragging was particularly problematic for persons with motor control limitations, as was acquiring small targets. The implications of the results for hardware and software design are discussed.
COAS: Combined Object-Action Selection: A Human Factors Experiment BIBA 316-320
  J. F. Kelley; J. Ukelson
12 participants with a high level of domain experience used two different, mouse-based, interaction techniques to carry out three workstation file management tasks of varying complexity. One technique followed a standard Object-Action model; the other was a newly developed technique called COAS (Combined Object-Action Selection). There was little difference in performance on a simple task; performance for participants using the new technique was 38% faster on a moderately complex task and was 21% faster on a complex task. The file management application, interaction techniques and experiment were implemented in an OS/2 Presentation Manager style using ITS (Interactive Transaction System).

COMPUTER SYSTEMS: Color, Menus, and Other Information Presentation Techniques

The Impact of Color Coding in Program Debugging BIBA 321-325
  T. Kiki Widjaja
The potential of using color as a program debugging aid was investigated in this research. The study assessed program debugging performance of eighteen subjects in three different color coding conditions: black and white, color-grouping that arranged loops and nested structures in five shades of green, and color-flagging that highlighted potential error areas in orange. Completion time, accuracy, and types of error detected, subjective preferences, and rate of visual comfort for each condition was recorded. This research suggested that color coding substantially improved error detections in C programs.
Increasing or Decreasing? The Menu Direction Effect on User Performance BIBA 326-330
  Ram R. Bishu; Ping Zhan
Although the breadth/depth issue in menu design has been identified to have significant effects on user performance, the effects of menu direction and dimension have not been well investigated, especially as iconic menus as concerned. This study investigated the effects of menu direction and dimension on user selection performance by using two different dimensions (sizes) of iconic menu systems (16-item and 32-item). The direction of the menus consisted of "increasing" and "decreasing", with the depth of menu ranging from 2 to 3 levels. The findings indicated that "decreasing" direction menus were significantly quicker and more accurate than "increasing" menus. However, for the smaller size menus (16 item menus), user performance accuracy was better with the "increasing" direction menus. Overall, the results showed that "decreasing" direction menus are superior to "increasing" menus. It is suggested that for small size iconic menus (e.g., up to 32 items), items should be organized in "decreasing" direction, especially when speed is of particular importance to the selection task.
Organizing the Domain of Menus BIBA 331-335
  Stephen C. Gibbons
This paper will present a global definition for menu systems and propose a domain structure in support of this definition. A literature review was conducted to provide broad, integrated coverage and critical assessment of past and present research trends. This effort provides the background necessary to present our definition of menu dialogues by outlining the present state of domain knowledge. The proffered definition divides the domain into three areas: allowable menu system structures, identifiable menu system objects; and menu system sequence control aspects. These three areas are expanded in the paper to support the definition and function as an organizational framework for the domain.

COMPUTER SYSTEMS: Computer-Based Displays I

An Application of the Semantic Differential to Icon Design BIBA 336-340
  Rungtai Lin
Previous studies have indicated that the semantic differential was effective in evaluating comprehension of icons. However, the capability of semantic differential ratings depends on whether the underlying rating factors have been chosen properly. It is necessary to find out what cognitive factors affect the evaluation of an icon. Then, these factors can be used as the basis for semantic differential ratings on the proposed icons during the design stage. Most of the studies are focused on the evaluation after the design is completed. Very few have ever mentioned the approaches of icon evaluation at the design stage to ensure the design quality. Therefore, the purpose of this study is intended to derive and validate the cognitive factors that affect icon designs, and to provide designers with a tool having predictive information for evaluating and modifying the proposed icons at an early design stage.
Understanding the Image Functions for Icon Design BIBA 341-345
  Rungtai Lin; John G. Kreifeldt
Because icons vary from very representational to extremely abstract symbols in a user interface, an important issue faced by designers when designing an icon is how to select an appropriate design style for the image. There are no simple rules that can be followed by designers to determine the design style. The present study is intended to help designers to choose a proper design style for the icon at an early design stage. First, a classification of icons is summarized and the levels of stylization are discussed and demonstrated with examples. Then, thirty icons from several drawing packages and generally used symbols are selected, and a matching test is conducted to obtain the correct matching rates. The results are presented with some explanations for icon recognition and confusion, and finally how to select the right image function for icon design is discussed.
Assessment of a Head-Mounted Miniature Monitor BIBA 346-350
  Joseph P., II Hale
Two experiments were conducted to assess the capabilities and limitations of the Private Eye, a miniature, head-mounted monitor. The first experiment compared the Private Eye with a cathode ray tube (CRT) and hard copy in both a constrained and unconstrained work envelope. The task was a simulated maintenance and assembly task that required frequent reference to the displayed information. A main effect of presentation media indicated faster placement times using the CRT as compared with hard copy. There were no significant differences between the Private Eye and either the CRT or hard copy for identification, placement, or total task times. The goal of the second experiment was to determine the effects of various local visual parameters on the ability of the user to accurately perceive the information on the Private Eye. The task was an interactive video game. No significant performance differences were found under either bright or dark ambient illumination environments nor with either visually simple or complex task backgrounds. Glare reflected off the bezel surrounding the monitor did degrade performance. It was concluded that this head-mounted, miniature monitor seems well suited for in situ operations that require ready reference to information and could serve a particularly useful role in microgravity environments.
Multiple Monitors vs. Windowing Presentation Styles for Shop-Floor Controls BIBA 351-355
  Shang H. Hsu; Chou Shen
Windowing systems seem to provide promising alternatives to display massive information for multi-tasking and real-time control systems. However, the benefits of windowing systems might be offset by the workload resulting from window management. The purpose of this study was to compare the relative advantages of tiled window, overlapping window, and twin monitors for high-demand and low-demand information-processing shop-floor control tasks. It was found that tiled windowing system was superior to the other two for high-demand tasks while twin monitors was the best for low-demand tasks.

COMPUTER SYSTEMS: Computer-Based Displays II

Making Queries Look Like Links: An Interaction Style for Information Exploration BIB --
  Gene Golovchinsky; Mark H. Chignell
An Evaluation of Computer-Supported Backtracking in a Hierarchical Database BIBA 356-360
  Cortney G. Vargo; Clifford E. Brown; Sarah J. Swierenga
This study was designed to investigate whether computer-supported backtracking tools reduced navigation time over manual backtracking and to compare navigation times among a subset of four backtracking tools. Each tool was evaluated in the context of an experimental, hierarchical, direct-manipulation database. Trials consisted of an information retrieval task requiring subjects to answer multiple-choice questions about the contents of the database. The independent variables included the backtracking tool and the backtrack navigation Task Length. The dependent measures included navigation time, the frequency with which the computer tool was selected and used over manual backtracking (a Table of Contents), and questionnaire responses. Backtracking with any of the four computer-supported tools resulted in a significantly reduced navigation time over manual backtracking using the Table of Contents. When provided with a history list, subjects had significantly smaller navigation times when backtracking at the higher of two levels in the database hierarchy. There were no differences between computer tools in rated efficiency, ease of use, or objective or subjective preference measures.
A User Interface Design Concept for Visualization of Multidimensional Process Models BIBA 361-364
  Peter T. Bullemer; Stephen V. Metz; Rose Mae Richardson
We describe a user interface design concept for the interactive visualization of multidimensional industrial process models. Key features of the design include: a matrix layout of 3-D and 2-D graphical plots, an interaction area for visualizing integral relationships and selecting context for viewing individual x-y functions, and a reference area extending throughout the matrix for maintaining focus on desirable values of product quality. These features are motivated by task-specific needs to develop conceptual models of the physical processes used in making products. Conceptual models enable process engineers to determine the optimal operating ranges for controllable process parameters.
A Componential Model of Human Interaction with Graphs. II. Effects of the Distances among Graphical Elements BIBA 365-368
  Douglas J. Gillan; Michael Neary
Based on task analyses of people using graphs, Gillan and Lewis (1992) have developed a model that describes how people interact with graphs. The model proposes that for simple tasks (e.g., comparisons and subtraction) and common graphs (e.g., line, scatter, and bar graphs), graph users apply combinations of five component processes -- Searching for indicators, Encoding the value of indicators, performing Arithmetic Operations on the values, making Spatial Comparisons among the indicators, and Responding. The model further suggests that the combination and order of the components that the user applies depends on a user's task and the type of graph. The present research investigated two predictions from the model concerning spatial relations in a graph: (1) that response times to answer comparison questions should be sensitive to varying the distance between two indicators, but not to varying the indicator-to-axis distance, and (2) that response times to answer difference questions should be sensitive to the distance between the indicator and the y-axis, but not to the distance between the indicators. In the experiment, subjects used line and bar graphs to answer comparison and difference questions in which the appropriate distances varied systematically. The results of the research supported both predictions, thereby providing empirical validation of the model. In addition, some aspects of the model were not anticipated by the model, suggesting the need to enhance the componential model.

COMPUTER SYSTEMS: Tools and Techniques

Machine-Recorded Protocols: Tools and Techniques BIBA 369-373
  John B. Smith; Dana Kay Smith; Eileen Kupstas
The UNC Textlab/Collaboratory Project has developed a set of tools and techniques for recording and analyzing machine-recorded protocols of users while they work with an application system developed by our project -- in the case described here, a hypertext-based writing environment, called WE. A tracking facility automatically records users' actions. Replay allows a researcher to recreate and view a user session in time proportional to the original, in uniform time, and in manually controlled steps. Our grammar incorporates a cognitive model of the users' mental behaviors for the task of expository writing and parses protocols to produce parse trees that show users' strategies for working sessions. Finally, our display tools work with these data to produce static and animated representations from which researches can infer user strategies and patterns of behavior. In this paper, we discuss the tools we have developed and issues they raise. While this methodology is described with respect to a particular task and system, it is quite general and could be used for other systems and purposes. A brief conclusion outlines our current and future work, including our plans for a comprehensive protocol analysis environment that can be used by other researchers as well as our group and our plans to extend our tools and method to record, analyze, and display multiple protocol streams for groups of individuals working collaboratively.
Evaluating User Interface Development Tools BIBA 374-378
  Deborah Hix; Tim Ryan
This paper describes a procedure for quantitatively evaluating and comparing user interface development tools, and presents results of evaluating for user interface development tools with the procedure. For each tool, summary numeric ratings for functionality and usability are presented. General conclusions about the four tools and about the tool evaluation procedure itself are also discussed.
Taking the "Task" Out of Task Analysis BIBA 379-383
  Janet L. Fath; Randolph G. Bias
Task analysis is a well-accepted component of user-centered design. It is often left out of the design process, however, due to a lack of practical methods, the difficulty in predicting the amount of resource required to perform it, and a short supply of people with the appropriate skills. A solution to these problems is a structured set of activities that compose a task analysis and relate to the overall design process.
   The general framework into which these activities fit has three phases: Data Collection, Data Analysis, and Design. During the Data Collection phase, user and task data are collected and validated. The Data Analysis phase requires analyzing the user and task data in a way that results in suggestions for information representation, navigation, terminology, and consistency. Finally, the Design phase requires translating the suggestions from the Data Analysis phase into a viable product.
   A prototype task analysis workbook was developed to assess the feasibility of the structured approach to task analysis. The workbook includes tools for data collection, data analysis, and design, as well as instructions for how to use the tools. Over a period of two years, the workbook was used in five different development projects. A representative from each group was interviewed to determine how the workbook was used and which parts were most useful. Results of the interviews indicate that the workbook approach has merit.
An Incremental Approach to User Systems Interface Design: Replacing the Prototype in X Windows Systems BIB --
  Jeffrey W. Mahony; Mark W. Smith


Maintaining Stasis: Why User Acceptance of Advanced Technology is So Hard to Get (And What to Do about It) BIBA 384-388
  Frank L. Greitzer; Nancy J. Spalding
The focus of this paper is on user-centered systems engineering activities supporting the acquisition, requirements gathering, and preliminary design of a major technology advancement for an operating commercial command and control system. Major activities included establishment of user-centered customer and developer organizations, knowledge acquisition, human-machine interface design and prototyping, scenario and system simulation development, and demonstration of the proposed system. Because the system was designed with substantial user input, it received a high degree of user acceptance.
User-Centered Design in Manufacturing Applications: The Development of a Capacity Planning Tool BIB --
  Sally M. Cohen
Architects at Work: The Structure of Design Information BIB 389-393
  Andrew M. Cohill
Designing and Implementing Decision Aids for a Complex Environment Using Goal Hierarchies BIBA 394-398
  Monica Zubritzky Weiland; Boyd Cooke; Brad Peterson
In dynamic tactical environments such as Anti-Submarine Warfare (ASW), operators must continuously balance goals for safety with mission goals and objectives as the tactical situation evolves. These high-level goals introduce specific constraints on operator actions that often conflict with one another. Being able to assess and balance conflicting constraints is thus a key element of the operator's cognitive processes. This design effort extends the COGNET (COGnition as a NEtwork of Tasks) modelling methodology in order to identify and resolve goal/constraint conflicts as they arise in the tactical context. COGNET is a meta-model, or architecture, for building and embedding models of human operators in real-time, multi-tasking systems. It integrates the GOMS notation for building operator task models with the blackboard architecture for building a knowledge representation, and production rules that link the tactical situation with the changing knowledge representation. An extension to the model was added in the form of AND/OR tree diagrams that represent the relationship between high level goals and lower level constraints on operator actions. The goal/constraint trees were modelled for the Submarine Operational Automation System (SOAS) operator using expert knowledge elicitation techniques. Results of the modelling effort indicate that operators must often keep track of many conflicting constraints in making decisions on ship course, speed, and depth, and often do not consider the complete set of constraints because of the limits on working memory. This finding highlights the need for decision aids for managing goals and goal conflicts. Applications of the goal/constraint hierarchies with a COGNET model framework to the design and implementation of SOAS decision aids are discussed.

COMPUTER SYSTEMS: Usability and Rapid Prototyping

Does the Fidelity of Software Prototypes Affect the Perception of Usability? BIBA 399-403
  Michael E. Wiklund; Christopher Thurrott; Joseph S. Dumas
The objective of this study was to investigate whether the aesthetic refinement of a software prototype is related to subjects' ratings of the usability of the prototype. We purchased a commercially available electronic device offering the functions of dictionary, calculator, and thesaurus (hereafter referred to as the Dictionary). We created four user interface prototypes of the Dictionary using line art, half-tone, gray scale, and color images of the product. The prototypes varied in the degree to which the displayed image resembled the physical look of the real product in terms of depth, tone, color, etc. All of the prototypes were interactive in that subjects could, with a mouse, make the prototypes operate like the Dictionary. Five groups of ten subjects each then made their ratings and performed tasks using either one of the prototypes or the Dictionary. The subjects rated ease of learning and use, forgiveness of mistakes, and aesthetics for the version they used, before and after performing tasks. Subjects who used a prototype also repeated a task using the real product and compared the two in terms of similarity of interaction and aesthetics. The results indicated that the aesthetic quality of prototypes within the range we varied did not bias users for or against the prototype's perceived usability. However, we learned that half-tone prototypes should be avoided when their coarse shadings decrease legibility. In addition, we found that making prototypes mimic the response time of a product or a design concept is important. When the real product produces slower response times, prototype performance may give an overly optimistic picture of the product's usability.
Managing: To Succeed with Rapid Prototyping BIBA 404-408
  Jim A. Carter
Rapid prototyping is a powerful tool both for analyzing user requirements and for involving the users in the design of suitable user interfaces. With it, the analysts/designers have users focus on frequent presentations of incomplete prototypes in order to get realistic expressions of the users' needs and wants. If not properly managed, these presentations may miss their objectives and either become high pressure sales pitches for designs or endless cycles of minor changes.
   Suitable management methods are required to ensure that the use of prototyping provides its expected benefits. The process oriented nature of prototyping requires some different management techniques from those used to manage more traditional and artifact oriented analysis and design activities.
Usability Testing vs. Heuristic Evaluation: A Head-to-Head Comparison BIBA 409-413
  Robert W. Bailey; Robert W. Allan; P. Raiello
The importance of user testing, heuristic evaluation and iterative design in the development of computer software programs was examined. In the first study, twenty-five subjects with limited computer experience, were randomly divided into five groups of five subjects each. All groups were asked to perform a telephone bill inquiry task using two character-based screens. After having one group perform, one change per screen was made before beginning the testing of the next group. The system was improved three times. A final experimental group completed the same task using an "ideal" system designed and presented by Molich and Nielsen (1990). Rather than the 29 changes originally suggested by Molich and Nielsen, our results showed that only one change to each of the original screens was necessary to achieve the same performance and preference levels as those demonstrated by their "ideal" system. The same task was repeated using a graphical user interface. A heuristic evaluation suggested up to 43 potential changes, whereas the usability test demonstrated that only two changes optimized performance. These findings demonstrate one of the major weaknesses of heuristic evaluations, and the importance of usability testing in the design and development of human interfaces.
IDEAL: A Software Tool to Evaluate Interface Usability BIBA 414-417
  Stacey Ashlund; Deborah Hix
This paper reports on the design, prototype implementation, and formative evaluation of a software tool -- IDEAL (Interface Design Environment and Analysis Lattice). IDEAL integrates usability engineering techniques and behavioral task representations with a graphical hierarchy of user tasks to support formative evaluation of an evolving user interface. Representative users of IDEAL -- interface designers and evaluators -- participated in two phases of formative evaluation of IDEAL. Empirical evaluation showed IDEAL to be useful as an automated tool for managing the interrelated tasks of user interface development, including interaction design, usability specification, creation of benchmark tasks, and formative evaluation, that are currently performed manually.

COMPUTER SYSTEMS: Design Guidelines

The Sophistry of Guidelines: Revisiting Recipes for Color Use in Human-Computer Interface Design BIBA 418-422
  David D. Woods; Leila Johannesen; Scott S. Potter
A survey study of color guidelines for user-computer interface design was undertaken and assessed against relevant knowledge about the human perceptual system. The main problem found is that some guidelines are dissociated from knowledge of how the human perceptual system works in relation to the constraints of the computer as a medium for perception. The guidelines approach, whose goal is to produce straightforward, concise recommendations for a diverse audience, may encourage this situation. Some specific problems and gaps in color guidelines are discussed. An alternative approach based on gearing guidance to the difficulties and common problems faced by designers is sketched.
Advanced Control Room Design Review Guidelines: Merging Old and New BIBA 423-427
  Richard J. Carter; Jerry A. Wachtel
The nuclear power industry is currently developing operator interface systems based on innovative applications of digital computers. To assure that this advanced technology is incorporated in a way that maximizes the potential safety benefits of the technology and minimizes the potential negative effects on human performance, human factors principles must be considered. NUREG-0700 contains guidelines for the review of operator interfaces. However, in light of the rapid technological advances in digital technology which have taken place in the eleven years since its publication, it is no longer adequate to assess the rapidly changing human-system interfaces. A research program, the purpose of which is to upgrade NUREG-0700, has been initiated. Thus far a set of draft advanced control room design review (ACRDR) guidelines has been complied. Three tasks, which were oriented towards integrating the applicable guidelines in NUREG-0700 into the ACRDR document, are described in the paper.
The Effects of Using a Hypertext Tool for Selecting Design Guidelines BIBA 428-432
  Jeffrey A. Fox
Designing a User-System Interface (USI) is a complex task that has been approached in many ways. One approach has been to use USI design guidelines to help improve the quality and consistency of USIs. To be effective, a general set of guidelines must be tailored to a specific application. This study investigated the effects of using a hypertext design aid (DRUID, Dynamic Rules for User Interface Design) for the selection of USI guidelines by both experienced and novice guideline users. Results indicate that, in general, the participants performed their tasks as well with DRUID as with the book. However, the participants accessed the material differently for each medium and they selected more guidelines that were relevant when using the paper book. Subjectively, the software was preferred because it provided assistance in the selection process and provided additional time-saving design aids not available in the book.
Usability Analysis of Design Guideline Database in Human-Computer Interface Design BIBA 433-437
  Katsuhiko Ogawa; Shun-ichi Yonemura
Human-computer interface design guidelines are useful for developing well designed interfaces but the designer must be able to access the guideline appropriate to the application. Research is conducted to understand how designers access design guideline databases and then methods are tested to improve the usability of the databases. A design guideline database of approximately 300 guidelines is developed using a hypermedia approach. The system employs a book metaphor interface to characters and graphics in a Japanese environment. The subjects of the usability analysis are software designers who did not have any background in human factors. They were provided with the representation of a bad interface design on a piece of paper, and were instructed to improve the design through the use of the guideline database. Two common strategies were identified by observing the designers' actions: a hypothesis strategy and a checklist strategy. These strategies were analyzed using the quantities and quality of improvements recommended. The optimum database usage checks interface violations by employing the browsing function of the database; sometimes key word searches are used.

COMPUTER SYSTEMS: Computer System Potpourri

The Turing Test of 1991 BIBA 438-442
  H. McIlvaine Parsons
Interactive computer programs and human participants competed in a Turing Test at the Boston Computer Museum last November in the first year of a competition to determine, ultimately, whether such programs can be indistinguishable from humans in dialogues. The test is named for the British mathematician and computer pioneer who proposed it in 1950. This paper describes the competition, its preparation, and problems which await resolution in future Turing Tests that may culminate in a $100,000 award. The 1991 test was "restricted" in its rules and procedures lest a full test disadvantage the computer programs too severely. The contest posed issues concerning dialogue domains, language processing, inclusion of cognitive tasks, and other features. Since a Turing Test could be interpreted as involving "thinking" and "intelligence" (though Turing had little use for such terms), future tests should intrigue human factors.
The Interface between Human Factors and Design BIBA 443-447
  Douglas J. Gillan; Randolph G. Bias
Software designers with limited knowledge of human factors often play a crucial role in the design of user interfaces. The thesis of this paper is that the field of human factors needs to be concerned with the design of interfaces between itself and the rest of the design community. We identify the mission objective for the human factors-design interface as improving the overall quality of design by enhancing communication and the transfer of knowledge. A selected set of requirements for the interface includes (1) communication, from human factors to designers, of proven and relevant design approaches, and (2) communication, from designers to human factors, of pertinent design constraints and methods of integrating human factors concerns and data into design. A discussion of concepts for the human factors-design interface describes and analyzes educational technologies (e.g., video classes and short courses), an electronic gatekeeper (a bulletin board-like system through which human factors experts and designers communicate), and design analysis software (which automatically apply human factors principles to designs).
Standards, the Future, and Designers BIBA 448-452
  Jim A. Carter
This paper explores the growing relationship between HCI developers and HCI standards. It includes a comprehensive background of WHO (more than just users and developers), WHAT (there are standards and then there are Standards), WHERE (a variety of HCI standards are coming from a variety of groups), WHEN (standard development takes time), WHY (standards are inevitable). It then discusses HOW these standards will effect HCI developers and in particular the HCI design process and compliance with HCI standards. It concludes with agendas of standard related activities both for HCI standardizers and for HCI development organizations.
Relative Contribution of Training and Interface Design to Mental Model Assimilation BIBA 453-457
  Peter H. Jones; David W. Biers
The purpose of the study was to determine the relative efficacy of training (advance organizers) and interface design in the formation of a mental model of a menu-oriented data base management system. The study employed a 2 X 5 factorial between-subjects design with two levels of Menu Interface (Data vs. Task) and 5 levels of Advance Organizers (None, Functional Job Description, Spatial Menu Map, Data Menu Map, Task Menu Map). Subjects engaged in a series of tasks which simulated the operation of a video store. Results indicated that the task-oriented menu interface resulted in less task completion time, fewer errors, and greater lexical model assimilation than did the data-oriented menu interface. There were no significant differences in these same measures as a function of advance organizer condition (training). This suggests that the actual interface itself may have more to do with the formation of a mental model and that some interface designs lead to better assimilation of the system model than do others. The failure to obtain an effect of advance organizers was attributed to lack of use of the training material, task and interface simplicity, and subject familiarity with the task domain.

COMPUTER SYSTEMS: Designing Control Rooms for the Year 2000: New Technologies, New Techniques?

Designing Control Rooms for the Year 2000: New Technologies, New Techniques? BIBA 458-459
  Edward L. Cochran
Control rooms are one of the most visible areas of applied human factors, and they represent perhaps the most thorough integration of the various disciplines that comprise the field. Control rooms may well be revolutionized by the turn of the century through the widespread application of technologies that are just now emerging. This symposium will explore, from a variety of perspectives, the technologies likely to affect the next generation of control rooms. We hope to stimulate debate about which emerging technologies are likely to have significant impact, how control room designers should incorporate those technologies in the near term (and plan for them in the long term), and how the enhanced capabilities of the operators of large systems of the future could affect the design of those systems.
Control Room User Interface Technology for the Year 2000: Evolution or Revolution? BIBA 460-464
  Edward L. Cochran
Control rooms -- central facilities used to manage large systems such as industrial processes and communication networks -- are a relatively recent innovation. As the operators of large systems are asked to perform more efficiently, use more sophisticated control systems, and take on more duties and responsibilities, developers of control room equipment have sought to improve operators' ability to interact effectively with their systems. Control rooms have evolved as a result: Pen recorders and mechanical gauges were replaced by text displays on low-resolution monochrome cathode ray tubes, which were in turn supplanted by higher resolution color graphics displays. A new generation of technology now emerging from multiple disciplines will greatly affect control rooms. Some of these technologies, such as bigger displays, improved simulations, and better graphics, represent evolutionary advances. Others, including artificial intelligence technologies such as user intent recognition and context-sensitive aiding, user interface technologies such as virtual reality, multimedia, and true three-dimensional displays, and systems technologies such as object-oriented programming techniques and high-performance communications, may well revolutionize the control rooms of the future, replacing supervisory control with collaborative operations in which the system and the operator will share tasks associated with planning, conducting, and optimizing operations.
The Intelligent Graphic Interface Project: Operator Interfaces for the Year 2000 BIBAK 465-469
  John L. Crawford
Managing a complex computerized process such as a telecommunications network, an electric power system or a pulp and paper mill is an increasingly difficult task. Developing effective human-computer interfaces for the supervisory control centres of the future requires an interdisciplinary approach, applying research results from a range of academic disciplines to the real-life problems faced by industrial users of the technology. This is the approach of the Intelligent Graphic Interface (IGI) Research Project, a unique applied research project linking Canadian industry and academic communities. The goal of this five-year, $6.8 million project, which began in 1991, is to combine artificial intelligence research with advanced computer graphics technology and human factors engineering to produce an Intelligent Graphic Interface; essentially an "expert assistant" for operators in real-time supervisory control environments, dedicated to enhancing the interactions between people and these complex computerized systems.
Keywords: Computer graphics, Real-time expert systems, Human factors, Supervisory control
Evolution of Control Rooms from Low Tech to High Tech: What Do We Do with All that New Technology? BIB --
  Christine M. Mitchell
Graphical Interfaces to Complex Systems: Separating the Wheat from the Chaff BIBA 470-474
  John M. Flach; Kevin B. Bennett
There seems to be a clear consensus that graphical interfaces provide an opportunity to integrate data from complex process in a way that can greatly enhance the problem solving ability of human operators in the future. However, this consensus is masked by a proliferation of terms to express this position in the basic and applied research literatures (e.g., "integrality," "configurality," "proximity-compatibility," "visual momentum," "direct manipulation," and "ecological interface"). While the subtle nuances that distinguish among these terms are of academic interest, designers have greater concern for the general principles that might be gleaned from across the subtle distinctions. Base on a thorough review of the basic and applied literature (Bennett & Flach, In press), we argue that there is one basic characteristic of graphical representations that is critical for supporting problem solving. A good graphical display is one whose geometric (space/time) constraints reflect the functional constraints in the process being represented. In this presentation, we will demonstrate what we mean by a "functional constraint" in a process and a "geometric constraint" in a display. We will demonstrate alternative mappings from "functional constraints" to "geometric constraints." We will also discuss the implications of these mappings for the type of processing (cognitive versus perceptual) required of the human operator.

CONSUMER PRODUCTS: Automotive Applications

The Design of Automotive Acoustic Environments: Using Subjective Methods to Improve Engine Sound Quality BIBA 475-479
  Norman C. Otto; Gregory H. Wakefield
The sensory environment of the vehicle is an area where customer expectations have greatly increased in recent years. For example, sound quality has become a very important factor in determining customer perception of vehicle quality and value. In this paper, a method for evaluating sound quality is presented and used in an engine design application. As part of the design of a future midsize vehicle, 14 engine component modifications were being considered as ways to improve sound quality. A subjective evaluation was carried out to determine if these modifications had any effect on perceived sound quality and, if so, which modifications provided the greatest sound quality benefit. A paired comparison method was used in which subjects judged, first, similarity and, then, preference. The similarity results showed that the vehicle sounds were indeed perceived quite differently. Additional analysis, using multidimensional scaling, revealed that most of these differences could be attributed to just three of the modifications (lightweight valvetrain, crankshaft counterweight, and accessory drive). The preference results confirmed that these three components also governed the valuative judgements. As a result of this study, these modified components were included in the final vehicle design. More generally, the subjective evaluation and analysis procedure described here offers a means for bringing human factors into the design of automotive acoustic environments.
A Pilot Study of the In-Vehicle Safety Advisory and Warning System (IVSAWS) Driver-Alert Warning System Design BIBA 480-484
  Jason Erlichman
This pilot study was conducted to obtain preliminary information regarding alternative signalling presentations and symbologies for the Driver-Alert Warning System design within the In-Vehicle Safety Advisory and Warning System Program sponsored by the Federal Highway Administration. Preliminary analysis had been conducted by both Hughes Aircraft Company and The University of Michigan Transportation Research Institute. The pilot study concentrated of the driver attributes of understanding, relative effectiveness and signalling format. Thirteen subjects were exposed to the new pictograms prototyped on a Macintosh computer and were requested to verbalize their understanding and preferences in regard to varying signalling characteristics. These characteristics included, a) monochrome, b) color, c) blink, d) tone, e) text message and f) voice message. The results indicated that, as a group, the combination of color, audio tone, text and voice message was the preferred signalling presentation. Gender differences were noted with the female subjects indicating a preference for the combination that included color and blink. All pictograms were recognizable by the subjects and all subjects agreed that IVSAWS would be a substantial aid to the driver.
Power Window Control Location Stereotypes BIBA 485-489
  O'Seong Kweon; Robert E. Schlegel; Jerry L. Purswell
A paper-and-pencil survey instrument and an operational test were used to assess stereotype strength for automobile power window controls. Control panel layout (square vs. linear) and mounting plane were examined along with stereotype differences between subjects with technical backgrounds and those with non-technical backgrounds.
   A total of 273 participants ranging in age from 16 to 50 completed the survey instrument which requested responses to questions about which control was expected to activate a specified window. Subject preference for a particular control configuration was also solicited. A square control layout mounted on the instrument panel exhibited the strongest stereotype (94% of consistent responses for a single pattern) although it was the least preferred (22%). A square configuration mounted on the door panel possessed the second strongest stereotype (67% and 28% of consistent responses for the top two response patterns) and the highest preference (47%). A linear configuration mounted on the door panel exhibited a weaker stereotype (57% and 36% of consistent responses for the top two response patterns) and was preferred by 31% of the subjects. Preference tended to follow familiarity with controls in existing vehicles rather than ease of use or isomorphic arrangement.
   Twenty-four of the survey participants were also tested using actual power window controls mounted in a vehicle mockup. The subject's task involved moving the left hand as quickly as possible from the steering wheel to the subject's selected control upon presentation of a pictorial or verbal cue to raise or lower a specific window. Cue presentation and measurement of reaction time and movement time were provided by a PC. The square control layout mounted on the instrument panel was superior in terms of response time, stereotype strength and response consistency.
Menu System Suited to Novice and Experienced Users of an Automobile Navigation System BIBA 490-493
  Beth A. Loring; Michael E. Wiklund; Clark Smith
Computer-based products require designers to make trade-offs between the product's initial and long term ease of use. The trade-off decisions are particularly important in the design of a computer-based automobile navigation system (ANS). An ANS designed for the mass market must serve the needs of both first time users, such as rental car drivers, and those who may purchase cars equipped with the device and use it on a daily basis. In our efforts to design the user interface to an ANS, we sought a means to protect new users from advanced functions that would frustrate the early learning experience. At the same time, we sought a smooth method for everyday users to access advanced functions. In this paper, we briefly explain automobile navigation systems, and then discuss our design solution.


Components of Perceived Risk for Consumer Products BIBA 494-498
  Kent P. Vaubel; Stephen L. Young
The present study examined the underlying dimensions associated with perceived risk for consumer products. Eighty undergraduate students evaluated 40 products using seventeen rating questions. Principal components analysis was then performed on the ratings. Results indicated the presence of three underlying components or dimensions along which the products varied. The first component dealt with qualitative aspects of the risks associated with a product, such as the degree to which potential hazards were known (or knowable) and the immediacy of their onset. The second component concerned subjects' familiarity with the product. The third component was associated with quantitative aspects of the risks and reflected notions about the magnitude of the potential harm (in terms of the number of potential victims) that might be incurred as a result of using the product. Subsequent regression analyses revealed that each dimension was significantly related to subjects' rated intent to act cautiously with a product. Overall, these results suggest that people do not perceive consumer products unidimensionally. Rather, such perceptions are best conceptualized as reflecting multiple underlying facets.
A Methodological Taxonomy for Warnings Research BIBA 499-503
  Thomas J. Ayres; Madeleine M. Gross; Donald P. Horst; J. Neil Robinson
Beginning with several empirical papers in the late 1970's, there has been considerable research concerned with assessing the effectiveness of such attempted safety interventions as on-product warnings and safety signs. The focus of research on warnings has shifted from a debate on whether warnings work to systematic investigation of the factors that do or could influence safety-related product-user behavior. From the perspective of safety, the logical test of a warning must be reduction of the frequency and/or severity of accidents and injuries. A taxonomy of available research methods is described; strengths and problems associated with each method are discussed. Although research on topics related to warnings may legitimately address a wide variety of psychological issues, informed safety policy-making should rely primarily on well-controlled real-world studies. Within the restricted aim of making unambiguous contributions to generalizations that can inform safety policy, some methodological cautions are appropriate for both researchers and practitioners.
Effects of Two Type Density Characteristics on the Legibility of Print BIBA 504-508
  Stephen L. Young; Kenneth R. Laughery; Marilyn Bell
A great deal of research exists regarding the likelihood that warning information will be noticed, but much less research has examined the conditions under which warnings are likely to be read. One variable that may influence the ability and willingness of people to read text is legibility. Poor legibility may result in the information being more difficult to read and thus be a deterrent to reading it. An important determinant of legibility is print density. The present study examined the effect of two print density manipulations, type width and inter-character spacing, on the ease with which warnings could be read. Subjects selected the more "readable" of two choices in a paired comparison task involving all possible combinations of type width (35% of normal, 60% of normal and 100%) and inter-character spacing (10% of normal, 50% and 90%). Results demonstrated that subjects preferred the 100% type width followed by the 60% and then the 35% widths. There was no main effect of inter-character spacing, although spacing did interact with type width. In a subsequent reading-speed task, it was shown that the smallest print condition (with the 35% width and 10% inter-character spacing) produced significantly longer reading times than either the intermediate or larger print conditions. Overall, these results suggest that type width is a strong determinant of print legibility, and that it can be manipulated to increase the ease with which warning information is accessed.

CONSUMER PRODUCTS: Product Applications

Operation of Controls on Everyday Products BIBA 509-513
  W. Schoorlemmer; H. Kanis
Previous research shows that the self-reliance of physically impaired people can be seriously jeopardized by their inability to operate controls on everyday products. In the research reported in this paper a study is made into the operational difficulties faced by people suffering from Parkinson's disease, from spasticism, from visual impairments, and by physically non-impaired subjects.
   This paper reports the forces that can be exerted by these subjests, the way they actually manipulate controls, and the operational difficulties the subjects experience including both the force exertion and other operational difficulties. Finally, design implications are briefly looked into.
Effectiveness of the C-Sharp for Reducing Ergonomic Problems at VDT Workstations BIBA 514-518
  Jennie J. Gallimore; Michael E. Brown; Timothy P. Clarkston; Paul A. Petachi
The C-Sharp was designed to help reduce some of the ergonomic problems associated with long-term use of visual display terminal (VDT) workstations. The C-Sharp projects the viewed image at a farther distance than typical VDTs to reduce the amount of muscular work involved in accommodation and convergence to near targets. This may help to reduce or eliminate visual strain and temporary myopia. It was also designed to eliminate glare. The present study was conducted to evaluate the C-Sharp from a human factors standpoint and to assess its ability to reduce problems related to VDT use. Results indicate that the C-Sharp meets many of the recommendations of the American National Standard for Human Factors Engineering of Visual Display Terminal Workstations. The C-Sharp also allows bifocal wearers to keep their necks in natural postures rather than tilted backwards. In general, the C-Sharp has potential to reduce problems associated with VDT use.
Shoe Cushioning and Related Material Properties BIBA 519-522
  Ravindra S. Goonetilleke; Jennifer A. Himmelsbach
This study investigated the effect of dynamic material properties on the Perceived Level of Cushioning (PLC) in shoes. An Impact Tester was used to characterize the material properties. Three pairs of shoes were used in the two experiments conducted. Experiment 1 was aimed at establishing the effects during standing while experiment 2 was an attempt to relate the effects during walking. A 7-point scale was used to rate PLC. The results showed that during standing, PLC may be related to stiffness of the material, compression, and the time to reach maximum deceleration. However, during walking, PLC appears to be related to the maximum deceleration as measured by the Impact Tester.
A Computer Keyboard Key Feel Study in Performance and Preference BIBA 523-527
  Kenichi Akagi
A study was conducted to compare user preference and performance of four keyboards having different key force and travel characteristics. Two keyboards had linear spring key action, one with low (key force) resistance (42.5 grams) and one with high resistance (70.9 grams). The other two keyboards had tactile (snap) action, one with low resistance (35.5 grams) and one with high resistance (70.9 grams). All four keyboards were manufactured by the same company, and were visually identical in size, layout, color, etc. There was no difference in typing sound and traveling distance among the four keyboards. Twenty four touch typists typed material taken from a college psychology textbook for seven to eight minutes on each keyboard. Between changing keyboards, the participants rested one minute. The two low resistance (35.5 grams tactile, 42.5 grams linear spring action) keyboards produced 23.3% more errors (57% of total errors) than the two high resistance keyboards (43% of total errors). There was a 10.28% difference in errors between the low resistance spring and the low tactile action keyboards, and there was only a 2.95% difference in error between the high resistance spring and the high resistance tactile action keyboards. The lighter the key resistance, the more errors were produced. The average typing speed of all of the participants indicated that there was no significant typing speed difference among the four keyboards. The keyboards preferred by the participants were almost evenly distributed among the low resistance linear (42.5 grams, 29% of participants), the low resistance tactile (35.5 grams, 29% of participants) and the high resistance tactile (70.9 grams, 25% of participants) keyboards. The high resistance linear (70.9 grams, 17% of participants) keyboard was chosen least.

CONSUMER PRODUCTS: Labeling for Food and Beverages

Connoted Quantity of Food-Label Modifier Terms BIBA 528-532
  Michael J. Kalsher; Michael S. Wogalter; Carolyn M. Gilbert
This descriptive study examined a set of modifier terms (e.g., reduced, enriched) that might be used to indicate amounts of substances in food products. In the context of a mock shopping task, participants were asked to complete a survey that assessed the implied meaning of each of 55 terms, 28 connoting varying degrees of decrease and 27 connoting increase. For each set of modifier terms, participants estimated the amount that each term implied and the likelihood that they would purchase a food product with the term paired with substances that they were advised to consume or avoid. The results showed that the terms used in this study connoted a broad range of quantities. Several alternative terms not currently used or under consideration by the U.S. Food and Drug Administration may be effective in helping consumers make finer distinctions among products and, presumably, wiser purchase decisions. The results also suggest that caution be exercised when selecting modifier terms since some terms are less consistent in their connoted meaning than others. Thus, instead of arbitrarily selecting modifier terms and then initiating expensive, large-scale nutrition training programs to train the public, it is recommended that a limited number of modifier terms based on their extant meaning to a broad segment of the population should be used. Future research on developing an optimal set of modifier terms is discussed.
The Influence of Audio-Video Instruction on Consumers' Selection of Nutritious Food Products BIBA 533-537
  Diane M. Jessen; Michael S. Wogalter
The present research investigates procedures for educating people on the use of nutritional labeling. The methods incorporate instructional audio-video media in conjunction with active decision making and immediate feedback. Three groups of participants (audio-video only, audio-video plus active decision making/feedback, and no-instruction control) were asked to chose the more nutritious products from pairs of similar products based on the information on the labels. The results showed that audio-video media improved the accuracy of the product-pair selections and nutrition knowledge. No additional benefit of active decision making and feedback was found. A follow-up product choice test given approximately one week later showed that performance for the two audio-video conditions was maintained, but there were no differences between conditions primarily because of a nonsignificant increase by the control group. However, the follow-up testing showed that the two audio-video groups had greater nutrition knowledge than the control group. Additional analyses showed that demographic variables such as gender, occupation, income level, health status, and special diet were related to product-choice and nutrition test performance. This research advances empirical work in this area, first, by showing an effective and efficient way to educate the public on nutrition and food label information, and second, by employing a performance measure (consumer choice) that might be useful in future research examining differences between food label formats and education strategies.
Effects of Processing Depth on Memory for the Alcohol Warning Label BIBA 538-542
  David P. MacKinnon; Alan W. Stacy; Liva Nohre; R. Edward Geiselman
The experiment examined: (1) the effects of different types of processing of the alcohol beverage warning label on memory for the label content, (2) potential measures of memory for the alcohol warning label, and (3) whether cues to the alcohol warning label increase memory for the content of the label. We hypothesized that the warning label may be processed in three ways: (1) persons may read the label, (2) persons may read the label and describe its content to others, and (3) persons may see the label but not cognitively process the label. Processing effects were operationalized as three orienting tasks to the label (read, paraphrase, and count) which were compared to a control condition (no experimental exposure to the warning label). Four tests (free recall, recognition, word-stem completion, and controlled association) were compared. In one additional condition, subjects were cued to the warning label without prior experimental exposure. The free recall test was the most sensitive measure to different levels of processing. Average memory scores for the paraphrase and read conditions were higher than the count and control conditions. Average memory performance in the cued condition was superior to the control condition, suggesting that subjects remember the content of the warning from exposure to the label outside this experiment.


Innovative Ideas for Laboratory Exercises BIBA 543
  S. Deivanayagam; Ram R. Bishu; Andris Freivalds; Paul Green; Chin Lee
The panel session is designed to provide a forum for educators to exchange information about the laboratory class exercises. It was observed at the Educators Professional Group there are many common features in the first course taught in human factors/ergonomics area across the nation. The requirement of laboratory experience is one such common feature. The importance of the panel session can be stated in terms of the benefits for all human factors educators. The laboratory experience forms an important and effective component of human factors education. Curriculum updating is a continuous process and educators are always seeking innovative ideas and effective means of delivering the subject matter. The panel session, it is hoped, will serve the purposes of curriculum improvement and delivery in a small but definite way.

EDUCATORS' PROFESSIONAL: Educational Issues in Human Factors

The Dictionary for Human Factors/Ergonomics: A Significant Reference Work in Human Factors BIBA 544-547
  James H., Jr. Stramler
Terminology is probably the most important factor in learning or working in any field. The Dictionary for Human Factors/Ergonomics is the result of a major effort to prove the first single source containing a large proportion of the terms used in all areas of human factors/ergonomics. A number of benefits accrue from having this work available. Some of the problems encountered in writing this dictionary are discussed. The ultimate goal for this work is to serve as a terminology standard in human factors/ergonomics.
Human Factors and Educational Quality BIBA 548-552
  Barrett S. Caldwell
This paper discusses the demands on and by universities to update and improve educational delivery in an increasingly difficult economic context. The actions of a number of universities consider the criteria of Total Quality Management (TQM) as a strategy for improving educational quality. However, from a human factors approach, the most immediately obvious types of quality interventions may prove inadequate to address the complexity of the instructional space setting. Drawing on a combination of previous and current work in the field of educational quality improvement, the author addresses the need for an integrated human factors approach that includes ergonomic, aesthetic, and facilities management issues. Such an approach is largely absent from the research and applications literature. Much of the existing knowledge applicable from a human factors standpoint is isolated and fragmented, and does not address the classroom as a complex system. The author also presents the concept of a Classroom and Laboratory Instructional Quality (CLIQ) evaluation facility which can contribute a realistic and effective educational experience for future generations of human factors professionals. The CLIQ facility, while providing important research and training experience, can also serve large numbers of undergraduate students by identifying quality improvement strategies to enhance current and future classrooms and other instructional spaces.
Integrated Workstations for the Instruction of Job Design and Evaluation BIBA 553-555
  Andris Freivalds; Joseph H. Goldberg
There are pressing needs to enhance the quality of undergraduate engineering instruction, including human factors engineering. Specific curricular and philosophical issues include: 1) Integration of Work Measurement and Human Factors, 2) Applications driven laboratories, 3) Open-ended problems, 4) Compartmentalization of knowledge, 5) White-collar work. In summary, the end goals of this laboratory development are innovative job design and evaluation workstations, which can provide students with real-world, open-ended problems.
   Two different workstations are proposed: a workstation appropriate for typical blue-collar assembly work and a workstation appropriate for white-collar computer driven work. The white-collar workstation will simulate modern-computer driven office jobs, and the common factors influencing their productivity, such as speed, accuracy, noise, illumination, etc. The blue-collar workstation would be centered around a typical assembly process found in the U.S. automotive industry. Specifically, carburetor assembly will be utilized because of the large number of fairly intricate parts, the highly repetitive and rapid assembly process, and the need for power driven tools. These also happen to be the prime factors that are thought to increase the incidence of cumulative trauma disorders in U.S. industry. The students will examine tool parameters, and be able to adjust the support of the tool with tool balancers, cut the detrimental impact of power tools on the hand, using the reaction torque bars and implement novel approaches, such as arm rests or arm slings as used in Sweden.
Introductory Human Factors Engineering Courses: What is Currently Taught BIBA 556-560
  R. Darin Ellis; Joseph H. Goldberg
Course syllabi were requested from 43 U.S. undergraduate engineering programs to assess the structure and content of introductory Human Factors Engineering courses. Such information is valuable for new faculty and those who want to redesign their courses. Educators in industry also must constantly evaluate their courses to ensure their material is current. Syllabi were received from 27 of the programs. Factors considered were textbooks, credits, ABET credit categories, grading, and TA usage. Course topics were analyzed by frequency of appearance across the courses. The most popular topics were vision and hearing-related, displays, anthropometry, and workspace evaluation and design. Less popular topics, included liability, technical writing, shiftwork, and occupational stress.


First Course in Human Factors Engineering: What Should be Taught? BIBA 561-562
  Joseph H. Goldberg; Paul C. Champney; Keith S. Karn; Michael W. Riley; Brian Peacock
Industry and academia often have differing desires in the introductory Human Factors education of engineering students. Industry seeks solutions to current problems, whereas academia can communicate state-of-the-art concepts without immediate application. This panel session united members of academia and industry for discussion of what topics and structure should underlie a one-semester, introductory, survey course in Human Factors Engineering. Each panel member expressed his opinion of what should be in such a course, followed by discussion aimed at achieving consensus of opinions.

EDUCATORS' PROFESSIONAL: Increasing the Breadth of the Human Factors Scientist-Practitioner

Increasing the Breadth of the Human Factors Scientist-Practitioner BIBA 563-565
  Curt C. Braun
It has been 40 years since the Department of Defense first commissioned the development of the Human Engineering Guide to Equipment Design. In this, the 40th anniversary year, it is fitting to examine the training of human factors purveyors and provide suggestions for supplemental training where little formal training exists. Review of current human factors education programs reveals that many of the published guidelines are, to a greater degree, being fulfilled. These findings should be encouraging, yet human factors educators, students, and practitioners alike are hesitant to conclude that psychologists or human factors specialists are necessarily complete upon attaining these skills. Many newly graduated human factors practitioners, while competent in human processes, do not possess the skills and background necessary to perform in a variety of domains. The goal of this symposium is to address the issues of human factors training by providing curriculum material designed to build upon fundamental skills.
Foundations of Human Factors BIB --
  Peter J. McAlindon; Paul B. Kline
The Expert Witness BIBA 566-567
  Jeanne L. Weaver; Jada D. Kearns; Julie M. Urban
Although human factors principles have become increasingly well accepted within the legal community, there are new human factors professionals who have little familiarity with the expert witnessing process. While there are other sources which address specific issues related to forensic psychology, this paper seeks to provide a broad overview of related topics. Among the topics discussed are ethical considerations, information regarding the legal process, and suggestions regarding courtroom presentation.
A Human Factors Tool Kit BIBA 568-571
  Paul B. Kline; Peter J. McAlindon
The variety of tools and techniques available to help the human factors professional apply basic research data to the real world is constantly increasing. Despite this, there are few available sources of objective information about tools. Most of the information available to practitioners comes in the form of advertisements and professional contacts. Unfortunately, the emphasis is often on newest or latest when less expensive 'low tech' solutions may work just as well. Moreover, there are likely tools or techniques known to practitioners in one area of the human factors that are unknown to individuals in other areas of the discipline. The current effort seeks to identify tools useful to the human factors professional and to increase awareness of existing tools which can facilitate the application of Human Factors data to the real world. An added emphasis was placed on those tools which can be employed easily and inexpensively.
The Human Factors Toxicologist BIBA 572-574
  Julie M. Urban; Curt C. Braun; Jeanne L. Weaver
Toxicology is a relatively new science in which much work is needed. The human factors professional is uniquely qualified to contribute to this field in a variety of ways. On a long-term basis, the work of the human factors professional is needed for a) the development of appropriate testing procedures to identify situations of unknown exposure, and b) the monitoring of research on the effects of specific toxins to serve the basis of legal exposure standards. There is also an immediate need for the human factors professional's knowledge of systems integration, design, and training to protect the human from the toxins to which he/she may be currently exposed in a variety of environments.


Interactions between Environmental Design and Human Factors Specialists BIBA 575-577
  G. F. McVey; Daniel E. McCrobie; Deane Evans; H. McIlvaine Parsons; John A. Templar; Stephan Konz; Barrett S. Caldwell
Most of the interactions between human factors specialists, such as ergonomists, and environmental specialists such as facility planners and architects tend to be task specific and do not follow any accepted process. Consequently, the success of such interactions are usually a function of serendipity rather than informed expectation. It is anticipated that by gathering such specialists in an open discussion, relevant issues may be addressed and successful interaction procedures introduced and discussed. Such a forum is desirable for developing an understanding of the differences, educational and operational, between environmental design specialists, and human factors specialists, as well as for exploring the ways their communications can be enhanced. It is anticipated that by sharing their experiences with the attendees, the presenters will identify relevant on-going knowledge transfer activities, and also introduce and discuss practical problem-solving and communication methods that can be used with assurance by the attendees themselves when faced with similar problems in the future.
   This panel will focus on issues that arrive out of situations where human factors specialists and environmental design specialists are joined together in project development. The specialties represented include architecture, facility planning, environmental psychology, ergonomic research, industrial design and engineering, and equipment and furniture design and manufacturing.

ENVIRONMENTAL DESIGN: Planning for Environmental Design and Follow-Up Evaluations

In the Era of ADA, Do We Really Have Accessible Bathrooms: A Survey BIBA 578-581
  Pascal Malassigne; Thomas L. Amerson
A postal opinion survey examined several issues related to use of home modifications, bathrooms and bathroom fixtures by 783 adults with disabilities. Key research issues included the following questions:
  • 1. What are the types of approaches and transfers to bathtubs and toilets made
        by non-ambulatory people, and how do they differ from the approaches and
        transfers of those who are semi-ambulatory?
  • 2. How effective are grab-bars in transferring to and from the bathtub or the
  • 3. What are the design features of the lavatory which are liked or disliked by
        semi and non-ambulatory users? Of those responding to the questionnaire, 60% were older than 50 years of age; so the opinions or experiences expressed may be more reflective of an older population. Of the non-ambulatory respondents, 83% used a manual chair and 17% used an electric wheelchair. Among semi-ambulatory respondents, 28% used a cane or crutches for assistance. Most respondents lived with family, and modifications were made in 69% of these homes to enhance independence in daily activities. Nearly half of the respondents were unsatisfied with their bathroom fixtures. Although there was a relatively wide range of responses depending upon the type of disability impairment of respondents, strong preferences (or dislikes) were noted for fixture designs.
  • AutoNet: An Application of a Neural Network Simulation as a Tool for Planning Office Layout BIBA 582-585
      Michael J. O'Neill
    When people have trouble finding their way through office gettings, there are costs in terms of poor communication, lost efficiency, time, and stress (Brill, et. al., 1984; O'Neill, 1991; Weisman, 1981; Zimring, 1981). To cope with wayfinding problems, facilities managers often have to resort to partial solutions, like complex signage, color coding schemes, and other methods to guide people. AutoNet is an experimental computer-aided design and planning tool that predicts the paths people will take through a building based on the layout of the space and their level of experience. AutoNet represents environmental information by using an artificial 'neural network' simulation. The mechanisms of this simulation are based on the physiology of the brain. Knowledge about the layout of the environment is represented through a network of interconnected processing elements, modeled on the behavior of groups of neurons in the brain. Thus it can create its own rules for predicting worker behavior rather than using predetermined sets of rules that a typical expert system would rely on. This system has great flexibility since there are no rules to rewrite for each setting it evaluates. The predictive validity of this simulation was empirically validated (O'Neill, 1991). This software runs within a popular and commonly available CAD software package in an MS-DOS environment. AutoNet is viewed as a "macro-ergonomic" tool to enhance the office work environment (Hedge & Ellis, 1990).
    User Assessments of Selected Lecture Halls and the Relative Merits of Architectural Standards and Ergonomic Guidelines BIBA 586-590
      G. F. McVey; James D. Bethune
    In two studies spanning approximately twenty years, two investigators employed a nearly identical user assessment instrument (questionnaire) in the evaluation of college lecture halls. The results of both of these studies, although performed approximately twenty years apart, indicate the firm and continuing existence of a strong and statistically significant student preference for lecture halls designed and constructed in accordance with ergonomic guidelines, in addition to standard architectural practices and prevailing building codes, over those designed and constructed in accordance with the architectural standards and prevailing building codes but without observance of ergonomic guidelines. In both studies, an analysis of individual item responses against the physical characteristics of each lecture hall revealed the specific environmental and display system features preferred by the students. Consequently, it is recommended that now and in the future, facility planners and architects make every effort to utilize existing ergonomic guidelines and standards in their educational facility design, construction and remodeling efforts.
    Environmental Evaluation of Control Rooms in Nuclear Power Plants BIBA 591-595
      Shusa Hashimoto; Tadashi Nihei
    In recent years, it has been expected more than before that the indoor environment of control rooms in nuclear power plants will be made more comfortable without inhibiting function. In order to derive the environmental problems of control rooms in nuclear power plants that should be discussed, the design standards and operators' complaints were investigated. As a result, some problems such as unsuitable lighting, noisy acoustics and operators' dissatisfaction with their enclosed circumstances were derived. In order to improve the indoor environments and to establish comprehensive environmental evaluation methodology, experiments on environmental factors such as indoor view, noise level, glare on VDU and shift time-zone that were thought to be related to the above problems were conducted. 6 subjects' psychological, physiological and behavioral responses to their environments were measured in the environmentally changeable laboratory, which was mocked up like a control room. Subjects were imposed to do 2 kinds of VDU tasks. From Principal Component Analysis of the experimental results, some psychological, physiological and behavioral indices for evaluating indoor environments were obtained. Furthermore, the relationship between these indices and environmental factors was obtained by Multiple Regression Analysis. The multiple correlation values shows that the environmental factors were most reflected in the psychological evaluation indices. However, other indices are also important because psychological comfort does not always mean good physiological conditions or good task performance. The space functions of the room as a control room and operator's physicological condition should be considered for comprehensive environmental evaluation. The result shows that the introduction of dark green louver, potted plants/artificial window and noise reduction are desirable in control rooms.


    Forensics Practice -- Headaches and Remedies BIBA 596-597
      Richard J. Hornick; Robert O. Besco; James L. Harris; Kenneth R., Sr. Laughery; Mark S. Sanders
    Attorneys are increasingly using human factors practitioners to perform analyses and to testify as expert witnesses in product liability and personal injury cases. Previous panels and symposia have addressed a variety of technical considerations and applications in those arenas. However, there are many practical challenges in providing such services to the legal community in an effective and personally satisfying manner. This panel is focused on the practical matters faced by the individual human factors consultant providing services to the legal community. The panel is intended to explore different experiential perspectives regarding effective procedures for dealing with the unique demands of the litigation field.

    FORENSICS PROFESSIONAL: Warnings and Hazard Prevention

    Swimming Pool Diving Accidents: Human Factors Analyses of Case Study Data BIBA 598-602
      Kenneth R. Laughery; Stephen L. Young; Anna Rowe
    As many as 350 serious spinal cord injuries occur in the United States every year as a result of diving into swimming pools. While there is substantial data on the demographics of injured divers and the events surrounding their injuries, there has been little analysis of the human factors issues associated with this type of accident. Data from 12 swimming pool diving accidents were analyzed in terms of their human factors issues, and the data revealed a number of consistent findings. By virtue of the fact that pools are fairly common, people generally perceive them to be safe. Compounding this sense of security are several interesting perceptual issues about the water depth and the potential risks. People inherently overestimate distances under water, and this effect is exacerbated by cloudy water. Also, all of the divers in this study were young males, who tend to be excessively optimistic and who hold an unrealistic sense of control over potential hazards. This characteristic of male divers was substantiated by the fact that, even when they knew the water was shallow, they unsuccessfully attempted a "shallow dive". In addition to these perceptions and control factors, there appears to be a lack of appreciation of the hazards associated with diving into swimming pools. Quadriplegia or death are not commonly perceived to be a consequence of diving. Several suggestions are offered which could lead to a reduction in the number and magnitude of swimming pool diving accidents. One approach is to provide an appreciation of the hazards and consequences associated with diving so people can exercise reasonable judgment about when and where to dive.
    Effects of an Aversive Vicarious Experience and Modelling on Perceived Risk and Self-Protective Behavior BIBA 603-607
      Evangeline A. Chy-Dejoras
    A 2 x 3 between-subjects design was used to determine the effects of modelling and aversiveness of a vicarious experience on perceived risk and self-protective behavior. Modelling and aversiveness of experience were manipulated using an instructional videotape. Unprotected model and protected model conditions were compared. Benign, slightly aversive, and highly aversive conditions were compared. The dependent variables were self-protective behavior and perceptions regarding the hazardousness of the product, severity of injury, likelihood of injury, likelihood of an accident, and familiarity with the product.
       More subjects in the protected model group exhibited self-protective behavior compared to the control group. There was no difference in levels of perceived risk between the two groups. Aversiveness had an effect on self-protective behavior. The slightly aversive group showed an incidence of self-protective behavior significantly greater than that of the control group and the highly aversive group. Examination of the nature of manipulation used in the slightly aversive condition suggests that an ambiguous portrayal of the consequences of a hazard while implying its potential to inflict harm causes people to behave cautiously. The incidence of self-protective behavior in the highly aversive group did not differ significantly from that of the control group despite a significant difference in perceived levels of hazardousness. This is explained as a manifestation of the so-called "self-protective attribution of responsibility." Perceived hazardousness was found to be the primary predictor of self-protective behavior. Perceived severity and likelihood of injury were found to be the primary predictors of perceived hazardousness. A strong association was found between self-protective behavior and perceived personal susceptibility to injury.
    Warning Compliance: Effects of a Video Warning Sign and Modeling on Behavior BIBA 608-610
      Bernadette M. Racicot; Michael S. Wogalter
    The effectiveness of warnings and social influence (modeling) for improving safety behavior was examined in a laboratory setting. Although training programs aimed at improving safety behavior in the workplace frequently use videotapes with models portraying safe and unsafe behaviors, the effectiveness of training interventions of this type are rarely evaluated nor have results been published in the research literature. Training to increase safety behaviors can translate into large savings to an organization in terms of reductions in equipment damage, cost of liability litigation, and decreases in injury to both consumers and employees. The present research examined the effects of a posted (video) warning, video role-modeling, and a voice warning on compliance with safety behaviors. Participants were randomly assigned to one of three conditions, warning alone, warning and exposure to a video model performing the appropriate safety behaviors, or warning, video modeling, and a voice warning. The results showed that behavioral modeling presented through a video display significantly enhanced behavioral compliance compared to a video sign warning alone. The addition of a voice warning did not further increase compliance due to ceiling effects produced by the powerful influence of the modeling. Implications of this research for safety training programs and forensic human factors as well as suggestions for future research are discussed.
    A Warning Label for Scaffold Users BIBA 611-615
      Daniel Johnson
    The purpose of this research project was to develop a warning label which would: a) alert scaffold workers to the potential of danger when working on scaffolds, and b) to increase the likelihood they would seek out and read the safety guidelines supplied with the scaffolds. A warning was developed and tested on 150 potential users. It significantly increased subjects' behavioral intentions to seek safety information before working on a scaffold they had not been on before. This was true for inexperienced and experienced scaffold workers. This effect was not found for scaffolds the subjects supposedly had been on before. Highly experienced workers were less likely to comply with the warning than less experienced workers. It was concluded that the warning would increase the use of safety guidelines by those working on a scaffold that was new to them. But a new warning on a scaffold a worker had already been on would have no effect on the reading of safety guidelines.

    FORENSICS PROFESSIONAL: Real-World Problems and Practices in Forensics

    Qualifying as an Expert Witness and a Perspective on Negligence BIBA 616-620
      Leighton L. Smith
    This article discusses the process of qualifying as an expert witness in court cases. The author's personal experience as a human factors expert witness in a representative case is described and used as an illustrative example. The role of the expert witness in typical injury litigations is described. The difficulty in convincing judges to allow such testimony by experts is also discussed. The value of human factors expert witness testimony is shown through the particulars of an inadvertent landing gear retraction accident lawsuit. In addition, a discussion of the negligence phase of these types of litigations is provided and it is demonstrated again using the landing gear case as illustration, how human factors expert witness testimony can be extremely integral to the judgment of negligence.
    The Application of an Expanded Accident Sequence Model to Forensic Human Factors BIBA 621-625
      Gary D. Sloan
    There are several models that assist the human factors specialist in identifying those behaviors that most likely contributed to an accident's occurrence. Of particular importance to forensic human factors specialists are models that can also serve as demonstrative aids in communicating the bases of their opinions to jurors. One such aid is a version of Ramsey's (1978) accident sequence model. The model, which has been expanded by the author, traces sequentially the activities that likely take place within the individual before an accident occurs. The expanded model prompts the investigator to ask the following questions: (1) Was the hazard detected? (2) If so, was it identified? (3) If correctly identified, were its characteristics perceived accurately? (4) If perception was veridical, was the individual alert to the danger? (5) If alert to the danger, did they appreciate the degree of risk involved? (6) If their assessment of risk was realistic, did the individual want to avoid the hazard? (7) And if they sought to avoid the hazard, could they to do so under the existing conditions? The author draws from cases in which he served as an expert witness to illustrate the model's application.
    The Effects of the Image Factor in Televised Advertising on Consumer Perception BIBA 626-630
      David M. Cohen; H. Harvey Cohen
    A review of the literature suggests that televised commercials display a definite image in presenting their product, and that airing of the commercial will have a predictable effect on consumer perception of the product advertised. The present study involved a questionnaire in which 140 subjects were asked to design a commercial using directed choices for one of four motor vehicle types: a mini-van, a pickup truck, a sports car or a luxury car. The hypothesis was that most subjects would design a commercial that reflected a definite image which would vary amongst vehicle types. Though the results did not support the original hypothesis in all respects, there were patterns of similarity in the responses which led to modification of the hypothesis, that being that image does not dictate the way motor vehicles in the commercials are perceived, but rather it directs the way they are perceived in accordance with viewers' varying needs and desires.

    GENERAL SESSIONS: NAS/NRC Committee on Human Factors: Retrospect and Prospect

    The NAS/NRC Committee on Human Factors: What It is and What It Does BIBA 631-632
      Raymond S. Nickerson
    The National Research Council's Committee on Human Factors attempts to identify human-factors research needs of special interest to its sponsors and of importance to the country as a whole. This paper gives a brief overview of what the committee is and how it functions, by way of introduction to the succeeding presentations, which describe three of its current activities.
    Education, Training, and Training Technologies BIB --
      Joyce L. Shields
    Human Factors Issues in Information Access BIB --
      Christopher D. Wickens
    Emerging Technologies and Work Design BIB --
      Paul A. Attewell

    GENERAL SESSIONS: Environmental Management: Interfaces with Human Factors

    U.S. DOE's Office of Technology Development Solves Environmental Restoration and Waste Management Problems BIBA 633-635
      Donald Beck
    DOE's 30-year goal is, by the year 2019, to clean up its current inventory of inactive sites and facilities and, on a much faster track, bring its nuclear-related sites and facilities into compliance with applicable Federal, State, and local laws and regulations.
       The U.S. DOE Environmental Restoration and Waste Management (EM) Office of Technology Development has program responsibility for providing new and more effective technologies for meeting DOE's 30-year compliance and cleanup goal. The Office of Technology Development seeks to resolve major technical issues and advance rapidly beyond current technologies for Environmental Restoration and Waste Management activities.
    Impact of Operation and Maintenance on the Performance of Energy Systems BIB --
      M. Kevin Drost
    Human Factors in Environmental Management: New Directions from the Hanford Site BIB --
      James A. Wise; S. F. Savage
    What Does Human Factors Research Have to Do with Environmental Management? BIBA 636-639
      Raymond S. Nickerson
    Human factors research has not focused much on the problem of environmental change and its management. The problem has many aspects that interrelate in complex ways. Its roots are in human behavior, so if approaches toward solutions are to be effective, they must involve modifying that behavior or mitigating its detrimental effects. A few suggestions of directions that human-factors efforts aimed at helping manage environmental change might take are made, but the main point of the paper is a plea for more discussion of the topic among human-factors researchers. Such discussion would result, it is assumed, in the identification of specific ways in which the field could contribute significantly to the development of solutions to the problem.

    GENERAL SESSIONS: Human Error and Medical Devices

    Capturing Medical Device Error BIB --
      Marilyn Sue Bogner
    Toward an Agenda for Error Research BIBA 640-643
      Neville Moray
    There has been a great increase in interest in human error and its impact on the individual and society in recent years. The present symposium is but one example of this in a restricted area. Several general accounts of human error and the psychological mechanisms which underlie it have appeared in recent years, but for the most part these have concentrated on accounts of error based on research on the cognitive psychology of the individual. In this paper I discuss a more general framework for the study of error, not for the purpose of understanding it alone, but rather for putting into place a program for mitigating its effect in the larger arena of social impact. Only by integrating research at a variety of levels and using a variety of techniques can we hope to understand and control the effects of error.
    The Link between Design Errors in Human-Computer Interaction, Latent Failures, and System Disaster BIB --
      David D. Woods; Richard I. Cook
    On the Remedies for Medical Error BIB --
      John W. Senders

    INDUSTRIAL ERGONOMICS: Lifting/Manual Material Handling

    Some Ergonomic Considerations in the Design of Material Handling Devices BIBA 644-648
      Marc L. Resnick; Don B. Chaffin
    Material handling devices (MHD's) are being proliferated in factory workplaces to prevent workers from being injured due to the lifting of heavy loads. These devices require exertions which have not been adequately studied from an ergonomic perspective. Jobs with MHDs often require complex 3-dimensional movements and loaded axial rotation. One type of MHD, an articulated arm, was used to investigate the effects of inertial load, arm joint friction, and positioning accuracy requirements. The kinematic variables of peak push and pull hand forces, velocities, and accelerations were measured or computed in both a task that allowed sagittally symmetric postures as well as one in which loaded axial torso rotation was required. Greater inertial loads increased the peak push and pull hand forces in all cases by an average of 20%. The activation of a 40 psi brake at both joints of the articulated arm increased the peak hand forces by about 40% on average and decreased the peak velocities and accelerations in both tasks by about 20% and 15% respectively. The effects of positioning accuracy required were not as universal. There was a 10% decrease in peak velocity and acceleration for smaller target size in the sagittally symmetric task but no significant effect in the torso twisting task. The study generated some guidelines for the implementation of MHD's, and suggests some areas where further research is required.
    Fatigue Effect on Lifting Acceleration in Frequent Lifting BIBAK 649-653
      Y. Kim; K. Lee; F. Aghazadeh
    The objective of this study was to investigate the effects of fatigue, caused by frequent manual lifting, on lifting velocity and lifting acceleration. Ten male volunteers performed lifting at a rate of 4 times per minute, continuously, for two hours using the free-style posture. A box (30cm x 30cm x 20cm) with a fixed weight (15.9 kg) was used as the load for lifting. Heart rate, oxygen consumption, and EMG were also measured to estimate the level of fatigue. The posture as well as acceleration was recorded. The results show that the lifting acceleration at the end of two hour increased significantly (20%, p < 0.001) compared to the acceleration after fifteen minutes of lifting. It was also found that subjects changed their lifting postures as the result of fatigue. All subjects also indicated pain in their upper legs and the lower back at the conclusion of the experiment.
    Keywords: Manual lifting, Lifting acceleration, Muscular fatigue
    Maximum Acceptable Weights of Lift for Common Coal Mine Supply Items BIBA 654-658
      Sean Gallagher; Christopher A. Hamrick
    A series of psychophysical lifting studies was conducted to establish maximum acceptable weights of lift (MAWL) for three supply items commonly handled in underground coal mines (rock dust bags, ventilation stopping blocks, and crib blocks). Each study utilized 12 subjects, all of whom had considerable experience working in underground coal mines. Effects of lifting in four postures (standing, stooping under a 1.5 m ceiling, stooping under a 1.2 m ceiling, and kneeling) were investigated together with four lifting conditions (combinations of lifting symmetry and lifting height). The frequency of lifting was set at 4 per minute, and the task duration was 15 minutes. Posture significantly affected the MAWL for the rock dust bag (standing MAWL was 7% greater than restricted postures and kneeling MAWL was 6.4% less than stooped); however, posture interacted with lifting conditions for both of the other materials. Physiological costs were found to be significantly greater in the stooped postures compared to kneeling for all materials. Other contrasts (standing versus restricted postures, stooping under 1.5 m ceiling versus stooping under 1.2 m ceiling) did not exhibit significantly different levels of energy expenditure. Energy expenditure was significantly affected by vertical lifting height; however, the plane of lifting had little influence on metabolic cost. Recommended acceptable workloads for the three materials are 20.0 kg for the rock dust bag, 16.5 kg for the ventilation stopping block, and 14.7 kg for the crib block. These results suggest that miners are often required to lift supplies that are substantially heavier than psychophysically acceptable lifting limits.
    Implications of the Proposed Revisions in a Draft of the Revised NIOSH Lifting Guide (1991) for Job Redesign: A Field Study BIBA 659-663
      Waldemar Karwowski; Nina Brokaw
    The main objective of this research project was to compare the recommended load limits for lifting tasks derived based on the NIOSH (1981) Lifting Guide and the proposed NIOSH Draft Revisions of (1991). The study involved the following steps: 1) Identification of a total of 15 manual lifting tasks from 8 different jobs performed at the industrial site, with different tasks characteristics in order to cover most of the possible lifting conditions considered under the Draft Revisions to the NIOSH Guide (1991), 2) Description of the lifting tasks variables for the identified jobs, 3) Calculation of the RWL values for the identified jobs per 1991 Lifting Guide, as well as the AL and MPL values according the 1981 Lifting Guide, 4) Comparison of the actual loads lifted (L) with the values of RWL, AL and MPL, and calculation. The results showed that the Draft Guide of 1991 was much more restrictive with respect to defining the lifting acceptable jobs. Under this Guide, 10 out of 15 tasks analyzed in this study (66.7%) were found unacceptable, and required redesigning. For comparison, under the NIOSH (1981) Guide, as many as 8 of 15 (53.3%) of the tasks were found fully acceptable (below the action limit or AL level), while 6 tasks (40%) required application of administrative controls, and only 1 of the 15 tasks analyzed (6.7%) was found unacceptable.

    INDUSTRIAL ERGONOMICS: Strength and Capacity Issues

    Isometric Strength Capability for a Vertical Wheel-Turning Task BIBA 664-668
      Jeffrey C. Woldstad; Christopher J. Rockwell; Christian A. Johnson; Mark McMulkin; Paul B. McMahan
    This paper reports on the measured isometric strength capability of 125 male and 125 female college students performing a one-handed wheel turning task. Three measures of isometric strength were used: (1) a three-second average of steady state levels taken from a six-second exertion, (2) the largest value (peak) from the same six-second exertion, and (3) a maximum exertion level taken from a separate "ramp-to-peak" exertion. Standardized whole-body strength measurements for the legs, arms, and torso as well as grip strength were also taken for each subject. The results presented in this paper demonstrate average isometric wheel turning strengths (torques) ranging from 109 to 152 N-m for males and 66 to 91 N-m for females, depending upon the strength measure used. The three strength measures were highly correlated, but produced significantly different estimates of strength. The three-second average produced the lowest estimate while the ramp-peak value produced the highest. Wheel turning strengths were also highly correlated with the standardized whole-body strength measures and with grip strength. Multiple regression models developed to predict wheel turning strength using these values accounted for 69 to 71 percent of the variation in the measures. The model results also suggest that grip strength plays an important role in determining wheel turning strength capability.
    Effects of Gender, Lift Height, Direction, and Load on the Ability to Estimate Weight BIBA 669-673
      Valerie J. Rice; Marilyn A. Sharp; Tania L. Williamson; Bradley C. Nindl
    The study evaluated the effects of gender, lift height, direction (lift/lower), and load on the ability to correctly estimate weight handled. Seven women and six men lifted and lowered boxes to and from knuckle, waist, and shoulder heights. Subjects were asked to estimate weights corresponding to 50, 40, 30, and 20% of gender specific lifting strength to 152 cm. The difference between the actual and estimated weight (DIFF) was 100% greater for men than for women (F = 6.27, p = 0.03). When the percent difference was analyzed, there was no significant gender effect. The least accurate estimates occurred when lowering a weight from knuckle height (p < 0.05). The majority of subjects underestimated the weight and men underestimated more frequently than women (Chi² = 12.57, p = 0.0004). Subjects over-estimated the weight more often at higher weights. The results suggest that both men and women tend to underestimate weight, especially when lowering from knuckle height, possibly putting them at risk for injury.
    Development of Prediction Models for Physical Work Capacity: Practical and Theoretical Implications BIBA 674-678
      Chris Schacherer; Anna Rowe; Andrew S. Jackson
    The use of pre-employment physical abilities tests has often been criticized as discriminatory to women, older people, and members of certain minority groups. In the present study, body composition (%fat) and VO2 Max were measured in a sample of 771 men and 159 women ranging in age from 21 to 66 years. A hierarchical regression analysis revealed that body composition, age, gender, and the interaction between gender and body composition all accounted for statistically significant proportions of variance in VO2 Max. The results are discussed in terms of their support for the validity of pre-employment physical abilities tests for placement in jobs with a high aerobic component.
    Utilization of Direct Estimation Method to Predict the Maximum Acceptable Weight of Symmetrical and Asymmetrical Lift BIBA 679-683
      Feng Chen; Fereydoun Aghazadeh; Kwan Suk Lee
    The objective of this research was to study the effectiveness and accuracy of using the direct estimation method to determine a worker's lifting capacity or MAWOL of symmetrical and asymmetrical lifting tasks. Sixteen lifting tasks involving four different lifting angles and lifting frequencies were studied. In the first part of the study, ten male subjects performed sixteen lifting tasks to predict the MAWOL for each task condition using the psychophysical method. In the second session of the study, the MAWOL for sixteen task conditions were estimated using the direct estimation method. The results of this study indicate that direct estimation is an accurate method to establish MAWOL quickly for a series of lifting tasks. Analysis of the MAWOLs determined by two different methods indicated no significant difference between these two values. However, a significant difference was found between the direct estimated MAWOLs and the psychophysically predicted MAWOLs at the frequency of 1 lift/min with 30° or 60° asymmetry. This finding indicates as the interval between lifts increases, subjects have difficulty in making accurate estimates of the stress of the specific task, therefor, the direct estimation method should be used with caution.

    INDUSTRIAL ERGONOMICS: Occupational Ergonomics

    Ergonomic Improvement of a Machine Maintenance Procedure: A Case Study BIBA 684-687
      Kelly A. Eckbreth
    An employee who performs maintenance work on machinery used in the manufacture of electronics equipment reported to the company medical department and was diagnosed with elbow tendinitis. An ergonomic job analysis was conducted and solutions implemented to prevent future injuries. Significant improvements were realized as a result of new tools, engineering changes, personal protective equipment, process changes, and ergonomic training. The most significant were the reduction of musculoskeletal stresses suffered by these workers as well as substantial reductions in machine downtime per year.
    Validity of Isometric Strength Tests for Predieting the Capacity to Crack, Open, and Close Industrial Valves BIBA 688-691
      Andrew S. Jackson; Hobart G. Osburn; Kenneth R. Laughery; Kent P. Vaubel
    Cracking, opening, and closing valves are physically demanding tasks required of chemical plant process operators. This study determined if isometric strength tests predicted the capacity to: 1) crack valves; and 2) fully open or close them. The study involved three interrelated steps: 1) complete task analyses to define the torque required to crack valves and the total amount of work required to open or close industrial valves; 2) develop valve turning simulation tests; and 3) complete laboratory studies to define the level of isometric strength demanded for valve turning performance. A total of 405 valves at two major chemical plants were measured to find the torque required to crack, open, and close industrial valves. These data were used to develop two job simulation tests, one measured valve cracking capacity, and the second the endurance needed to open or close a valve. An electronic torque wrench measured valve cracking capacity in eight different ways, and a valve turning ergometer measured the subject's endurance to work for 15 minutes at a power output of 1,413.5 foot-pounds/minute. The sum of isometric grip, arm lift, and torso lift strength tests (ΣIS) measured strength. The isometric strength and endurance work valve tests were administered to 26 men and 25 women. The isometric strength and valve cracking tests were administered to a second sample of 118 men and 66 women. The correlations between ΣIS and work test performance were 0.65 and 0.83 for valve cracking and valve endurance tests respectively. Logistic regression models defined the strength level needed to crack valves and completely close valves.
    MAF for Males Performing Drilling Tasks BIBA 692-696
      Viswanath Vaidyanathan; Jeffrey E. Fernandez
    A laboratory experiment was conducted using the psychophysical approach to determine maximum acceptable frequency (MAF) for a simulated sheet metal drilling task under varying angles of wrist flexion. Fifteen male students served as subjects for this study. The subjects were asked to perform a simulated drilling task in five different wrist flexion postures. Results indicated that MAF was significantly reduced (p<0.001) for deviated wrist postures in the transverse plane. It was noted that there was a 33% decrease in MAF values from 0 degree wrist flexion (neutral posture) to 40 degree wrist flexion. These results imply that industrial guidelines for drilling operations involving wrist flexion must consider the MAFs in order to reduce the risk of cumulative trauma disorders.
    The Evaluation of Occupational Ergonomics Programs BIBA 697-701
      David C. Alexander; Gary B. Orr
    The purpose of this article is to acquaint the reader with alternatives that can be used to evaluate occupational ergonomics programs. These evaluations are helpful in monitoring the effectiveness of the ergonomics program as well as to direct and enhance future efforts. The adage, "You don't manage what you can't measure", describes the purpose of ergonomic program evaluations.
       The benefits of ergonomic program evaluations include:
  • Objective reviews of program content and effectiveness;
  • Specific targeted improvements for program changes;
  • Clear understanding of program goals;
  • More efficient and effective ergonomic programs.
  • INDUSTRIAL ERGONOMICS: Strength/Potpourri

    Reach Posture Prediction of Upper Limb for Ergonomic Workspace Evaluation BIBA 702-706
      Eui S. Jung; Dohyung Kee; Min K. Chung
    Proper assessment of reach posture is one of the essential functions for ergonomic workspace evaluation in CAD systems with a built-in man-model. In this study, each upper limb is modelled as a four-link system, consisting of trunk, upper arm, lower arm, and hand, being regarded as a redundant manipulator with a total of eight degrees of freedom. Inverse kinematics is introduced in this study to predict the trajectory of multi-link segmental movement. Among several kinematic methods for solving the multi-link system, the resolved motion method was found to be effective to solve this redundant manipulator model, and the joint range availability was used as a performance function in order to guarantee local optimality. Real reach postures taken from the subject were analyzed by Motion Analysis System and showed reasonable results when compared to those obtained from the model.
    Predicting the Maximum Acceptable Weight of Lift for an Asymmetrical Combination Task BIBA 707-711
      Tycho K. Fredericks; Jeffrey E. Fernandez; Clarence C. Rodrigues
    This paper presents prediction models based on a study of a combination lift and lower manual handling task that was designed to simulate the loading of grocery bags into a car trunk. Twelve male subjects performed an externally-paced task of lifting plastic grocery bags (with handles) loaded with weights from 15 cm above the floor and over a wooden sill. There were two different sill heights of 70 cm and 90 cm, and for each of these heights there were two frequencies of 3 and 6 lifts per cycle. A unique lifting sequence and a modified version of the psychophysical methodology was used to determine the maximum acceptable weight of lift (MAWOL). Prediction models were determined for MAWOL based upon task, physiological and anthropometric variables as well as a combinations of these. The results indicated that MAWOL could be predicted fairly well.
    Perceived Exertion in Isometric Muscular Contractions Related to Age, Muscle, Force Level and Duration BIBA 712-716
      Joseph M. Deeb; Colin G. Drury
    This research was concerned with studying the development and growth of perceived effort of long-term isometric contractions as a function of muscle group (biceps vs quadriceps), of subjects with different age groups (20-29 vs. 50-59 years old) on long-term muscular isometric contractions (5 minutes) at different levels of {percent}MVC (20,40,60,80 and 100 {percent}MVC). An experiment testing 20 subjects each performing 10 conditions (two muscle groups x five levels of {percent}MVC) showed that the older age group reported Significantly higher perceived exertion at higher levels of {percent}MVC and across time. Furthermore, subjects experienced a higher and faster increase in their perceived exertion when the level of {percent}MVC and time increased.
    The Effects of Tool Type and Barrier on Time Required for a Remove and Replace Task BIBA 717-721
      David E. Kancler; Glen C. Robbins; William F. Moroney; David W. Biers
    The Air Force's CREW CHEF is a computer-graphics model of the physical characteristics of a maintenance technician. It is used to evaluate the ability of maintenance personnel to work in areas with respect to arm reach, operation of hand tools, strength available for torquing with wrenches, strength for manual materials handling, vision analysis, and accessibility analysis. A new CREW CHIEF feature under development is the Task Time Estimator, which will predict the time required to perform a remove/replace task in an obstructed environment. The goal of this experiment was to gather time to completion data and determine the effect of different tool type combinations.
       The task, performed while standing erect in a simulated work area, was to remove and replace a flange coupling while reaching through a six by eight inch opening. On half of the trials a barrier was positioned so as to restrict hand and tool movement. On the other half of the trials, no barrier was used. Thirty subjects, representative of USAF personnel, were divided into five groups, each of which utilized a different combination of wrenches (ratchet/box, box/box, box/open, open/box, and open/open).
       The ratchet/box and box/box tool combination resulted in the fastest completion times. The open/box combination resulted in intermediate completion times, while the box/open and open/open conditions produced the slowest completion times. Barrier presence increased the time required to complete both tasks and removal took less time than installation. Several noteworthy interactions and implications regarding tool selection are discussed.


    Applications of Optimization in Biomechanics: Consensus and Controversy BIBA 722-723
      Donald L. Fisher; Robert O. Andres; Bryan Buchholz; Richard Hughes; William S. Marras
    Increasingly, optimization is appearing as an integral part of biomechanical solutions to ergonomic problems. The primary objective of this panel is to introduce several different optimization tools and point out their related strengths and weaknesses.
       Optimization techniques have been used to solve a wide range of ergonomic problems. These problems include those which prove the most costly of the occupationally related disorders (in particular, lower back disorders) and those which are the most frequently reported of the occupationally related disorders (in particular, repetitive motion disorders). The problems addressed by this panel will include the above two disorders as well as several related ones. Specifically, mention will made of both lower back disorders (Marras) and repetitive motion disorders (Fisher) as well as slips and falls (Andres), mechanical trauma to the upper extremities (Buchholz), and more general problems requiring the determination of muscle forces (Hughes).
       The applications were also chosen to provide a window on the controversy which is attached to the use of various optimization techniques. Three elements of the controversy will be discussed: the verifiability of the ideal or optimal models of the biomechanical system; the tractability of the optimization techniques; and the generality of the optimization techniques.


    Biomechanical Analysis of Locomotion Patterns in Earth, Lunar, and Martian Gravity Environments BIBA 724-728
      Sudhakar L. Rajulu; Glenn K. Klute
    The primary objectives of this study were to determine the factors that affect stability during locomotion in both lunar and martian gravity environments and to determine the criteria needed to enhance stability and traction. This study tested the effects of three different speeds of locomotion and three different patterns of locomotion under three gravity conditions. The results showed some similarities across gravity levels with regard to changing the speed as well as the pattern of locomotion. Interestingly, the study also showed that as the gravity level decreased, the ratio of horizontal to vertical forces increased significantly. It appears that the tendency to move forward will be more in reduced gravity than compared to earth gravity. Thus, to ensure safe locomotion in reduced gravity, additional traction might be needed. Finally, selection of an appropriate traction material surface should be based on how well the ratio of horizontal to vertical forces is reduced.
    Effect of Product Structure on Manual Assembly Performance BIBA 729-732
      Girish V. Prabhu; Martin G. Helander; Valerie L. Shalin
    Using Maynard's description, an assembly task may be divided into various task elements like reach, select, grasp, move, position, and assemble (Ghosh and Helander, 1985). Activities such as "reach" and "move" are governed by biomechanics of body motions including human factors principles such as Fitts' law. This research investigated the effect of the structure of the assembly and the type of assembly instructions on performance. Two different product structures were used -- a vertical assembly, built bottom-up, and a hierarchical assembly, consisting of several sub-assemblies. Two different instruction strategies were used: 1. top-down sequential instructions 2. No Instructions. The research showed that vertical products were easier for manual assembly, when provided with instructions. For all three dependant measures, there was no interaction effect between the two factors, namely product structure and instructions. Average time for completion was significant for both factors i.e. product structures (F(1,20) = 4.417, p < 0.0485) and instructions (F(1,20) = 5.886, p < 0.0248). However, time for learning was significant only for product structure factor (F(1,20) = 5.239, p < 0.033). Also, trials to learn was significant only for product structure factor (F(1,20) = 4.449, p < 0.047).
    Heat Stress Associated with the Use of Tyvek Coveralls in Asbestos Removal Inspection BIBA 733-737
      Debra A. Griffith; William Reddan; William Schmitz
    This two-part study was undertaken to determine if increased heat stress was associated with the use of Tyvek suits at a given temperature and workload, and the effect of ambient temperature on the level of heat stress experienced within the suit.
       In the first part of the study the independent variables were: ambient condition (22.2° C and 50% rh vs. 32.2° C and 60% rh) and workload (20% vs. 40% of maximum VO2). The eight subjects ranged in age from 27 to 63, with equal numbers of men and women. Treadmill walking was used to simulate workload. Each experimental run lasted 45 minutes. In the second part, workload was fixed at 40% of maximum VO2 and the suits were not worn. All other conditions were the same. Subjects (female, age 32; male, age 32; male, age 63) were chosen from the original eight. Results for the two parts were compared.
       Wearing the suit increased the heat stress upon an individual. Rectal temperature increased by an average of .17° C, heart rate by 16 bpm, average heat stored by 54 kcals, and average sweat loss by .73 liters/m². Ambient temperature appeared to have a positive effect on the level of heat stress experienced within the suit. There were confounds, indicating a need for further study.
       It is recommended that ACGIH guidelines for work-rest ratio determination be followed, providing one adds 6°-11° C to the calculated ambient WBGT before entering the chart. These findings agree with the TLV WBGT Correction factors for clothing provided in the 1991 ACGIH guidelines on heat stress and the findings of Paull and Rosenthal (1987).
    Slip Distance as an Objective Criterion to Determine the Dominant Parameter between Static and Dynamic COFs BIBA 738-741
      Rohae Myung; James L. Smith; Tom B. Leamon
    Dynamic friction seems to be more appropriate as a measure of floor slipperiness. However, static friction has been more commonly used and has been a good measure for non-slippery conditions. Therefore, an experiment was conducted to find the dominant COF (static or dynamic) in non-slippery floors and correlating slip distance with each COF. As a result, slip distance was found to be a good measure to represent floor slipperiness because it was exponentially related with static and dynamic COFs. In conclusion, static COF can be a good parameter in non-slippery conditions for prevention of slips and falls.

    INDUSTRIAL ERGONOMICS: Back/Trunk Ergonomics

    The Effects of Lifting Posture on Trunk Muscle Activity BIBA 742-746
      Christopher A. Hamrick; Sean Gallagher
    Trunk muscle activity of twelve healthy males with coal mining experience was examined while each subject lifted a box under various conditions. The independent variables were four levels of posture (kneeling, stooped under a 1.2 m roof, stooped under a 1.6 m roof, and standing), height to which the box was lifted (35 cm or 70 cm), and weight of the lifting box (15 kg, 20 kg, or 25 kg). The dependent variables were the peak EMG values recorded during a lift for each of eight trunk muscles (left and right erectores spinae, left and right latissimus dorsi, left and right external oblique, and left and right rectus abdominis). Posture and weight of lift significantly affected peak activity of the left and right erectores spinae, the left and right latissimus dorsi muscles, and the right external oblique muscle. The latissimus dorsi muscle activity was highest in the low stooping posture, and was lowest in the kneeling posture, while erectores spinae activity was highest in the kneeling posture and decreased as the trunk became more flexed. Thus, the muscle activity during lifting tasks is affected by restricting a worker's posture. Consequently, many lifting guidelines and recommendations currently, in use may not be directly applicable to work being performed in restricted postures.
    Modeling the Stochastic Nature of Trunk Muscle Forces BIBA 747-751
      Gary A. Mirka; William S. Marras
    In an effort to understand the mechanism of low back disorders, researchers have developed EMG driven biomechanical models which estimate the magnitude of the internal reaction forces of the spine (compression and shear), by using information about the activity of the muscles of the trunk. But, because the trunk is multi-dimensional in nature, there is variability in the relative contribution of the various muscles, which implies variability in the reaction forces of the spine. Therefore, it may be more appropriate to discuss the range of spine reaction forces during a lift as opposed to the mean spine reaction force. The present research was an attempt to model the muscle forces stochastically and to develop a simulation model which predicts trunk muscle EMG that could occur during a lift. The simulated EMGs which resulted were then input into an EMG driven biomechanical model so the variability in spine reaction forces could be quantified. Under simple sagittally symmetric isometric conditions, compression which occurred at three standard deviations above the mean was 12% higher than that of the mean. The results for anterior shear (24% higher) and lateral shear (50% higher) showed even larger increases.
    Trunk Muscle Activation while Resisting Asymmetrically Applied Loads in an Axially Rotated Posture BIBA 752-756
      Steven A. Lavender; Yang-Hwei Tsuang; Gunnar B. J. Andersson
    The present investigation describes the electromyographic (EMG) response of eight trunk muscles during the application of loads to the torso while subjects maintained a twisted posture. The external moments of 20 and 40 Nm were applied to a harness system as each of the 10 subjects twisted 25 degrees. The applied moment direction was varied in 30 degree increments completely around the subjects (0 to 330 degrees). Surface EMG was used to monitor the left and right Latissimus Dorsi, Erector Spinae, External Oblique, and Rectus Abdominus. Multivariate and univariate analyses of variance (MANOVA and ANOVA) procedures showed significant main effects for all muscles and a significant moment magnitude by moment direction interaction effect in 6 of the 8 muscles. The greatest muscle activity was observed in the right Erector Spinae and the left External Oblique muscles. The results are also compared with an earlier study in which a similar loading paradigm was used as subject maintained a neutral upright posture.
    Industrial Quantification of Occupationally-Related Low Back Disorder Risk Factors BIBA 757-760
      William S. Marras; Steven A. Lavender; Sue E. Leurgans; Sudhakar L. Rajulu; W. Gary Allread; Fadi A. Fathallah; Sue A. Ferguson
    Few assessment techniques have attempted to define the role of occupational trunk motion in the risk of occupationally-related low back disorder (LBD) even though laboratory studles have indicated that motion significantly increases spine loading. An in-vivo study was performed to assess the contribution of three-dimensional dynamic trunk motions to the risk of LBD during occupational lifting in industry. Over 400 industrial lifting jobs were studied in 48 industries. Specific manual materials handling jobs historically identify as either high risk or low risk for LBD were identified. A tri-axial electrogoniometer was worn by workers and documented the three-dimensional trunk motion characteristics associated with these high risk or low risk jobs. Workplace characteristics such as load moment arm, load weight, etc. were also documented for each of the repetitive lifting tasks. A multiple logistic regression model indicated that a combination of five trunk motion and workplace factors (lifting frequency, load moment, trunk lateral velocity, trunk twisting velocity, and trunk sagittal angle) predicted occupational-related LBD risk well. The analyses have enabled us to determine the LBD risk associated with combined changes in the magnitudes of the five factors. This model could be used as a quantitative, objective measure to redesign the workplace so that the risk of occupationally-related LBD is minimized.


    Effects of Mass on Wrist Velocities and Accelerations BIBA 761-764
      Jasper Shealy; Wendi Latko
    Upper Extremity Cumulative Trauma Disorders (UECTD) have been linked to risk factors such as frequency, forcefulness, posture and time for rest/recovery. More recently, wrist and forearm movement velocities and accelerations have been identified as significant correlates to UECTD in industrial tasks. In earlier work with biomechanical analysis of Sign Language Interpreting (SLI), we found that SLI involves frequencies, velocities and accelerations of wrist and forearm motions that greatly exceed those noted as UECTD high risk jobs. A primary difference between the workers in the industrial studies and our studies of SLI is that industrial workers typically hold objects in their hands, while in SLI, the hand is empty. In SLI, we have found the maximum velocities and accelerations reach as much as 70 to 80% of the maximum possible values.
       This study looks at the effect of holding graduated masses on the maximum velocities and accelerations for the wrist joint for the flexion/extension and radial/ulnar deviation and forearm pronation/supination motions. Five subjects were used. Each subject repeated a maximum voluntary motion three times in each configuration, starting from a stationary neutral position, with the forearm held stationary for the wrist movements. Four different masses were used (9.5, 125, 250 and 500 grams) to assess the effect of mass. Each mass was a cylinder of the same external dimensions. As a control, a hollow cardboard tube (9.5 grams) was used to measure the velocity and acceleration for essentially a no-load condition. Thus the hand was always in the same grip configuration.
       The results show that for the masses and hand-grip configurations used, the effect of the masses was not statistically significant for forearm pronation/supination, but was for wrist movements. The effect was greatest for flexion/extension, with about a 20% decline in velocity and acceleration at 500 grams versus the 9.5 gram weight.
    Effects of Hand Vibration on Postural Stability BIBA 765-769
      Lisa Fletcher; Hee-Seok Park; Bernard J. Martin
    The present work was aimed at defining the contribution of vibration-induced perturbation of hand proprioceptive/exteroceptive feedback on standing equilibrium. A vibrating handle, free in space or fixed to a stationary support, was held in the dominant hand while maintaining an erect posture on a force platform, eyes closed. Four arm positions were used. The results show that body sways increase significantly during hand vibration exposure when the handle is fixed. Significant shifts of the center of pressure COP are elicited in every situations. Furthermore, the shifts of the COP are clearly oriented in the direction of the handle when this latter is fixed. It is suggested that the proprioceptive information issued from the hand contributes to the elaboration of a spatial reference and to the control of posture as a function of the environmental context. These results indicate that hand vibration exposure can be considered as a risk factor which may contribute to fall accidents.
    Comparison of Power Grasp and Three-Jaw Chuck Pinch Static Strength and Endurance between Industrial Workers and College Students: A Pilot Study BIBA 770-774
      Dianne L. McMullin; M. Susan Hallbeck
    Due to the ease of obtaining subjects, much ergonomics research utilizes students. However, is it valid to make a hypothesis concerning industrial workers from this student data? To evaluate the validity of such a generalization, ten industrial workers and ten students, five men and five women from each subject sample participated in the study. The functional range of motion for extension and flexion in the wrist and anthropometric measurements of the hand and arm were measured for each subject. In addition, the three-jaw chuck pinch force and endurance and power grasp force and endurance were also measured. The data was analyzed using both paired comparisons and ANOVA tests. Only power grasp force showed a strength difference between students and industrial workers. The students had 82.9% of the grasp force of the industrial workers.
    Development of a New Automated Tactility Test for Assessing Hand Sensory Function BIBA 775-778
      Robert G. Radwin; One-Jang Jeng; Edward T. Gisske; Young-Lae Park
    Design and test results of an automated aesthesiometer for measuring gap detection threshold in a tactile inspection task are presented. What distinguishes this test from conventional tactility tests, such as two-point discrimination or monofilaments, is that it measures performance in a functional tactility task resembling those performed during manual work activities. Although test conditions are highly controlled, this test still permits natural finger probing activity while sensing surface feature defects like scratches, rather than sensing static unnatural sensory stimuli such as distinguishing two points, or detecting a point-pressure stimulus. The size of a precision scratch, or gap, introduced in an otherwise smooth surface is controlled using a micropositioner capable of producing a gap as small as 0.1 µm. Finger contact force is also carefully controlled within 100 mg accuracy for loads between 25 g and 75 g using a precision balance beam system. This instrument is entirely under microcomputer control and can be administered on a table-top in the field. In this study, normative performance is compared between static and dynamic sensory function rapid method of limits threshold detection paradigm. Probability of detecting randomly presented stimuli was also studied.


    Ergonomics Research Efforts in the Supermarket Industry BIBA 779-782
      Thomas J. Sluchak; Mark S. Hoffman; David J. Cochran; William S. Marras; Katharyn Grant; Daniel Habes
    This panel is composed of researchers from private industry, academia and NIOSH, who are currently involved with ergonomics research in the supermarket industry. Presenters summarize their research efforts and discuss key ergonomics challenges present in the supermarket industry today.


    Application of Survival Analysis to CTD Risk Assessment BIBA 783-787
      Donghyun Park
    This paper demonstrates the application of survival models to CTD (Cumulative Trauma Disorder) studies. Survival analysis techniques are usually applied to the analysis of prospective epidemiological studies examining related risk factors. However, survival models have never been used in CTD etiology, perhaps due to mathematical complexities imposed on survival analysis techniques and its interpretation. The other reason might be the fact that it has not been considered as serious as other diseases usually studied in epidemiology. However, the conditions and assumptions of survival models fit completely into CTD studies (the existence of concomitant variables, a heterogeneous study population, censored observations etc.). Thus it is inappropriate to analyze CTD problems (specifically etiology and prevention) using typical statistical technique (ANOVA or ordinary regression).
       In this study, 143 subjects participated from an automobile carpet manufacturing plant which was experiencing a high number of CTD cases (107 cases, 1988-1989) and two groups of potential risk factors were examined. They were mainly categorized into personal and job-related information. This information was collected through survey questionnaires and video-taping. As the first step of analysis, survival, hazard and probability density functions were estimated. The estimated survival function shows that CTD incidence rate remained relatively constant fluctuating 5-15%, through the first 12 years. Also, univariate associations between survival time and individual risk factors were tested using log rank and Wilcoxon rank test. Finally, the CTD data was fitted to 'Proportional Hazard Model' (the most generalized survival model with distribution-free baseline hazard function). This model explains 75% (R²=0.75) of CTD data with the following covariates; cycle time per part, number of meals a day, dominant hand, general attitude, hand posture, degree of physical fitness, hobby and job title. The feasibility of the Proportional Hazard Modeling was investigated by test and plot. The test was conducted under the global null hypothesis about the significance of the overall model and t vs. log(-log(S(t))) was plotted to check with the assumption of proportionality. Both results ascertain the feasibility of Proportional Hazard Modeling for CTD studies.
    Carpal Tunnel Syndrome Prevalence in a Heavy Railroad Maintenance and Repair Facility BIBA 788-790
      T. L. Stentz; M. W. Riley; C. L. Glismann; J. L. Ballard; R. C. Sposato
    Carpal tunnel syndrome (CTS) is clinically evaluated with the aid of nerve conduction testing. CTS diagnosis is typically confirmed by the presence of higher than normal median nerve distal latencies accompanied by lower than normal conduction velocities depending on the degree of neuropathy. The main objective of this research was to estimate the prevalence of CTS in a population of 800 railroad maintenance workers. A non-random sample of 322 volunteer workers participated in the study. Demographic and anthropometric data was collected. Median nerve distal latencies and conduction velocities were measured on both hands. Based on the test results, subjects were separated into 6 classes of CTS severity from "normal" to "severe". Data analysis revealed some CTS was present. Analysis of wrist geometry did not confirm wrist squareness as a predictor of CTS.
    Grip Strength as a Function of Forearm Rotation and Elbow Posture BIBA 791-795
      Robert J. Marley; Rob R. Wehrman
    An investigation was performed to assess the effect of forearm rotation (pronation and supination) and elbow orientation upon maximum grip strength of 10 male and 10 female subjects. Seven positions of forearm rotation which ranged from 90 degrees pronation to 90 degrees supination in both the 90 degree elbow flexion (arm adducted, forearm horizontal) and 0 degree flexion (shoulder flexed, whole-arm extended forward and horizontal) postures were examined. Thus a total combination of 14 postures were documented. Results indicate that maximum grip strength decreased significantly with forearm pronation, relative to the "neutral" forearm posture (p = 0.086). Other rotation postures did not yield significantly different grip strength from the neutral, but there was a clear decreasing trend in grip strength with forearm rotation away from neutral, particularly in pronation. The 0 degree elbow flexion showed the highest average grip strength values compared to 90 degree elbow flexion postures. Also, in the 90 degree elbow flexion posture, grip strength tended to increase with some supination from neutral rotation. It is recommended that for repetitive grasping activities, the arm and forearm postures should be considered in evaluating maximum grip strength. A regression model is presented to estimate maximum grip strength as a function of forearm rotation and elbow posture.
    Effects of Full-Motion Forearm Supports and a Negative Slope Keyboard Support System on Hand-Wrist Posture while Keyboarding BIBA 796-800
      James R. Powers; Alan Hedge; Michael G. Martin
    The effects of full motion forearm supports and a negative slope keyboard support system on hand-wrist posture was tested. No differences in posture were found between normal use of a keyboard and that with full motion forearm supports. Use of the negative slop keyboard support system increased body-to-screen distance and reduced wrist extension so that the wrist was vertically neutral for keyboarding.


    The Effects of Forearm Posture, Wrist Posture, Gender, and Hand on Three Peak Pinch Force Types BIBA 801-805
      M. Susan Hallbeck; Abe H. Kamal; Paul E. Harmon
    In many industries the hand is utilized as a fixture, pinching in various wrist postures and forearm postures. In an effort to quantify the effects of wrist posture, forearm posture, gender, and dominant/non-dominant hand upon three peak pinch forces, a study was performed. Three pinch types were tested in this study: index pad pinch, middle pad pinch, and three-jaw chuck pinch force. For each pinch exertion condition, one of five wrist postures were employed: neutral, 45° extension, 65° extension, 45° flexion, and 65° flexion. Each pinch was also performed in one of three forearm postures: neutral, full pronation, and full supination. Ten subjects between 20-25 years of age within each gender category were tested giving a total of 20 subjects. Each subject was asked to build up to his or her maximal voluntary contraction using a modified Caldwell regimen, and hold that pinch level for three seconds. Results were analyzed using analysis of variance (ANOVA) with significant effects (gender, hand, pinch type, wrist posture, and forearm posture) tested using post hoc analysis. The results and their implications are discussed.
    Using Force-Sensitive Resistors to Evaluate Hand Tool Grip Design BIBA 806-810
      Myung Hwan Yun; Kentaro Kotani; Darin Ellis
    The pressure distribution of the hand is an important element in evaluating hand tool grip. For measuring the pressure distributions of the hand, a portable sensor glove was developed using force sensitive resistors of the conductive polymer type. Pressure distributions of three hand tools for three male subjects were measured. The pressure distribution pattern varied significantly between type of grip, location, and subjective exertion level. Factor analysis was used to identify the relative importance of each area of the hand doing grip action. The results showed that there is an 'active' area involved in gripping the hand tool and a 'control' area which supports the hand motion for the given task. Studies about hand tool pressure distributions will provide an important guideline in designing a new tool or improving an existing one. A microcomputer based system is being developed that records data on grip pressure distribution throughout a tool grip task. The digitized data then will be analyzed both graphically and statistically and will be used to evaluate various hand tools for industrial settings.
    Shape and Placement of Faucet Handles for the Elderly BIBA 811-815
      Beverly A. Meindl; Andris Freivalds
    The 'modern' bathroom is an area which poses considerable barriers to the elderly, specifically a mismatch between the shape and the placement of faucet handles and their physiological capabilities. Fifteen residents of a retirement facility, with a mean age of 79.9 years, exerted their maximum turning torques in a randomized fully-crossed design incorporating the following factors: two positions (low-21 inches and high-42 inches), two angles (45° and 90°) and three types of handles (acrylic, star, and lever). Analysis of covariance (ANCOVA) of the data indicated that the type of handle and the position, along with the covariates: age, gender and subject height, were significant at p<.05. Angle and the covariates: weight and arthritis were not significant, most likely because weight is correlated with height and arthritis with age. The second order interactions of handle-angle and position-angle were also significant at p<.05.
       The lever handle was clearly superior with average torques produced being 50% greater than those from the acrylic and star handles. Torque levels on the acrylic handle and the star handle were very similar, with the acrylic handle slightly superior in the 45°-angled position and the star handle being slightly better in the 90°-angled position. Overall, the 45°-low position resulted in the lowest torques, while the 45° high position resulted in the highest torques. Age had a profound effect, with torque values decreasing an average of 10% over the 15 year age span of the subjects. Based on the study, it is recommended that plumbing systems with both high (42 inches) and low (21 inches) faucets with lever handles be installed where ever possible.
    Force Distribution at Hand/Handle Coupling: The Effect of Handle Type BIBA 816-820
      R. R. Bishu; Wang Wei; M. S. Hallbeck; D. J. Cochran
    Handle location and geometry play an important role in container design and effectiveness. An ideal handle position and angle should minimize stress at L5/S1 and minimize average grip pressure on the two hands with force distributed evenly on both hands. Handles in such a position will be most comfortable for performing a MMH task and reduce the likelihood of compressive injuries on the lumbar spine. Most of the published research on container handles have used the psychophysical, biomechanical, and/or physiological methods to determine handle effectiveness. The force distribution at the exact point of energy transfer, namely the hand/handle interface has rarely been addressed by the scientific community. The intent of this study was to determine the force distribution at the hand/handle interface and use the same to compare the effectiveness of various handle types, positions, and angles. Six factors were tested in this experiment using a fractional factorial design. The pressure at the interface was measured using a number of force sensing resistors (FSRs) in each hand. The results indicate handle positions 2/2, 8/8, and 3/7 to be far superior to position 6/8. The average pressure at the FSR sites appear to be the least at handle angles of 0 degree. Further, the force distribution for the cut-out handle appears to be more uniform than that for the cylindrical handle (circular cross-section). Based on these findings recommendations are made for container designer.