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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 and Ergonomics Society 38th Annual Meeting 1994-10-24

Fullname:Proceedings of the Human Factors and Ergonomics Society 38th Annual Meeting
Note:People and Technology in Harmony
Location:Nashville, Tennessee
Dates:1994-Oct-24 to 1994-Oct-28
Standard No:ISSN 0163-5182; TA 166 H794; hcibib: HFS94-1
Links:Online Proceedings
  1. HFS 1994-10-24 Volume 1
    2. AEROSPACE SYSTEMS: Display Development [Lecture]
    3. AEROSPACE SYSTEMS: Pilot Information Processing [Lecture]
    5. AEROSPACE SYSTEMS: Environmental Factors Influencing Performance [Lecture]
    6. AEROSPACE SYSTEMS: Issues in Air Traffic Control [Lecture]
    7. AEROSPACE SYSTEMS: Evaluation Metrics and Inexpensive Simulation [Lecture]
    8. AEROSPACE SYSTEMS: Human Factors and Ergonomics in Maintenance and Inspection [Symposium]
    9. AEROSPACE SYSTEMS: Aerospace Issues [Lecture]
    10. AGING: Designing for an Aging Population [Lecture]
    11. AGING: Panel
    12. AGING: Aging and Information Processing [Lecture]
    13. COMMUNICATIONS: Hands-On Answers on Personal Digital Assistants: Part II [Symposium]
    14. COMMUNICATIONS: Design Issues in Telecommunications [Lecture]
    16. COMPUTER SYSTEMS: Analysis and Modeling of Use of Procedures in Dynamic Worlds: Implications for the Design of Computer-Based Procedures [Symposium]
    17. COMPUTER SYSTEMS: Developing Supporting and Cooperative Systems [Lecture]
    19. COMPUTER SYSTEMS: Visual Perception in Virtual Environments [Lecture]
    20. COMPUTER SYSTEMS: User Interface Navigation and a Model for Explicit Research-Practice Interaction [Symposium]
    21. COMPUTER SYSTEMS: Virtual Reality and Virtual Environments [Lecture]
    22. COMPUTER SYSTEMS: User Interface Design Issues [Lecture]
    23. COMPUTER SYSTEMS: Integrating Human Factors within Software Engineering Practices [Symposium]
    24. COMPUTER SYSTEMS: Input Techniques [Lecture]
    25. COMPUTER SYSTEMS: Usability [Lecture]
    26. CONSUMER PRODUCTS: Alternative Format
    27. CONSUMER PRODUCTS: User Interface Design [Lecture]
    28. CONSUMER PRODUCTS: Labels and Warnings [Lecture]
    30. EDUCATORS' PROFESSIONAL: Issues in Training and Learning Human Factors [Lecture]
    33. ENVIRONMENTAL DESIGN: A Systems Approach to Preventing Work-Related Musculoskeletal Disorders in VDT Work [Symposium]
    35. FORENSICS PROFESSIONAL: Problems with User Information [Lecture]
    37. GENERAL SESSIONS: Issues in Automobile Transportation [Lecture]
    39. GENERAL SESSIONS: Report of the Technical Advisory Group [Symposium]
    40. GENERAL SESSIONS: Displays and Vision Potpourri [Lecture]
    41. GENERAL SESSIONS: General Sessions Potpourri [Lecture]
    42. GENERAL SESSIONS: Human Factors and Design Factors: Two Sides of the Same Coin? Part I [Symposium]
    44. INDUSTRIAL ERGONOMICS: Hand and Wrist Ergonomics I [Lecture]
    45. INDUSTRIAL ERGONOMICS: Lifting and Carrying [Lecture]
    46. INDUSTRIAL ERGONOMICS: Ergonomics in Space [Lecture]
    47. INDUSTRIAL ERGONOMICS: Hand and Wrist Ergonomics II [Lecture]
    48. INDUSTRIAL ERGONOMICS: Psychophysical Methods [Lecture]
    50. INDUSTRIAL ERGONOMICS: Lifting [Lecture]
    52. INDUSTRIAL ERGONOMICS: Ergonomic Applications I [Lecture]
    53. INDUSTRIAL ERGONOMICS: Ergonomic Applications II [Lecture]

HFS 1994-10-24 Volume 1


A Look at the HFES Mission through the Years BIB --
  Deborah A. Boehm-Davis

AEROSPACE SYSTEMS: Display Development [Lecture]

The Use of Aiding Techniques and Varying Depth Volumes to Designate Targets in 3-D Space BIBA 1-5
  Thomas J., Jr. Solz; John M. Reising; Kristen K. Liggett; Troy Lohmeyer; David C. Hartsock
The purpose of this study was to determine the effectiveness of a hand tracker to designate targets using a three-dimensional (3-D) map. Three variables were manipulated: 1) hand tracker active volume, 2) aiding technique, and 3) target density. There were three different volumes (large, medium and small) in which the hand tracker operated. Each volume represented cockpit space in which hand tracker movements correlated to cursor movements on the screen. Two aiding techniques were referred to as contact aiding and proximity aiding. Contact aiding consisted of a color shade change to the target when the cursor penetrated the target volume. Proximity aiding consisted of an algorithm that selected the target closest to the cursor and thus changed its color shade. Two target densities, high (16 targets) and low (8 targets), were used. Speed and accuracy were measured in the designation of targets using a hand tracker. Results showed that proximity aiding in the medium volume space yielded the best performance.
Conformal Symbology, Attention Shifts, and the Head-Up Display BIBA 6-10
  Christopher D. Wickens; Jeffry Long
Thirty-two pilots flew instrument approaches in a high-fidelity simulator. Location of flight symbology was manipulated head-up vs. head-down while controlling for optical distance and symbology format. Pilots were assigned to one of two symbology sets, conformal and non-conformal. Each pilot flew half of the trials with the symbology presented in a head-up location and half with the symbology located head-down. Airspeed tracking for both groups was displayed with non-conformal digital symbology. An unexpected far domain event was presented on one trial per pilot. The results revealed that, for flight path control, there was generally a cost associated with head-down location. The magnitude of this cost was larger for conformal than for non-conformal symbology. Head-up presentation resulted in faster transition from instrument to visual flight reference, but poorer airspeed tracking and slower response to the far domain unexpected event and greater error tracking digital airspeed. The results are interpreted with the theoretical framework of object-based and space-based theories of visual attention, and the tradeoffs between clutter of overlapping imagery and information access cost.
Expanding the Envelope of Performance: Training Pilots to Use Helmet Mounted Displays BIBA 11-15
  F. Jacob Seagull; Daniel Gopher
Helmet Mounted flight Displays (HMDs) of a through-the-window field-of-view (FOV) are widely used in modern aircraft for night vision. Unfortunately, pilots using such displays are susceptible to spatial disorientation due to the limited field-of-view and its consequent lack of orientation cues. This problem is especially pronounced when pilots move their heads, though this is precisely the behavior that enables them to counteract the limited FOV. The current experiment attempted to train pilots to move their heads without becoming disoriented. Twenty-five subjects participated in five treatment groups in a between-subjects design. Subjects piloted a simulated helicopter through a computer-generated winding canyon with either a single-eye HMD, or a binocular through-the-window "screen" display. Three control groups were trained using either (1) a binocular screen-display without a secondary task, (2) an HMD view without a secondary task, or (3) an HMD view with a secondary task presented in the center of the HMD FOV. The two remaining treatment conditions involved flying while carrying out a secondary task which required either (1) systematic head movement (displacement), or (2) systematic head-movement plus head re-orientation. Results indicate that after training, treatment groups completed significantly more flights without crashing using the HMD than did the control groups. They also had a significantly higher probability of surviving a given flight at any time. Treatment groups learned to increase their head movement, while control groups spontaneously reduced theirs. These findings indicate that spontaneous experience with an HMD does not lead to optimal performance. Development of attention control strategies focusing on the difficulties of HMDs increased considerably the ability of operators to cope with the problems.
Egocentric and Exocentric Displays for Terminal Area Navigation BIBA 16-20
  Christopher D. Wickens; Chia-Chin Liang; Tyler Prevett; Oscar Olmos
Two experiments are reported that contrast egocentric vs. exocentric features of perspective (3D) or plan view (2D) electronic map displays for supporting local guidance and global awareness. Pilots used these displays for a simulated approach to a landing along a curved approach, through a terrain-filled region. The task was simulated on an IRIS visual graphics workstation. In Experiment 1, a rotating vs. fixed-map display was experimentally crossed with a 2D vs. 3D (perspective map) view as 24 pilots were assessed in their ability to maintain the flight path (local guidance) and demonstrate global awareness of surrounding terrain features. Rotating displays supported better flight path guidance in both the lateral and vertical axes, and did not substantially harm performance on the task of recalling the location of terrain features. Map rotation also supported better performance in locating features from an ego-referenced but not a world-referenced perspective. 3D displays provided a slight advantage for lateral guidance but a substantial cost for vertical control, because of the ambiguity with which perspective viewing depicted precise altitude. In Experiment 2, 10 pilots flew with the rotating 2D display, and with an improved version of the rotating 3D display, using color coding to reduce the ambiguity of altitude information. Vertical control improved as a result of the 3D display design improvement, but lateral control did not. Assessment of terrain awareness on a map reconstruction task revealed marginally better performance with the 2D map. The results are discussed in terms of the costs and benefits of presenting information in 3D, ego-referenced format for both local guidance and global awareness tasks.

AEROSPACE SYSTEMS: Pilot Information Processing [Lecture]

Actions Speak Louder Than Words: How Pilots Use Nonverbal Information for Crew Communications BIBA 21-25
  Leon D. Segal
How does the design of an aircraft cockpit affect crew communication? The research described hereunder aimed at identifying aspects of design that play a critical role in task coordination, yet have heretofore been ignored. It is proposed that crewmembers coordinate the performance of tasks using visual, nonverbal, information that emerges from the interactions between individual pilots and the aircraft's systems. 24 airline pilots participated in a high-fidelity simulator experiment which compared the impact of three different types of interface on crew communication and coordination. Measurement included detailed video recording, and quantitative and expert performance evaluations. The data suggest that pilots visually monitor each other's performance of tasks, that visual monitoring is affected by the design of the interface, and that pilots rely on such nonverbal information for communication and coordination. The discussion looks at implications of these data to the design of workstations and cockpits.
Keeping in Touch: Kinesthetic-Tactile Information and Fly-by-Wire BIBA 26-30
  R. J. B. Hutton; J. M. Flach; B. J. Brickman; C. O. Dominguez; L. Hettinger; M. Haas; C. Russell
Fly-by-wire control systems in advanced cockpits provide an opportunity to simplify the manual control demands on the pilot. However, this simplification may be at the expense of distancing the pilot from direct contact with important sources of information. Control loading systems provide the opportunity for enhancing the capacity of the stick as an information channel, providing the pilot with information about the critical aircraft state variables required for control. In this study parameters governing the movement of the pilot's control stick (i.e. the stiffness of a spring-centered stick) were dynamically adjusted to be proportional to moment-to-moment states of the simulated vehicle (i.e. roll velocity). The hypothesis was that the "feel" of the dynamically varying stick would provide control information leading to more precise control performance in a single-axis roll tracking task. RMS error results did not support this hypothesis. The result is discussed in the context of an ongoing research program to examine strategies for information integration in advanced cockpits.
Attentional Control and Piloting Experience BIBA 31-35
  Mingpo Tham; Arthur Kramer
The present study investigated differences in attentional abilities between student and instructor pilots. Twenty-four student and thirty-one instructor pilots were administered a battery of attention tasks in an effort to determine whether attentional abilities would co-vary with the level of piloting experience. The tasks that the pilots performed included: the response compatibility task, the negative priming task, the inhibition of return task, a timesharing task, feature and conjunction visual search tasks, and the dichotic listening task. Instructor pilots displayed evidence of more efficient task switching, and focused attention than novice pilots. On the other hand, instructors and student pilots were equally facile at visual scanning and covert shifts of spatial attention. The results of the study suggest that novice and experienced pilots differ across a variety of attentional operations.
Instrument Scan and Pilot Expertise BIBA 36-40
  Arthur Kramer; Mingpo Tham; Christopher Konrad; Christopher Wickens; Gavan Lintern; Roger Marsh; Julianne Fox; David Merwin
A study was performed to investigate the correspondence between flight experience and instrument scan strategies. Seventeen student and twenty one instructor pilots flew two instrument flight missions with each mission being composed of eight distinct flight segments. The segments varied in the number of flight parameters that were to be modified including changes in heading, airspeed and altitude as well as double and triple combinations of changes in these parameters. All of the flight segments were flown under strict time constraints. Discriminant analyses were employed to determine the extent to which performance, control and eye scan measures could be used to distinguish among three groups of pilots; student pilots, low time instructors, and high time flight instructors. Performance measures alone were not adequate for discriminating among these groups of pilots, possibly because the maneuvers were relatively simple to fly. However, when both performance measures and eye scan measures were employed discrimination accuracies improved dramatically, ranging from 77% to 98% in the more complex maneuvers. Eye scan measures were also useful in diagnosing deficiencies in student flight strategies such as the over-reliance on a subset of flight instruments.


Unrecognized Training Needs for Airline Pilots BIBA 41-45
  Robert O. Besco; Dan Maurino; Martin H. Potter; Barry Strauch; Richard B. Stone; Earl Wiener
The following issues are covered. All of these are currently judged, by at least one of the authors, to be under emphasized or even unrecognized in current airline training practices or Federal Aviation Administration (FAA) training requirements.
  • 1.) Introducing computer naive pilots to automated aircraft and bringing pilots
        up to a nominal level of computer literacy;
  • 2.) Identifying what existing knowledge, skills, and attitudes need refresher
        training and the frequency with which to retrain;
  • 3.) Decision making in automated aircraft;
  • 4.) Imbedded flight management system training;
  • 5.) Reality and proficiency maintenance training for inexperienced extra crew
        members on long haul operations:
  • 6.) Analysis and coding techniques for anomalies encountered at liftoff;
  • 7.) Low altitude, low speed handling qualities and stall recoveries;
  • 8.) Communication skills and standardized terminology sets for inquiry,
        challenge, and intervention by subordinate crew members;
  • 9.) Use of decision trees for legality decisions in takeoff and landing;
  • 10.) Conflict and ambiguity resolution training to identify organizational and
       system induced goal conflicts.
  • 11.) Coping with real-time mission changes, software incompatibilities, and
       anomalies in automated aircraft.
  • 12.) Abort decision making.
  • AEROSPACE SYSTEMS: Environmental Factors Influencing Performance [Lecture]

    Cumulative Effects of +Gz on Cognitive Performance BIBA 46-50
      Jeffrey G. Morrison; Estrella Forster; Edward M. Hitchcock; Charles A. Barba; Thomas P. Santarelli; Mark W. Scerbo
    A study is described which examines the interaction of two of the most salient stressors found in the tactical aviation cockpit: 1) highly demanding decision-making tasks, and 2) intermittent periods of high G. Addressing this issue is critical because: 1) it is probable that physiological stressors such as G may have serious ramifications on pilots' abilities to perform complex cognitive tasks; 2) there may be different impacts of G on different types of cognitive tasks, and the impact of these deficits may be correlated with the cumulative amount of time a pilot has spent under G.; 3) it is not clear that donning protective gear will have an effect on cognitive task performance; and 4) there are no data to suggest how long cognitive decrements due to exposure to physiological stressors will last. A general approach is described for evaluating the cumulative effects of physiological stressors (e.g., G) on cognitive task performance in a within-subjects experimental design. A PC-based task suite was used incorporating three concurrently performed tasks: a compensatory tracking task, a resource management task, and a system monitoring task. Results indicated that performance across the experimental conditions was highly variable. Preliminary results demonstrated that: 1) even low-level increases in G can be disruptive to subject performance, 2) there are cumulative decrements in task performance during G, and 3) if stable performance on tasks is required, training for complex task performance must take place in the presence of salient physiological stressors.
    A Study of the Effects of Repeated 36-Hour Simulated Missions on B-1B Aircrew Members BIBA 51-55
      Kelly J. Neville; Roger U. Bisson; Jonathan French; Johnnie Martinez; William F. Storm
    The military goal of Global Reach - Global Power entails an unprecedented dependence on immediate and sustained long range bombing campaigns. This research effort was initiated to evaluate the feasibility of this type of long range operation by studying the effects of multiple long duration missions on bomber aircrews. Measures of cognitive performance, mood, fatigue, and sleep management suggest that crews learned to adapt to the missions. However, cognitive performance deteriorated during the early morning hours of each mission and expert ratings of flight deck performance suggest that some components of performance may have been negatively impacted by the repeated missions. This research contributes to the base of information that may be used to make operational risk decisions and suggests ways to reduce schedule-related risks. It also explores the effects of sustained operations on complex tasks, as well as on simple tasks, and explores the use of multiple data collection techniques in a non-laboratory setting.
    Concepts for Improving the Flight Crews Work Environment within the ESA's Attached Lab BIBA 56-60
      Jim Muccio; Edward Gibson; Wubbo Ockels; Michelle Allen
    Man's presence in space has proved to be an extremely valuable asset. During the past thirty years of manned space flight there have been numerous instances where man's ingenuity, fortitude, ability to deal with the unexpected, weigh risks, anticipate potential problems, and propose potential solutions have been largely responsible for the success of the mission. Nevertheless, the value of man in space is limited; for it is largely determined by how much he can produce; his productivity, in turn, is determined not only by the intrinsic abilities that he brings to the job, but also by the work environment provided him. In short, it is the intent of this paper to discuss some of the concepts and recommendations under consideration by the Columbus Program's Crew Activities Office for improving the productivity of the flight crews' work environment; where gains in productivity are defined in terms of increased crew efficiency, decreased crew error, and decreased crew training requirements. In doing so, this paper will address such areas as the flight crews' activity planning, their workstation design, and their on-board training. This paper will draw heavily from past space experiences, from Skylab, Shuttle Spacelab, and Solyut missions. The concepts and recommendations proposed are the result of: (1) direct hands-on experience from former NASA, ESA, and Russian astronauts; (2) a time and motion study of a past Spacelab mission (performed to better understand where and how crews spend their time); or (3) multiple crew workstation and neutral buoyancy simulations.
    Contextual Elements and Human Factors Impacting Human Performance for Long-Duration Space Flight BIB --
      Dwight A. Holland

    AEROSPACE SYSTEMS: Issues in Air Traffic Control [Lecture]

    The Implications of Data-Link for Representing Pilot Request Information on 2D and 3D Air Traffic Control Displays BIBA 61-65
      Christopher D. Wickens; Sonia Miller; Mingpo Tham
    Twenty-four subjects (seven ATC specialists and 17 pilots trained in fundamental ATC skills), performed a simulation in which they were required to evaluate pilot requests for flight plan changes, issued by aircraft depicted on their display. Some requests could be safely granted, whereas others would bring about a mid-air conflict with other aircraft. Subjects evaluated the requests in the context of an airspace depicted on either a conventional 2D planar display or a 3D perspective display. Requests were presented either as voice messages or were displayed visually, as if relayed via data-link, either printed at the bottom of the display or represented as vectors, emanating in the requested direction from the requesting aircraft. The results indicated that performance was generally equivalent with the 2D and the 3D display and was best with the auditory-verbal request mode. It was considerably slower with the print mode, presumably because of the greater scanning required. The spatial vector mode offered performance that was faster than print, but considerably less accurate. Particular deficiencies were noticed with the vector mode when it was used to present complex 3-dimensional requests in the context of the 3-dimensional display.
    A Simulator Study of the Effect of Information Load and DataLink on Crew Error BIBA 66-70
      Dennis G. Hrebec; Susan E. Infield; Susan Rhodes; Fred E. Fiedler
    This study investigated the effects of air traffic control (ATC) induced information load and ATC communication modality on crew error in a fixed-base Boeing 747-400 flight deck simulator. To accomplish this, data from an experiment conducted by Boeing (Logan, et al., 1992) were re-analyzed. In this experiment, flightcrews engaged in two high-fidelity, full-mission scenarios. For this reanalysis, the variability in the amount of information ATC transmitted to the crew in the scheduled clearances was examined as an independent variable. To quantify this measure of information load, each scheduled ATC clearance was decomposed into mutually exclusive informational units called propositions. Each proposition consisted of one discrete "chunk" of information. On average, ATC clearances in the high information load condition contained more than two and a half times as many propositions as clearances in the low information load condition. Flightcrews made significantly more errors, and more errors per proposition, in the high information load condition than in the low information load condition. This indicates that it was the density of the information, or how many propositions were packed into each clearance, and not just the quantity of information which affected crew performance. Another manipulated variable was ATC communication modality. Each flightcrew participated in one scenario using a standard voice communications modality exclusively and in the other scenario using a combination of voice and digital DataLink. Though flightcrew error was significantly lower in the DataLink condition than the voice condition, this tendency was moderated by information load. In the low information load condition, flightcrews committed approximately the same number of errors in the voice and DataLink conditions, but in the high information load condition, flightcrews committed many more errors in the voice condition than the DataLink condition.
    Situation Awareness Information Requirements Analysis for En Route Air Traffic Control BIBA 71-75
      Mica R. Endsley; Mark D. Rodgers
    Situation awareness is a fundamental requirement for effective air traffic control forming the basis for controller decision making and performance. To develop a better understanding of the role of situation awareness in air traffic control, an analysis was performed to determine the specific situation awareness requirements for air traffic control. This was conducted as a goal-direct task analysis in which the major goals, subgoals, decisions and associated situation awareness requirements for En Route Air Traffic Control (ATC) were delineated based on elicitation from eight experienced Air Traffic Control Specialists. This effort was supported by available task analyses and video-tapes of simulated air traffic control tasks. A determination of the major situation awareness requirements for En Route ATC was developed from this analysis, providing a foundation for future system development which seeks to enhance controller situation awareness and provides a basis for the development of situation awareness measures for air traffic control.
    The Effects of Taxiway Light Geometry, Color, and Location on Position Determination by Pilots BIBA 76-80
      Florian Jentsch
    Lack of perspective cues or abundance of lights in airport taxiway areas have been problems leading to pilot disorientation when navigating on the airport surface. Possible human factors solutions include the introduction of perspective cues through shaped lights and the reduction of extraneous light signals with shielded lights. Thirty-two pilots participated in a laboratory simulation to evaluate the effects of taxiway light geometry, color, and location on determination of position. Two new systems (shielded and shaped lights) were tested against two traditional systems (blue edge lights and green centerline lights). Subjects had to determine their position on an airport map from static, out-the-cockpit views. Contrary to expectations, the two new systems did not lead to improved performance over the traditional systems in this simulation. In fact, the pattern of means suggested that performance was better with the traditional systems than with the new ones. In the case of the number of correctly identified positions, these differences were significant. Subjects' confidence and their actual performance in position determination did not correlate. Implications for studies investigating airport surface navigation systems are discussed.

    AEROSPACE SYSTEMS: Evaluation Metrics and Inexpensive Simulation [Lecture]

    Analytic Workload Models for Flight Deck Design and Evaluation BIBA 81-84
      Victor Riley; Elizabeth Lyall; Earl Wiener
    A number of methods have been proposed to predict operator workload in complex systems. These methods depend on a variety of task attributes, including the difficulty levels of individual demands, the number of tasks performed in a unit of time, and the degree of competition between multiple demands. In this effort, twenty two methods of estimating workload were compared to determine the values of these attributes and to identify the most useful of the methods for flight deck design and evaluation.
    A Singular Value Decomposition Approach to Information Presentation Format Optimization BIBA 85-89
      Christopher A. Miller; Blaise Morton
    Glass cockpits pose a novel problem in Information Presentation Format (IPF) optimization since they invariably carry more formats than they can present any given time. In addition to optimizing individual formats and the static layout of sets of formats for information presentation, designers must now concern themselves with optimizing the overall set of formats from which a subset is drawn for presentation at any given time. Fortunately, quantitative knowledge representations and reasoning techniques, deriving primarily from research in the Pilot's Associate programs, enable the use of sophisticated mathematical analysis techniques for addressing this problem quickly and easily. We present initial work on the use of Singular Value Decomposition techniques for analyzing the "fit" between the information presenting capabilities of a set of IPFs and the information needs of a set of piloting tasks and show how this technique can be used to provide design recommendations for the global set of IPFs available for presentation in the cockpit.
    Issues in Using Off-the-Shelf PC-Based Flight Simulation for Research and Training: Historical Perspective, Current Solutions and Emerging Technologies BIBA 90-94
      Dennis B. Beringer
    Flight simulation has historically been an expensive proposition, particularly if out-the-window views were desired. Advances in computer technology have allowed a modular, off-the-shelf flight simulation (based on 80486 processors) to be assembled that has been adapted, with minimal effort, for conducting general-aviation research. This simulation includes variable flight instrumentation, forward, 45 and 90 degree left external world views, and a map display. Control inputs are provided by high-fidelity analog controls (e.g., damped and self-centering yoke, high-performance throttle quadrant, gear, flap, and trim controls; and navigation radio frequency select). The simulation is based upon two commercially available flight simulation software packages, one designed as an instrument flight trainer and the other as a "game"-type flight simulation. The provisions of these packages are discussed highlighting their particular research capabilities as well as their limitations. The comparatively low cost and ease of assembly/integration allow multiple "standardized" systems to be distributed for cooperative interlaboratory studies. The approach appears to have utility for both research and training. Preliminary experimental results are reported as a validation of the utility of the system for research.
    The Use of Personal Computer-Based Training Devices in Teaching Instrument Flying: A Comparative Study BIBA 95-99
      William F. Moroney; Steven Hampton; David W. Biers; Thomas Kirton
    The in-flight performance of aviation students trained on PC-Based Training (TDs), using "Elite" and "IFT" software packages, was compared to the in-flight performance of students trained in a FAA approved generic training device (the Frasca 141). Seventy-nine students enrolled in a Instrument Flight Training Course were trained on one of the three TDs and then flew in a Mooney 20J. Instructors/evaluators used a form, based on criteria specified in FAA's Performance Test Standards (PTS) for an Instrument Rating, to evaluate student performance on six maneuvers and two categories of general flight skills. Student performance was evaluated by course instructors and independent "Stage Check Pilots" during both the ground-based and in-flight portion of the course.
       For the factors evaluated, no significant difference was noted among those students taught in any of the TDs in either the number of trials per task or hours to instrument flight proficiency in the aircraft. However, compared to students trained on the Frasca, students trained on the PC-Based TDs required significantly fewer hours and trials per task, to reach the overall PTSs in the TDs. Additionally, training received in the PC-Based TD cost 46% less than training received in the Frasca. Finally, the cost of the PC-Based TDs, associated hardware and Software was 7.6% of the $60,000 cost of the Frasca. The authors recommend that steps be initiated to qualify PC-Based TDs as Flight Training Devices, in which instrument rating training credit can be accrued.

    AEROSPACE SYSTEMS: Human Factors and Ergonomics in Maintenance and Inspection [Symposium]

    Human Factors and Ergonomics in Maintenance and Inspection BIBA 100
      William T. Shepherd
    In 1991 the National Plan for Aviation Human Factors was published. The plan proposed a variety of research priorities for the nation's aviation industry and government entities. The FAA Office of Aviation Medicine has been conducting a research program to address the Aviation Maintenance topics identified as significant in the National Plan. The resultant research program has been recognized as the most significant maintenance-oriented human factors study in the world.
    Results of a National Field Study of a Pen Computer-Based Electronic Performance Support System BIB --
      Charles Layton; Clifford McKeithan; Jonathan Turner; Joseph Jackson; Lenear Garland
    Introducing a Practical Human Factors Guide into the Aviation Maintenance Environment BIBA 101-105
      Michael E. Maddox
    A safe and efficient air travel system depends on three elements; design, operation, and maintenance. The Human Factors profession essentially began and matured in the aviation environment. The aircraft cockpit and the skills involved in piloting have been the subjects of more human factors research than any other single topic. Likewise, the topic of aircraft design has been the beneficiary of many of the tools and procedures developed to embed human capabilities into products. The third component, maintenance, seems to receive attention only when it is shown to be a contributing factor in a mishap. In an effort to embed proper human factors principles in the aircraft maintenance environment, Congress, through the Federal Aviation Administration Office of Aviation Medicine (OAM), has mandated that more emphasis be placed on human factors in maintenance operations. A major product of this initiative is a Human Factors Guide, being developed to provide practical, useful, and usable guidance to supervisors and planners in the aviation maintenance industry. This paper describes the goals, form, and content of the new Human Factors Guide.
    Ergonomics on the Hangar Floor: Structuring the Intervention Process BIBA 106-110
      Colin G. Drury
    A methodology is demonstrated which systematically interpreted aircraft inspection tasks in human factors terms, performed projects where human / system mismatches were found, and re-integrated the project findings to provide for comprehensive intervention. A generic function description was first used to structure extensive hangar-floor observations and analysis, and potential mismatches determined. Projects were completed for each function, for example redesigned workcards for the Initiate function and lighting studies for the Search function. Integrative techniques developed were a computer-based audit program to evaluate human factors in aircraft inspection tasks, and a systematic implementation technique based on human factors teams in the hangar.
    Reducing Human Error in Aircraft Maintenance Operations with the Maintenance Error Decision Aid (MEDA) BIBA 111-114
      Rebecca Hibit; David A. Marx
    The Maintenance Error Decision Aid (MEDA) is an event-driven tool that assists a maintenance investigator to identify contributing factors and corrective actions that will prevent airplanes from being dispatched with error-induced discrepancies. MEDA attempts to influence the user to think differently about how he views and investigates maintenance error by supporting a human-centered, error investigation.

    AEROSPACE SYSTEMS: Aerospace Issues [Lecture]

    Applying Virtual Environment Technology to the Design of Fighter Aircraft Cockpits: Pilot Performance and Situation Awareness in a Simulated Air Combat Task BIBA 115-118
      Lawrence J. Hettinger; W. Todd Nelson; Michael W. Haas
    The use of multi-sensory displays for fighter aircraft cockpits is being investigated at the U.S. Air Force's Armstrong Laboratory as a means of enhancing pilot performance. The current experiment was conducted to evaluate the effect of employing such displays on the performance of a simulated air combat task. Each of four experienced US Air Force F-16 pilots flew 12 simulated missions which required them to locate and destroy four enemy bombers whose flight path was pre-programmed. Simultaneously, two other pilots were assigned to auxiliary cockpits in the laboratory and flew enemy fighter aircraft in an attempt to intercept and shoot down the primary pilot. Therefore there were three active participants in each air combat scenario. Each pilot flew six trials using a cockpit comprised of conventional F-15 flight instruments and six trials using a modified, multi-sensory cockpit. The results indicated that pilot performance and situation awareness were generally superior with the multi-sensory cockpit as opposed to the conventional cockpit, although statistical differences between the two were at best marginally significant. Nevertheless, the results suggest that if pilots were to receive advance training with the multi-sensory cockpit their performance may exceed that in the highly overlearned conventional cockpit by even more substantial amounts.
    Effect of Terrain Shape and Object Grouping on Detection of Altitude Change in a Flight Simulator BIBA 119-123
      James A. Kleiss
    Multidimensional scaling (MDS) analyses of flight simulator visual scenes reveal that both the shape of the terrain surface as well as the spatial distribution of objects on the terrain are salient to pilots flying at low altitudes. MDS is based upon similarity ratings and it was deemed important to verify the relevance of these scene properties using a performance based task in a flight simulator. The task was an ascent/descent discrimination task similar to that used in other flight simulation research. Terrain shape and elements on the terrain (texture and objects) were factorially manipulated. Presence of hills as well as the spatial organization of objects on the terrain affected performance in some conditions. A positive effect of hills is noteworthy because hills did not extend above the horizon and therefore posed no vertical obstructions. Thus, they provide relevant information for perceiving altitude change apart from the role they may play in obstructing vision or navigation.
    Development of a Speech Analysis Protocol for Accident Investigation BIBA 124-127
      David L. Mayer; Malcolm Brenner; James R. Cash
    This paper describes an initial attempt to develop a protocol for speech analysis techniques that might lead to a better understanding of the cognitive and emotional states that underlie the behavior of people involved in accidents. A tape recording of radio transmissions made by a pilot during both routine and emergency flight conditions was analyzed. Five primary speech measures were made for each statement: mean fundamental frequency (f0), range of fundamental frequencies ({Delta}f0), duration, mean amplitude and syllable count. Speaking rate (syllables per second) and two other derived measures were computed later. During routine flight, the pilot's f0 averaged 123.9 Hz, but this increased to an average of 200.1 Hz during emergency conditions. Range of f0 also increased significantly, while syllable count decreased. These changes may provide a profile of a response to extreme stress that may be useful for gaining insight into situations in which such stress is not otherwise apparent.
    A Study of Life Expectancy for a Sample of Retired Airline Pilots BIBA 128-132
      Robert O. Besco; Satya P. Sangal; Thomas E. Nesthus; Stephen J. H. Veronneau
    There is a popular belief in the aviation industry that retired pilots die at a younger age than their counterparts in the general population. If this is true, research into factors associated with this career would be of interest to the FAA as indicators of possible health factors to be monitored in the pilot population. A sample of 1494 pilots who retired at age 60 from a major U.S. airline between the study dates of April 1968 to July 1993 were surveyed. The Life Table Method was chosen as the most suitable approach to analyze the pattern of mortality for this data set. Comparisons were made with the U.S. general population of 60 year-old white males in 1980. A difference in life expectancy of more than 5 years longer was found for our sample of retired airline pilots. Half of the pilots in this sample retiring at age 60 were expected to live past 83.8 years of age, compared to 77.4 years for the general population of 60 year-old white males in 1980. The authors concluded that the question of lowered life expectancy for airline cockpit crews was not supported by the results of these data.

    AGING: Designing for an Aging Population [Lecture]

    Age Differences in the Legibility of Symbol Highway Signs as a Function of Luminance and Glare Level: A Preliminary Report BIBA 133-136
      Frank Schieber; Donald W. Kline
    Three experiments were conducted to investigate the effects of adult aging upon the legibility of simulated symbol highway signs. Each experiment employed a different set of lighting conditions: (1) daytime luminance, (2) nighttime luminance, and (3) nighttime luminance with glare. Young (ages 18-25) and middle-aged (ages 40-55) observers demonstrated small reductions in legibility when luminance was reduced from daytime to nighttime levels. However, older (ages 65-79) observers demonstrated marked losses in legibility distance with reductions in sign luminance. The introduction of a glare source (equivalent to approaching automobile headlights at 30 m) reduced sign legibility distance for the older observers but had no deleterious effects upon their young and middle-aged counterparts. The relative magnitude of the observed age, luminance and glare effects appeared to be equivalent across all signs examined.
    Reach Design Data for the Elderly BIBA 137-141
      Ursula Wright; G. Major Kumar; Anil Mital
    The increased life expectancy of the elderly may require substantial redesigning of environments in order to accommodate age related body changes. One of the most important aspects allowing the elderly to function independently is the ability to reach for items comfortably during daily activities. Designing for an independent elder requires knowledge of reach measurements that determines the optimal design of working/living environments. This paper provides reach capability design data of elderly males and females between 65 and 89 years of age. Results show that direct and indirect reach indicators decrease substantially above the age of 80. The elderly participating in this study were compared with younger cohorts, showing significantly lower reach capabilities. This indicates the necessity of considering anthropometric data, such as reach, to design for the elderly. The need is particularly dire for those above 80 years of age.
    An In-Depth Analysis of Automatic Teller Machine Usage by Older Adults BIBA 142-146
      Wendy A. Rogers; D. Kristen Gilbert; Elizabeth Fraser Cabrera
    The present study investigated the usage of Automatic Teller Machines (ATMs) by older adults. We conducted 100 telephone interviews of older adults wherein we queried subjects about their frequency of ATM usage. From this pool of individuals we chose eight frequent users and eight intermediate users to participate in an in-depth structured interview. The phone and structured interviews provided detailed information about usage patterns and general ATM knowledge of older adults. The interviewing technique provided insight into the concerns of older adults and the problems they encounter when using ATM technology. The results of this study provide information relevant to design and training for ATMs. Although the data are derived from a sample of older adults, any improvements of design, safety, or training will be beneficial to the population of users as a whole.
    Audible Performance of Smoke Alarm Sounds BIBA 147-151
      Richard W. Huey; Dawn S. Buckley; Neil D. Lerner
    This paper concerns a study aimed at selection of alarm sounds with improved audible performance characteristics for older listeners over current conventional residential smoke detectors. Many current residential smoke detectors possess alarms that have their primary frequency peak in the 4000 Hz region of the audible spectrum. Additionally, many of these alarms are constant instead of providing temporal modulation of the signal. This study analyzed a variety of alternative sounds for selection as a better choice for an "age sensitive" smoke alarm signal. The study presented a battery of candidate sounds to pairs of subjects aged 65 and older with varying levels of hearing impairment (O to 45 dB) in their own homes to see which sounds performed best in terms of detection, localization, and perceived attention-getting value. Subjects were placed in various location- and masking-based conditions within their homes during listening periods and subjected to sounds played at a constant level. A computerized system collected response data as the battery of stimuli was presented. The data showed a fairly predictable positive trend in detection and localization performance level as the frequency of the stimuli decreased from 4000 Hz to 500 Hz. The data also showed that pulsed signals were more detectable than steady alarms.

    AGING: Panel

    Assessing the Older Driver: An Interdisciplinary Approach BIBA 152-154
      John W. Eberhardt; Erik C. B. Olsen; Anthony D. Andre; Karlene Ball; Linda Hunt; Kim Harwood; Anne Corn
    Numerous groups of professionals have been studying driving and aging for many years, including human factors researchers, occupational therapists, optometrists, and special educators. Unfortunately, however, this diverse set of professionals has not joined efforts in developing comprehensive assessment techniques for older drivers. This panel represents an important step toward supporting an interdisciplinary approach to elderly driver assessment.

    AGING: Aging and Information Processing [Lecture]

    Memory Skill Acquisition for Young and Old Adults: Does Training Order Affect Learning? BIBA 155-159
      Jennifer L. Clark; Wendy A. Rogers
    The purpose of the present experiment was to identify the effects of altering the order of training for a memory search task in old and young adults. We provided subjects with extensive practice on consistently mapped (CM) and variably mapped (VM) versions of a memory search task. Half of the subjects in each age group received CM training followed by VM training and the other half received VM first followed by CM. Based on previous findings (Fisk, Rogers, and Giambra, 1990), in which older adults did not switch to a more efficient search strategy (i.e., from serial exhaustive to serial self-terminating) we predicted that older subjects who received VM training first would not adopt the most efficient strategy on subsequent CM training compared to old adults who received the CM training first. The results supported our prediction: namely, the comparison slopes were shallower (i.e., more efficient) for the older adults who received CM training first, relative to those who received VM training prior to the CM training. Order of practice did not significantly affect the performance of the young adults. These data have important implications for the development of training programs in which subjects will be required to learn several task components.
    Age Differences on a Paired-Associates Task: How Does Practice Type and Order Affect Training? BIBA 160-164
      D. Kristen Gilbert; Wendy A. Rogers
    The purpose of this research was to determine if manipulating the order and type of practice would affect the outcome of training for both young and older adults. We examined age differences in performance on a paired-associates task in which type and order of practice were manipulated. Two versions of a noun-pair associates task were used; in the consistent mapping (CM) version the noun-pairs did not change from trial to trial; in the varied mapping version (VM) the noun-pairs changed from trial to trial. The CM task allowed the subjects to learn the noun-pairs whereas the VM task required that subjects always refer to a key in order to perform the task. Two groups of subjects were trained and the order in which they received the CM and VM versions was manipulated between groups. There were group differences in initial performance on the CM task for both young and older adults. The data indicate that having performed the task at all provided some benefit in terms of reaction time. The subjects were able to acquire the skill of performing the task in the first version they performed and this skill acquisition aided their subsequent performance. In addition, the benefits of prior practice were longer-lasting for older adults relative to young adults.
    Age Similarities in Complex Memory Search: An Extension of Dual Process Theory BIBA 165-169
      Brian P. Cooper; Arthur D. Fisk
    Understanding age-related similarities and differences in development of cognitive skill is important as it can inform theories of cognitive aging as well as serve the pragmatic value of informing those individuals who are developing age-related interventions for numerous activities of daily living. We investigated both the performance and learning of skilled memory search, a task that has shown age-related similarity in performance if sufficient consistent practice is provided, to determine if training guidelines for this class of processing activities is applicable to both young and old adults. Old and young adults received memory search training, and then the participants were transferred to untrained exemplars of the trained memory set categories. The results suggest that both young and old adults are, at least to some extent, learning at the semantic-category level. This study provides additional evidence that training guidelines derived from an automatic and controlled processing framework can be applied to an older adult population in tasks which have memory search components.
    Perceptual Organization and Grouping Factors: Age Related Effects BIBA 170-174
      Darryl G. Humphrey; Arthur F. Kramer; Sheryl S. Gore
    Older adults have evidenced a poorer ability to use grouping factors in such tasks as Embedded Figures, Incomplete Figures, and partial report. Difficulties in disambiguating the findings of these studies has left unanswered the cause of this age-related difference. By taking into account age-related differences in visual short-term memory, the results of the current study suggest that older adults maintain the ability to capitalize on the perceptual organization of the visual environment as a means of facilitating recall performance. These results have implications for the design of information displays, product labels, codes, and instructions.

    COMMUNICATIONS: Hands-On Answers on Personal Digital Assistants: Part II [Symposium]

    Hands-On Answers on Personal Digital Assistants: Part II BIB --
      John Chin; Elizabeth B. N. Sanders

    COMMUNICATIONS: Design Issues in Telecommunications [Lecture]

    The Development of a Touch Screen Based Communications Terminal BIBA 175-179
      Bruce Thomas; Ian McClelland
    This paper discusses the design of a communications terminal for professional applications. The development work included visits to sites to capture requirements through interview and observation of working practices, and to get insight into typical communication tasks. A clear task focus was maintained during the design phase by using a dialogue description tool developed in-house to support the integration of the dialogue specification, the graphic design and the software design. Customer and operator feedback on the design was obtained. The success of the design can be attributed to a direct involvement of users in the development process and to the integration of different specialists in the development team.
    Telepresence in Videocommunications BIBA 180-184
      Angela Prussog; Lothar Muhlbach; Martin Bocker
    The paper discusses factors that affect the impression of telepresence in video-communications. Telepresence is experienced by interlocutors to the extent to which natural visual cues from the remote site are adequately transferred by the medium. The paper reports on two experimental Human Factors studies investigating the effects of various features of videoconferencing systems in terms of, inter alia, the conferees' impression of telepresence as well as user satisfaction and the willingness to use those systems. Within the framework of Experiment 1 the system features that were varied were the scale of representing the conferees (natural vs. reduced size) and the representation of the conferees' surroundings (small vs. large sector of the remote room). In Experiment 2 the system feature being tested was the stereoscopic representation of the conferees. Results showed that both the natural-size representation of conferees as well as the stereoscopic representation increase the impression of telepresence. The expected benefits of a representation of the conferees' surroundings could not be verified. Given a fixed size of the screen, the trade-off between the conferees' size and the representation of surroundings is in favor of the natural size representation.
    Stereoscopic Telepointing in Videocommunications BIBA 185-189
      Detlef Runde; Martin Bocker
    Stereoscopic telepointing to be employed inter alia in cooperative telework applications yields many benefits but also poses a number of problems addressed in a study with 96 subjects under four different conditions. For two conditions, 3D-input devices were designed implementing different input metaphors. The 'Light Beam Metaphor' is analogous to pointing to objects with a slide show pointer or laser pointer. The 'Reference Space Metaphor' provides the users with the possibility of pointing to details of an object in such a way as if a re-sized model of the object was present in front of them and within reach of their hands. The other two conditions were stereoscopic and monoscopic control conditions without pointers. The subjects' task was to identify differences between a remote and a local object within a limited time. The results show that the Light Beam Metaphor pointer was easier to handle and conformed to a larger degree to the users' expectations, whereas the Reference Space Metaphor pointer received better subjective ratings on efficiency and Telepresence. The analysis of the results of all four conditions established the benefits of 3D over 2D representations for object-oriented communicative situations in terms of appeal and the impression of depth.


    Human Factors Issues on the Information Highway BIBA 190-193
      James F. Sorce; Arnold M. Lund; Joel S. Angiolillo; George J. Boggs
    This past year has been unique as planning and construction of the infrastructure to bring interactive video services to homes, schools, and businesses has begun in earnest. Ground breaking activity on new applications that use this evolving infrastructure will be intense well into the next century. It is appropriate, therefore, to examine the human factors issues that are being identified in these early stages. The problems are large, and years of research will be required before they are resolved. This panel will bring together people working on the "information highway" to discuss the issues they have been facing during these early stages, as the forms the new applications and interfaces are going to take just begin to appear.

    COMPUTER SYSTEMS: Analysis and Modeling of Use of Procedures in Dynamic Worlds: Implications for the Design of Computer-Based Procedures [Symposium]

    Analysis and Modeling of Use of Procedures in Dynamic Worlds: Implications for the Design of Computer-Based Procedures BIBA 194
      Emilie M. Roth; Kevin M. Corker
    In dynamic high risk environments, such as aviation, air traffic control, and nuclear power plant operations, when emergencies arise, the burden of diagnosing and developing a response strategy in real time can be very high. One response to this problem that has been adopted in a number of domains is to develop preplanned response strategies in the form of procedures that the person-on-the-scene is expected to follow in dealing with the emergency. This symposium examines the cognitive demands inherent in responding to emergencies when procedures are available, and the implications for development of computer-based procedures and related decision-support systems.
    Man-Machine Design and Analysis System (MIDAS) Applied to a Computer-Based Procedure-Aiding System BIBA 195-199
      Douglas G. Hoecker; Kevin M. Corker; Emilie M. Roth; Melvin H. Lipner; Marilyn S. Bunzo
    Difficult issues in design criteria confront the designers of human-computer interaction (HCI) implementations for future power plant control rooms. Such HCI-intensive control-room elements include "soft" controls and displays, computerized procedures, alarm presentations, and support for cooperative information-sharing among crewmembers. This shift in technology, from dedicated controls and displays in fixed locations to multifunction computer-driven operator workstations and wall displays, must focus not only on the required functionality of these interfaces, but also on their crafting and integration in such a way as to minimize the likelihood of operator error.
       With the objective of providing early insight into the cognitively error-prone consequences of selected interface dynamics, we are adapting a computer-based cognitive modeling tool, the Man-machine Integrated Design and Analysis System (MIDAS), to quantitatively model certain user requirements for operating different types of interfaces while dealing with high-consequence events in a control room setting. MIDAS was conceived and is being developed as a joint Army/NASA program a the NASA Ames Research Center to test different design approaches to computerizing the cockpits of advanced commercial and military aircraft
       This report presents preliminary results from a project to adapt the MIDAS tool to the nuclear control room domain. These results have enabled comparative observation of cognitive loading depending on whether a supervisor uses computerized procedures or paper procedures to direct crew response to a plant trip event. The results suggest that each technology for procedural support, in its current respective implementation, has its own strengths and weaknesses at different points in the control task dialog.
    Operator Performance in Cognitively Complex Simulated Emergencies: Implications for Computer-Based Support Systems BIBA 200-204
      Emilie M. Roth
    An empirical study was conducted examining operator performance in cognitively demanding simulated nuclear power plant emergencies. During emergencies operators follow highly prescriptive written procedures. The objectives of the study were to understand and document what role higher-level cognitive activities such as diagnosis, or more generally 'situation assessment,' play in guiding operator performance, given that operators utilize procedures in responding to the events. The study examined crew performance in two simulated emergencies. Up to 11 crews from each of two plants participated in two simulated emergencies for a total of 38 cases analyzed. Crew performance was videotaped and partial transcripts were produced and analyzed. The results revealed a number of instances where higher-level cognitive activities such as situation assessment and response planning enabled operators to handle aspects of the situation that were not fully addressed by the procedures. This paper describes these cases and discusses their implications for the design of computer-based support systems.
    Operating Procedures: Do They Reduce Operator Errors? BIBA 205-209
      Sharolyn A. Converse
    Computerized operating procedures have been suggested as a mechanism for reducing human error in nuclear power plants. The Computerized Procedures Manual (COPMA-II) is an electronic procedure system that can be used to execute procedures, to track progress through plant procedures, and to automatically monitor plant parameters. To evaluate the effectiveness of COPMA-II, eight teams of two licensed reactor operators operated a scaled pressurized water reactor under normal and accident conditions, using both COPMA-II and traditional paper procedures. Error rates, times to initiate procedures, times to complete procedures, and subjective estimates of workload were collected for each scenario. The most interesting finding of the study was that, for one accident scenario, performance with COPMA-II was twice as accurate as performance with paper procedures. However, operators initiated responses to both accident scenarios fastest with paper procedures. Procedure type did not moderate time to complete procedures.
    Network Modeling of Nuclear Operator Procedures BIBA 210-214
      Ron Laughery; J. Persensky
    Research and evaluation on human factors issues can be very expensive owing to 1) the high cost of running experiments and 2) high inter-team variability which makes it necessary to run large numbers of subjects to get stable estimates of performance. Increasingly, the engineering disciplines are looking towards computer modeling as a means of predicting performance as a function of engineering design. Human factors engineering has that goal as well. This paper presents the results of a validation study that evaluated a human performance modeling technology termed task network modeling. Task network models were built of a crew executing two emergency procedures and one normal procedure. For each of these three procedures, one model was built reflecting the use of paper procedures and one reflecting the use of computerized procedures. Model predictions were then compared to data on actual crews performing under identical conditions. In general, the model predictions were representative of actual performance, although a number of issues arose that should be addressed prior to using these models as a technical basis for regulatory action.

    COMPUTER SYSTEMS: Developing Supporting and Cooperative Systems [Lecture]

    Electronic Performance Support System Model BIB --
      James R. Williams; Gordon Larson
    The Impact of Group Decision Support Systems on Group Consensus Processes and Outcomes BIBA 215-219
      Suvit Nopachai; Sherry Perdue Casali
    An experiment was conducted to examine how the use of a group decision support system (GDSS) influences the formation of group consensus. In a task requiring group members to jointly prioritize a list of items, 12 groups of eight members each were randomly assigned to one of three experimental conditions involving different levels of technological meeting support: (1) a group decision support system, (2) a manual counterpart to the structure imposed by the GDSS, and (3) no structured support. Measures of group consensus and perceived consensus, decision quality and perceived decision quality, and perceived opportunity to express views were made. The results revealed that the measures of consensus, decision quality and perceived decision quality, and perceived opportunity to express views were all similar across the three levels of technology investigated. Only perceived consensus was found to vary across conditions. The practical implications of these results are discussed.
    Cooperative Human-Computer Decision Making: An Experiment and Some Design Implications BIBA 220-224
      Gunilla A. Sundstrom; Anthony C. Salvador
    Creating useful dialogues between human and automated decision makers (i.e., intelligent agents) is a critical design aspect of any effective decision support environment. However, surprisingly few studies have examined the various factors influencing the way a human decision maker interacts with various types of intelligent agents. In the present work, one such factor was examined, namely the confidence expressed by the agent about its own conclusions. Subjects were trained in a network management fault diagnosis task. They were then asked to accept or reject a fault diagnosis generated by the automated decision making agent. The automated decision maker presented its fault diagnosis with an associated confidence indication expressed as a probability. Subjects were required to decide whether to accept or reject the automated decision maker's diagnosis. To conceive an informed response, subjects were able to examine various types of information related to network performance. The results indicated that the higher the confidence level presented by the automated decision maker, the more likely it was that the human decision maker would accept the automatically generated diagnosis. Thus, the higher the confidence level of the automated decision maker, the more likely subjects were to accept a wrong decision. Moreover, subjects examined fewer pieces of information in situations when the automated decision maker expressed a high level of confidence.
    Cooperative Communications in Dynamic Fault Management BIBA 225-229
      Leila J. Johannesen; Richard I. Cook; David D. Woods
    The motivation for this research is to further theory on the development of artificial intelligence systems that function as "team players" in dynamic fault management applications. One challenge is effectively supporting the practitioner in understanding the assessments and actions of the intelligent system. The typical expert system approach to explanations is not well suited to the cognitive demands of dynamic fault management. In order to gain insight into effective cooperative interaction in dynamic fault management, we have undertaken a field of study of practitioners in one such domain, anesthesiology. We analyze the findings using the theoretical framework of a common ground and common frame of reference.


    Human Perception and Performance in 3D Virtual Environments BIBA 230-234
      Elizabeth Thorpe Davis; Gregory M. Corso; Woodrow Barfield; Robert G. Eggleston; Stephen Ellis; Bill Ribarsky; Christopher D. Wickens
    Virtual environments have the potential to become very significant tools both in the civilian and military sectors. They offer a new human-computer interface in which users actively participate and are totally immersed in a computer-generated 3D virtual world. Important applications of virtual environments include the scientific visualization of complex data sets, the operation of remotely manipulated vehicles or teleoperators, the display of aircraft locations for air traffic control, simulated flight training, simulated driving training, teleoperated surgery as well as medical training and skill acquisition in surgery.
       Because virtual environments offer greater flexibility than most traditional HCI interfaces, those and other tasks may be better handled by virtual environments than by more traditional HCI interfaces. For example, virtual reality technology offers the capability of 3D or 2D representations, egocentric or exocentric 3D viewpoint, stereoscopic or monoscopic views, dynamically changing or relatively static representations as well as the availability of multi-sensory information (e.g., visual, auditory, and tactile inputs) and of perceptual-motor interactions. Yet, current VR systems still suffer from technical limitations that may restrict their usefulness. These technical limitations include poor spatio-temporal resolution of visual, auditory, and haptic images; cross-sensory image registration; and inaccuracy of head and eye tracking devices. Some of these limitations may be overcome by advances in the technology while other limitations may be overcome by cleverly adapting the VE system to exploit the capabilities and limitations of human perception.
       In all applications of virtual environments, human spatial perception plays a crucial role. For example, distance, elevation, and azimuth information is used to determine where objects are located. Yet, the perceived spatial location of an object may be ambiguous within a given display. Stereoscopic displays can provide humans with visual cues to disambiguate this information. But, there are other ways to resolve this ambiguity, such as the use of other visual cues or of other sensory modalities (e.g., auditory and haptic senses). Moreover, determination of the "best" perceptual cues and the "best" sensory modalities may be task dependent.

    COMPUTER SYSTEMS: Visual Perception in Virtual Environments [Lecture]

    Relative Effects of Color-, Texture-, and Density-Coding on Visual Search Performance and Subjective Preference BIBAK 235-239
      Gary Perlman; J. Edward, II Swan
    Previously, it had been found that texture-coding was ineffective at reducing search time (Perlman & Swan, 1993). In the experiment reported here, 16 subjects searched for blank-, color-, texture-, and density-coded targets of varying complexity in a naturalistic task. The data showed that all non-blank methods were significantly and about equally more effective at reducing search time than blank-coding (no coding). The difference of outcome with previous results is explained by task simplification and by the control of possibly confounding factors. The difference suggests that coding techniques using texture, and possibly other methods, should be evaluated in context. The similar performance of color-, texture-, and density-coding is explained by the use of equal-saturation and equal-brightness colors. Recommendations for the design of effective coding methods and for future research are discussed.
    Keywords: Screen design, Coding methods, Visual search, Highlighting, Color, Tonal, Density, Texture fill
    Visual Analysis of Scientific Data: Comparison of 3D Topographic, Color, and Gray Scale Displays in a Feature Detection Task BIBA 240-244
      David H. Merwin; Michelle A. Vincow; Christopher D. Wickens
    Several display techniques were compared for representing scientific data in the context of a feature detection task. The data sets were rendered on a Silicon Graphics workstation using four display formats: linearized gray scale; rainbow scale; reduced hue (blue-green-yellow-white) scale; and a 3D-topographic formal viewed in stereo. The task involved searching for features that were embedded in scientific data sets consisting of two spatial and one scalar variable. Data sets were drawn from three scientific domains: Landsat, medical MRI, and global atmospheric data bases. Two types of features were embedded within the data sets: circular (blob-like) discontinuities, and linear (cliff-like) discontinuities. Results showed a general advantage for the gray scale, and a marked disadvantage for the 3D-topographic format in both accuracy and response latency. Performance in the two color scale formats was intermediate, with the reduced hue scale supporting faster, if not more accurate performance than the full rainbow scale. Performance differences were found across data base domains, as well. Directions for future research are discussed.
    Asymmetrical Spatial Accuracy in 3D Tracking BIBA 245-249
      Shumin Zhai; Paul Milgram
    This paper reports on asymmetrical spatial accuracy of human subjects in tracking of an object which moves randomly with 6 degrees-of-freedom (DOF) in a 3D environment. It was found that, for translational errors, RMS deviations in the depth (Z) direction were 40% higher than those in the horizontal (X) direction, for an experimental display which provided binocular disparity (stereopsis), perspective and partial occlusion cues. In general, translational tracking errors in the vertical (Y) direction were greater than those in the X direction and smaller than those in the Z direction. In early stages of practice, vertical errors were similar to those in the Z direction, but as learning progressed, errors in the X and Y dimensions converged. These finding were consistent across two types of controllers and different tracking paths in the 3D environment. It would appear that horizontal movement requires higher attentional resource priority over vertical movement in such a tracking task.
    Investigation of Errors in Perception of Stereoscopically Presented Virtual Object Locations in Real Display Space BIBA 250-254
      Akira Utsumi; Paul Milgram; Haruo Takemura; Fumio Kishino
    This paper describes studies on perception of virtual object locations. It explores the behavior of some factors related to depth perception, especially the effect of inter-pupillary distance (IPD) mismatch and the interplay of image blur and binocular disparity. IPD mismatch (which is caused by errors in estimation of the parameter) results in a certain perceptual error of virtual objects' depth. Blur of images is also a source of error in depth representation. It was found, in some cases, to be a very strong depth cue. The results of a series of experiments conducted on IPD mismatch and image blur are also presented.

    COMPUTER SYSTEMS: User Interface Navigation and a Model for Explicit Research-Practice Interaction [Symposium]

    User Interface Navigation: And a Model for Explicit Research-Practice Interaction BIB 255
      Randolph G. Bias; Douglas J. Gillan
    Cognitive Psychophysics and Mental Models BIBA 256-260
      Douglas J. Gillan
    With the increased emphasis on incorporating users' mental models in design of interfaces comes an increased need for instruments for measuring mental models. Two frequently-used instruments for measuring people's mental representations of physical space are drawing a map and rating the distances between pairs of points in the space. The assumption underlying the present research was that mental representations of space (Mi) are transformed to become a subject's response (Ri), yielding the following functions: Rdrawi =fr{sub:d}(Mi) + ed (for drawing a map), Rratei =fr(Mi) + er (for making category ratings), and Rnavigatei =fn(Mi) + en (for navigating). If each of these functions were equivalent, then the correlations among the different measurement methods should be high. Subjects either drew maps in two sessions, provided category ratings of the distances between pairs of locations in two sessions, or drew maps in one session and rated distances in a second session. The correlations were significantly lower when subjects switched between rating and drawing than when they performed the same response in both sessions. These data suggest that the functions relating the mental representation to a response differ between drawing and rating. The discussion focuses on methods for measuring mental maps and the use of mental map data in designing spatial interfaces (including interfaces to information spaces).
    Evaluating Mental Model Elicitation Methods BIBA 261-265
      Nancy J. Cooke; Anna L. Rowe
    Researchers have developed and applied a number of methods for measuring mental models. Unfortunately not only is the mental model construct ill-defined, but the basic research associated with it offers little guidance concerning the selection of a method for a particular application. In this paper a program of research is presented that is designed address this shortcoming. Specifically, the research involves a comparative evaluation of methods to measure mental models on the basis of the relationship between the method's output (i.e., the mental model) and the criterion of primary importance to the problem (e.g., task performance, user acceptance). It is assumed that a method should be selected on the basis of its ability to generate output that is predictive of the criterion of interest. It is likely that because the methods tap different aspects of a mental model, they will predict performance well on some tasks and criteria, but not others. As an example of this approach, data are presented that help to select the best method for measuring technicians' mental models of an electronics troubleshooting task.
    Guiding Instruction in Hypermedia BIBA 266-270
      Michael Hillinger; Donald J. Leu
    While hypermedia can provide flexible and rapid access to information in multiple mediums its navigation can be daunting to an unfamiliar user. This paper describes a prototype hypermedia system for training the components of a turbine engine. Designed as a content-rich hypermedia substrate combined with an independent guide, the system provides the novice with structure without impeding exploration. Results of a comparative study indicate that users unfamiliar with the topic learn more when the guide is available while users already comfortable with turbine concepts learn targeted information better without the guide.
    Navigating on the Information Highway BIBA 271-274
      Arnold M. Lund
    The "information highway" is being created now, and the design task is monumental. Some of the most critical problems in designing a navigation environment have never been addressed before, and developers are demanding that either we (as human interface designers) supply answers now or they will make up their own answers. There is too little time and there are too few resources to fully explore interesting theoretical issues, and yet the results of such exploration (if on the right topics) could be critically important. This paper will review some of the practical design issues that Ameritech has identified as being important in defining a navigation environment, and approaches we have taken to those design issues. These approaches have been shaped by a lack of design guidance in some areas, and a finite set of resources (especially time). The paper will also identify directions where research would be useful, and time frames during which the results will still be valuable.

    COMPUTER SYSTEMS: Virtual Reality and Virtual Environments [Lecture]

    Virtual Reality as a Human Factors Design Analysis Tool for Architectural Spaces -- Control Rooms to Space Stations I: Objective Measures BIBA 275-279
      Joseph P., II Hale; Mary Lynne Dittmar
    One class of Virtual Reality (VR) applications is as a Human Factors design analysis tool for work areas and other architectural spaces. A study was conducted to compare subjects' qualitative and quantitative judgments of two "real" world control rooms at the Marshall Space Flight Center (MSFC) and their corresponding virtual counterparts. The overall Independent Variables (IVs) were World (Real/Virtual) and Room (PCR/SIM) with Gender and World Order (Virtual-Real/Real-Virtual) as blocking variables. Nested within Room were range and relative range estimations. Range estimations were comprised of two IVs: 1) Item (Object/Surface) and 2) the Item's Range from the observer (Near/Far). The relative range estimations were comprised of two IVs: 1) Field-of-View (FOV) (Same/Different, i.e., whether or not the subject can see both objects simultaneously in the same FOV) and 2) the objects' Distance from the observer (Close/Away). There appears little difference between real and virtual worlds in one's ability to differentiate and estimate gross distances and to discriminate small relative range differentials within the same FOV. For different FOVs, this discrimination ability starts to deteriorate in the real world and is lost in the virtual world. There is also a clear World main effect of increased time to make judgments in the virtual world. The different perceptions, and the longer response times, point to a level of filtering occurring in the virtual environment that must be carefully considered when deciding where and how to use VR as a Human Factors analytical tool.
    Virtual Reality as a Human Factors Design Analysis Tool for Architectural Spaces -- Control Rooms to Space Stations II: Subjective Measures BIBA 280-284
      Mary Lynne Dittmar; Joseph P., II Hale
    The Architectural Space Questionnaire (ASQ) was developed and employed in order to assess subjects' impressions of four different environments (two real and two virtual rooms) at the NASA Marshall Space Flight Center. The ASQ consists of 18 adjective pairs, arrayed in a 7-point, Likert scale format. Subjects first participated in a variety of distance estimation tasks in the Spacelab Payload Control Room and the Simulation Control Room and in their virtual reality (VR) analogs. After their experience in each room, subjects responded to the ASQ, selecting one value on each adjective pair continuum which best described their impression of the room they were in. The results indicated that the ASQ is sensitive to structural differences between real rooms. Differences between virtual rooms were minimal, possibly due to the absence of visual cues such as lighting and texture in that environment. Implications for the use of VR as a design tool are explored.
    A Componential Model of Human Interaction with Graphs. III. Spatial Orientation BIBA 285-289
      Douglas J. Gillan; S. Mark LaSalle
    The Mixed Arithmetic-Perceptual (MA-P) model of graph comprehension proposes that graph users apply combinations of component processes -- including Searching for indicators, Encoding the value of indicators, performing Arithmetic Operations on the values, making Spatial Comparisons among the indicators, and Responding -- when they answer questions from a graph. 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 the use of another component process -- mental rotation -- in interacting with star graphs. Subjects used two star graphs to answer comparison and difference questions in which the differences in orientation of the indicators in question varied from 0 to 288°. The results showed a nonmonotonic change in response time with the difference in orientation. The discussion addresses the effects of mental rotation in reading displays and the role that rotation may play in the hierarchy of graph effectiveness proposed by Cleveland and McGill.
    Frame of Reference in Posture Specification for Computer-Aided Ergonomic Analysis BIBA 290-294
      Xudong Zhang; Yili Liu; Don Chaffin
    An experiment was conducted to examine the effect of the congruency between the reference frame adopted to perceive and record postures and the one employed in a computer-aided ergonomics software on human posture specification performance. The role that the interface can play in enhancing the congruency was also investigated. The subjects were presented with the photographs of a working posture, and were required to manipulate the human stick figures generated by the ergonomics software to match the posture in the photographs. The experiment showed that the congruency played a significant role in facilitating the performance of posture specification for ergonomic analysis. It also demonstrated a clear advantage of using a 3-D humanoid display to improve the congruency when it is not achievable in the pre-analysis posture data-collection. Implications for ergonomic job analysis and ergonomics software design are discussed.

    COMPUTER SYSTEMS: User Interface Design Issues [Lecture]

    Design of Skill-Based Adaptive Interface: The Effect of a Gentle Push BIBA 295-299
      Qing Gong; Gavriel Salvendy
    To accommodate individual skill differences in using a computer interface, a skill adaptive interface was designed and tested. Current human-computer interaction modes can be classified into two types, recall and recognition based interfaces. They have different memory requirements and generally allow different operating speeds and learning time. However, a static combination of the two interface modes has drawbacks. The dynamic skill adaptive interface introduced in this study tries to eliminate these problems without sacrificing the advantages from either interface modes by gently 'pushing' users to switch to the appropriate interface mode. Experiment showed that the adaptive interface can yield significant better performances than the static hybrid interface for certain groups of users.
    User Interface Design Guidelines for Computer Accessibility by Mentally Retarded Adults BIBA 300-304
      Gretchen L. Robertson; Deborah Hix
    An exploratory three-phase study examined the ability of adults diagnosed as moderately developmentally disabled to successfully use a personal computer, input devices preferred, and user interface design factors to be considered when designing or selecting applications for this population. Phase I observed the reaction of the participants, none of whom had ever used a computer, to a graphical user interface. In Phase II usability tests compared the mouse, the trackball, and the touchscreen to gather heuristic data on input device preference and develop user interface design guidelines for applications for the target population. Phase III tested the guidelines by developing two prototype games: "Shopping," designed to teach money-handling skills, and "Getting Dressed," to teach a basic life skill. Phase I showed that participants liked and understood the graphical user interface. All could use the touchscreen, and most could use the mouse. Phase II usability testing found that the mouse was preferred over the touchscreen and the trackball, although its drag-drop times were longer. Reasons given were less fatigue and greater control. Phase III found participants preferred screens that allowed them to control the action, that quick or unexpected screen responses were upsetting, and that strong, realistic visual feedback was important. The study is seen as a first step in developing guidelines to make the computer accessible to those with moderate developmental disability.
    The User Interface Design Process: The Good, the Bad, & We Did What We Could in Two Weeks BIBA 305-309
      Marta A. Miller; Reynold P. Stimart
    Conventional wisdom inside human factors circles says that the integration of user interface design processes into the software development cycle is the best way to improve the usability of software products. While there is no problem convincing human factors practitioners of this, frequently there is still a need to demonstrate the effectiveness of user interface processes to product development teams and management. Mayhew (1992) suggests that it is not enough to be able to apply human factors knowledge. Successful user interface design must include buy-in from outside of the user interface organization. To demonstrate the effectiveness of a user interface design program, data from usability tests on three versions of a product were analyzed. The oldest version of the product was developed without the inclusion of any user interface design processes. The second version of the product had minimal involvement of user interface practitioners late in the development cycle. The newest version of the product was developed with the user interface design processes fully integrated into the software development cycle. The data indicate that user interface design processes do impact usability, as measured by speed, accuracy, and subjective measures. Furthermore, user interface processes which are part of the software development cycle, as opposed to just a side effort by user interface practitioners, seem to have a much greater impact on usability.
    Navigation in the Computer Medium: A Cognitive Analysis BIBA 310-314
      Jennifer Watts
    The goal of this research is to provide a cognitive analysis of navigation in the computer medium. As the complexity of computerized information systems increases, interface designers face the formidable challenge of supporting navigation within these systems to allow users to quickly obtain information relevant to their tasks and goals. Instead of focusing solely on the comparison of a small subset of proposed techniques or theories for aiding navigation, this study investigates how people handle navigation within the natural context of a familiar computer environment, and reveals processes that can be better supported in order to aid navigation. Both a field study and a field experiment were conducted. The results of these studies provide evidence to support previous navigation-related theories and contribute to a pattern of navigation behavior that has been observed in other domains like anesthesiology and nuclear power. In addition to describing the characteristics of the computer medium that influence people's ability to navigate, this paper will also discuss typical navigation problems that arise in this medium, and how people change their behavior and adapt to computer systems to overcome these problems.

    COMPUTER SYSTEMS: Integrating Human Factors within Software Engineering Practices [Symposium]

    Integrating Human Factors within Software Engineering Practices BIB --
      Georgia K. Green
    Integrating Human Factors with Software Engineering Practices BIBA 315-319
      William E. Hefley; Elizabeth A. Buie; Gene F. Lynch; Michael J. Muller; Douglas G. Hoecker; Jim Carter; J. Thomas Roth
    Engineering processes and methodologies used in building tomorrow's systems must place a greater emphasis on designing usable systems that meet the needs of the systems' users and their tasks. This paper identifies the need for defining human factors and human-computer interaction (HCI) engineering activities that contribute to the design, development, and evaluation of usable and useful interactive systems, and presents a rationale for integrating these activities with software engineering and incorporating them into the system life cycle.
    Discussion of Results of Seminar on "Integrating Human Factors within Software Engineering" BIB --
      William E. Hefley

    COMPUTER SYSTEMS: Input Techniques [Lecture]

    The Development and Evaluation of the Keybowl: A Study on an Ergonomically Designed Alphanumeric Input Device BIBA 320-324
      Peter Joseph McAlindon
    This paper provides a description and discloses preliminary findings of a newly designed alphanumeric keyboard called the Keybowl. The Keybowl was designed and developed to provide a solution to the multi-million dollar a year problem of Carpal Tunnel Syndrome (CTS) as it relates to typing. The Keybowl totally eliminates finger movement, minimizes wrist movement, and uses the concept of concurrent independent inputs (a.k.a. chording) in which two domes are moved laterally to type. Initial results indicate that users of the Keybowl typed an average of 52% of their regular keyboard speed in as little as five hours. In regard to ergonomic advantage, flexion/extension wrist movements have been reduced by an average of 81.5% while movements in the ulnar/radial plane were reduced by an average of 48%.
    The Use of Word, Phrase, and Intent Accuracy as Measures of Connected Speech Recognition Performance BIBA 325-329
      Tim Barry; Tom Solz; John Reising; Dave Williamson
    Eleven subjects participated in a study designed to test the accuracy of a newer-generation connected speech recognition system using a 49 word vocabulary likely to be used in an aircraft cockpit environment. The 49 vocabulary words were used to create 392 test phrases. These phrases were divided into three groups: Complex phrases, which contain more than five words, and two groups of Simple phrases, which contain 5 words or less. The simple phrases were divided into Simple Alternate and Simple No-Alternate phrases, depending on whether or not the phrase was the only one in the entire vocabulary capable of carrying out a particular action once recognition occurred. Performance of the recognition system was measured with three accuracy statistics: Word accuracy, the most commonly reported statistic in speech recognition research, phrase accuracy, which is gaining popularity in connected speech recognition research, and intent accuracy, which is probably the most relevant statistic that could be reported in research of this type. Significantly different word, phrase, and intent accuracy results were obtained for the three different phrase types.
    A Comparison of Three Methods of Character Entry on Pen-Based Computers BIBA 330-334
      I. Scott MacKenzie; R. Blair Nonnecke; J. Craig McQueen; Stan Riddersma; Malcolm Meltz
    Methods for entering text on pen-based computers were compared with respect to speed, accuracy, and user preference. Fifteen subjects entered text on a digitizing display tablet using three methods: hand printing, QWERTY-tapping, and ABC-tapping. The tapping methods used display-based keyboards, one with a QWERTY layout, the other with two alphabetic rows of 13 characters. ABC-tapping had the lowest error rate (0.6%) but was the slowest entry method (12.9 wpm). It was also the least preferred input method. The QWERTY-tapping condition was the most preferred, the fastest (22.9 wpm), and had a low error rate (1.1%). Although subjects also liked hand printing, it was 41% slower than QWERTY-tapping and had a very high error rate (8.1%). The results suggest that character recognition on pen-based computers must improve to attract walk-up users, and that alternatives such as tapping on a QWERTY soft keyboard are effective input methods.

    COMPUTER SYSTEMS: Usability [Lecture]

    Measuring Perceived Task Difficulty Using Magnitude Estimation: A Demonstration and Replication BIBA 335-339
      Sabina Alteras-Webb; Debra K. Dekker
    The proliferation of sedentary, more cognitively demanding computer-mediated work, calls attention to the need for methods to measure mental work load. The prevent research describes two experiments in which participants performed a machine paced task of entering five and/or nine digit zip codes into a computer. The zip code data was prevented on a computer screen for twelve four minute trials where the rate of zip code presentation varied from trial to trial. Using the psychophysical scaling method of magnitude estimation, participants made a judgment of task difficulty after each trial period. In Experiment 1, four females participated in a repeated measures within-subjects design performing each digit task condition for five consecutive days. In Experiment 2, a between-subjects design was adopted where 42 females performed either the five or the nine digit data-entry for only one testing session. Regression analyses using the independent variable of stimulus presentation rate and the dependent variable of judgments of perceived difficulty resulted in R²s of .90 or better for both digit conditions in both experiments. T-tests were conducted to see if different task parameters would affect difficulty judgments; these were statistically significant to the .001 level in both experiments. The results support the notion that magnitude estimation is a reliable method for scaling subjective perceptions of difficulty, which may be an important component of mental workload.
    Experimental Validation of Navigation Workload Metrics BIBA 340-344
      Jack C. Schryver
    Advanced computer interfaces in the control room provide limited display area, and information is represented in large-scale display networks. Display navigation may generate disorienting effects, require additional resources for window management, and increase memory and data integration requirements. An experiment was conducted using an elementary Safety Parameter Display System for Pressurized Waler Reactors to validate fourteen proposed metrics of navigation workload. Participants were asked to monitor one or two parameters, and answer questions after navigating a prescribed distance in the network. Analyses of variance of a modified task load index and subscales (confidence, disorientation, effort) supported the claim that navigation of large-scale display networks can impose additional mental load. Eye-gaze and other objective metrics were not validated, indicating needs for more refined probes and data reduction algorithms.
    Graphical Feedback System to Effectively Support User's Task BIBA 345-349
      Toshiya Yoshimune; Katsuhiko Ogawa
    The book metaphor approach was created to simplify database access. The intent was to improve access speed and comfort. In 1990, we created an advanced book metaphor interface (BMI) to a set of about 300 design guidelines. The user interacts with the guidelines through a 'book like' screen and operations such as the table of contents, the index, or browsing. Experiments revealed, however, that the BMI did not offer a significant improvement over the equivalent printed version of the guidelines.
       The BMI was more comfortable but users did not perform the task, correcting an example of a bad data input screen, any more rapidly. The problem was that novice users did not understand the tools offered by the BMI and so failed to use them in the optimum manner.
       An agent was added to the BMI that monitors the user's commands and, when the user deviates from the optimum procedure, graphically suggests what the more correct procedure would be.
       The subjects of the usability analysis were software designers who did not have background in human factors. They were instructed to design screens through the use of the guidelines using the BMI. The agent was provided to only half of them. The usability analysis finds that the new BMI realizes higher productivity and increased user acceptance.
    Statistical Process Control Charting Applied to the Analysis of Human Performance in Computer-Supported Environments BIBA 350-354
      Janine A. Purcell
    To develop usable Human-Machine Systems, we need Tools to evaluate and measure the length of learning periods, error rate, response time, and transfer of learning in the human operators of these systems (Whiteside, Bennett, and Holtzblatt, 1988). This research explores the use of Statistical Process Control (SPC) charts as a tool to visualize and analyze performance in a decision-making task. The data submitted to control charting was collected in an experiment that explored the effect of order of training or experience in working with alternate display formats. Results for an individual subject as well as a summary for one of the four experimental groups are discussed. Suggestions for further applications of these techniques are offered.

    CONSUMER PRODUCTS: Alternative Format

    Hands-On Answers on Personal Digital Assistants, Part I [Alternative Format] BIB --
      Elizabeth B. N. Sanders; A John P. Chin (Chairs)

    CONSUMER PRODUCTS: User Interface Design [Lecture]

    Handheld Computer Terminals: Starting Off Right the First Time BIBA 355-359
      Karen S. Wilson; Thomas R. Callaghan
    Advances in miniaturization and wireless communications are providing the computer industry with the impetus to design handheld, portable computer terminals. Until enough research and experience evolves from handheld terminals to build a literature on design factors and to develop design guidelines and standards that would provide starting points for product design, the human factors community must rely on its user-centered design approach of designing, prototyping, and testing to ensure a safe and usable form factor for such terminals. The methodology that was used in establishing the design criteria for such a terminal included literature research, focus groups with potential users, contextual field research, expert testimony, and primary laboratory research, including a grasp analysis and screen viewability, data entry, signature capture, and holsterability testing. The user-centered design process described here provided the information required to establish the basic design criteria that would assure user safety and task efficiency. It also revealed informational needs for the human factors community involved in the development of handheld computer terminals.
    Design of a Menu for Small Displays Presenting a Single Item at a Time BIBA 360-364
      Sung H. Han; Jiyoung Kwahk
    Electronic consumer products such as desktop laser printers, facsimiles, copiers, etc., which have a small visual display panel are ubiquitous. They are characterized by presenting only a single menu item at a time which is usually organized in a hierarchical tree structure. Since users see only a single line information on the display and use them infrequently, the optimal menu design may be different from that of an ordinary computer display. An experiment was conducted to examine variables for designing the optimal menu on a single line display. Prototypes were developed to simulate the user interfaces of several menu structures. The results showed that the search time on the small display was approximately three times longer than that on the ordinary computer display. User experience affected significantly the search performance and a menu structure with depth 2 was found to be the optimal for infrequent users. Based on the results of the experiment, human factors guidelines for designing a menu on a single line display were suggested.
    Design of Simplified Television Remote Controls: A Case for Behavioral and Emotional Usability BIBA 365-369
      Robert J. Logan; Sheila R. Augaitis; Thomas Renk
    Remote controls are part of everyday life. Unfortunately, the experience of using a remote is not always pleasurable. This research documents the process of developing multiple remote control concepts that are ergonomic and enjoyable to use. As part of the design process, we researched design concepts with 147 consumers in three cities. The research yielded design-specific data, but also provided insight to some general consumer trends in remote usage and preference for children and adults. This research also suggests that an expanded definition of usability may be required for certain product categories such as consumer electronics. Central to this expanded definition are the concepts of behavioral and emotional usability. Behavioral usability refers to the traditional work related definition of usability. Emotional usability refers to additional needs, such as entertainment or enjoyment, that enhance the product usage experience.
    User Interfaces for Different Cultures: A Case Study BIBA 370-373
      M. A. Hartevelt; E. P. G. van Vianen
    The paper presents a case study carried out to investigate cultural differences between Japanese and European users in their use of television user interfaces. The paper describes the methods used and presents the most interesting results of this case study.

    CONSUMER PRODUCTS: Labels and Warnings [Lecture]

    Incidental Exposure to Rotating Warnings on Alcoholic Beverage Labels BIBA 374-378
      Michael S. Wogalter; John W. Brelsford
    No previous research has been published specifically aimed at determining the effectiveness of rotating warnings (as is required in the government-mandated cigarette warnings). This issue has become relevant because decisions may be made with respect to rotating warnings in print and broadcast alcoholic beverage advertisements, and perhaps for labels and ads for other products as well. The present study used 80 participants in a controlled incidental-exposure laboratory experiment. The effect of the current government warning label for alcoholic beverages was compared to a 5-warning and a 10-warning rotating scheme as well as a no-warning control condition. The study was disguised as marketing research where participants were incidentally exposed to the warnings while evaluating a set of alcoholic beverage labels. The dependent measure was performance on a test of alcohol facts and hazards. Findings show that the present single government warning label is inadequate compared to multiple (rotated) warnings. The 10-warning condition produced higher test scores than either the single government warning or no-warning conditions. Overall, the 5-warning condition produced intermediate levels of knowledge. Also, four exposures produced greater specific warning content knowledge than either two or no exposures. The results suggest that rotating multiple warnings are a better means of communicating facts and hazards than a single repeated warning of limited content. Policy implications are discussed.
    Differences in Behavioral Compliance as a Function of Warning Color BIBA 379-383
      Curt C. Braun; Brian Greeno; N. Clayton Silver
    A body of literature asserts color's influence on display preference, cognition, behavior, and performance. Although these results have clear implications for the design of consumer product warnings, color has been disproportionately underrepresented in warnings research. The present study examined the effect of color on compliance with printed warnings. Sixty-five undergraduates interacted with a pool water test kit and a two-part adhesive. The warning on each product was factorial for color (i.e., red, green, and black) and was constant for content. Participants indicated a higher likelihood of injury associated with products printed in red than green or black. Behavioral compliance was assessed by indicating if subjects donned protective gloves as directed by the warning. The data indicated that warnings printed in red resulted in a higher proportion of compliant behavior than green and black combined.
    Enchancing the Perceived Readability of Pharmaceutical Container Labels and Warnings: The Use of Alternative Designs and Pictorials BIBA 384-388
      Michael J. Kalsher; Michael S. Wogalter; Shari Pucci; Bernadette M. Racicot
    The appropriate use of pharmaceuticals, as well as their hazards, are not commonly known to most people. In fact, the only information available to consumers is usually the material found on the product label. Unfortunately, for some consumers this method of communicating instructions and risks may be ineffective, and potentially dangerous. People may have difficulty with the labels because the print on the label is too small for them to read. Two alternative (tag and fold-out) designs were developed to increase the available surface area for information printed on a fictitious prescription drug label. The alternative label designs were compared to a standard control label. The presence versus the absence of pictorials visually depicting several instructions and warnings was also examined. Participants rated the labels on ease of reading the labels, likelihood of noticing the warnings, likelihood of reading the warnings, preference for each of the labels, and likelihood that they would recommend each label for use by a friend or family member. The results showed that participants (n = 84) preferred the alternative label designs, especially the tag labels, and those with illustrative pictorials. Implications of these results and recommendations for future research in this area are discussed.
    Product Label List Format: Effects of Item Arrangement and Completeness on Comparison Time and Accuracy BIBA 389-393
      Michael S. Wogalter; Michael J. Kalsher
    This research examined the influence of two factors on the ease of gaining information from item lists: the order and completeness of the items displayed. Food nutrition labels served as the vehicle to test the manipulated lists on comparison time and accuracy performance measures. Four booklets, each containing 12 pairs of nutrient labels, were constructed in which the listed items were: (1) either arranged in a standard order or in a random order, and (2) either had a complete set of nutrients (including nutrients not present in the product) or a partial set of nutrients (excluding nutrients with zero or near-zero amounts in the product). Thirty-two participants were instructed to assume that their physician has told them to increase their intake of three specific nutrients and decrease their intake of three other nutrients. One label of each pair contained a higher level of one nutrient that should be increased or a lower level of one nutrient that should be decreased. Participants were to determine which of the two labels would be better given the prescribed diet. Time and accuracy measures were collected. Participants made significantly faster judgments for nutrients arranged in a standard order than for nutrients arranged in a random order. For all conditions, the error rate was low. An interaction indicated that labels with a complete set of nutrients in a standard order produced fewer errors than (a) labels in a standard order with some nutrients missing or (b) labels with a complete set of nutrients in a random order. Implications of making lists compatible with expectations are described.


    I'm Graduating, Now What? A Comparison of Work in Academics, Consulting, Government, Industrial Research, and Industrial Development BIBA 394-398
      Ronald G. Shapiro; Barry Beith; Joseph H. Goldberg; Joe Hale; John F. ("Jeff") Kelley
    The purpose of this panel is to familiarize students and faculty members with what Human Factors Professionals do in a variety of settings including academics (Joe Goldberg), consulting (Barry Beith), government (Joe Hale), industrial research (Jeff Kelley), and industrial development (Ron Shapiro). This panel compares some of the advantages and disadvantages of various career options to help student determine where they best fit, and to help them prepare for interviews.
       This panel focuses upon addressing basic questions to familiarize students with a variety of working environments: academics, consulting, government, industrial research, and industrial development.
       There are seven key questions that each of the panelists addresses:
  • What are typical job responsibilities?
  • What are the rewards?
  • What are the frustrations?
  • What skills does one need?
  • How do you make contact with people?
  • What is an interview like?
  • What contributes to success/failure?
  • EDUCATORS' PROFESSIONAL: Issues in Training and Learning Human Factors [Lecture]

    Electronic Resources for Human Factors and Ergonomics Education: Lessons from Human-Computer Interaction BIBAK 399-403
      Gary Perlman
    I describe four electronic educational resources available via computer networks and electronic mail:
  • (1) a curriculum module on user interface development;
  • (2) a bibliography on human-computer interaction;
  • (3) a description of courses and curricula in human-computer interaction, and
  • (4) a survey of educational opportunities in human-computer interaction. For each of these, I discuss:
  • (1) why the resource was created,
  • (2) how the information was gathered,
  • (3) what information has been gathered,
  • (4) how to access the information,
  • (5) how it has been used in HCI education, and
  • (6) how the information (or information like it) can be applied to Human
        Factors and Ergonomics (HF/E) education. I conclude with recommendations for the modernization of HF/E information infrastructure.
    Keywords: Educational resources, Internet network access, Electronic publication/dissemination
  • Ethical Issues Related to the Use of Humans in Human Factors and Ergonomics BIBA 404-408
      William F. Moroney
    As professionals, we must be aware of our ethical responsibilities when engaged in research and testing. The purpose of this paper is threefold: 1) to increase the reader's awareness of some of the issues specific to our discipline, 2) to provide some guidelines and references regarding the use of human subjects, and 3) to increase the dialog in this critical area. The material discussed focuses on Federal Regulations related to the protection of human subjects. The changing role of the human subject from "research material" to "participant partners" is also discussed.
    Integrated Job Design in the Introductory Human Factors Course BIBA 409-411
      Andris Freivalds; Joseph H. Goldberg
    Two different workstations are being utilized in the introductory human factors course: a workstation appropriate for typical blue-collar assembly work and a workstation appropriate for white-collar computer driven work. The white-collar workstation simulates a modern computer driven office job, with different factors influencing its productivity, such as speed, accuracy, noise, illumination, etc. The blue-collar workstation is centered around a typical carburetor assembly process found in the U.S. automotive industry. This is especially appropriate 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 examine various tool parameters and are 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. Such an approach allows for the integration of traditional industrial engineering concepts with more modern human factors theory, for the 'solving' of open-ended problems and provides students with real-world applications.
    Applying Human Factors to Classroom Visual Aids BIBA 412-416
      Susan J. Shapiro
    Transparencies, slides, and computer based displays are common visual aids used in classroom presentations. This paper will outline the use of principles which improve the effectiveness of these visual aids
       General principles discussed include: Organizing material, clarifying material and enhancing encoding. Gestalt principles such as simplicity, similarity, proximity, and continuation, appropriate text size and font, effective use of color and other attention getting cues, and appropriate contrast and glare reduction are considered.


    Educating People with Disabilities BIBA 417
      A. Mital; S. Deivanayagam; D. Malzahn; S. Wiker; G. C. Vanderheiden; A. Freivalds
    Accommodating individuals with disabilities in the workplace is a rapidly growing concern. Furthermore, those who are functionally impaired are in a dire need of assistance. In a classroom, the main function of a student is to learn. Learning is facilitated by an instructor's lectures, writings on the board, use of audiovisuals, etc. Generally, it is presumed that students do not have any common functional impairments (visual, auditory, etc.) and, therefore, no special effort is made to accommodate those who may have such impairments. Obviously, the learning of a legally-blind student or one who has impaired hearing, for example, will be compromised if no assistance is provided. Then there are issues such as providing reading materials for the blind (college catalogues, lecture notes, etc., in braille?). What should be done?
       The purpose of this panel discussion is to, in general, address and discuss the issues involved in educating people with disabilities, particularly those that are not very obvious or visible (ex., wheelchair confinement). How should university campuses resolve this problem in this age of dwindling resources? Sensitive issues, such as "Needs of the many versus the needs of the few?" and "What responsibility do we have to the few that really need such assistance?", also need to be resolved.


    The Work of the ANSI/HFES 100 VDT Standards Committee: An Overview BIB --
      Robert J. Beaton; Michael J. O'Neill; Rodney Don Williams; Wanda J. Smith; Karl H. E. Kroemer; Alan Hedge

    ENVIRONMENTAL DESIGN: A Systems Approach to Preventing Work-Related Musculoskeletal Disorders in VDT Work [Symposium]

    A Systems Approach to Preventing Work-Related Musculoskeletal Disorders in VDT Work BIBA 418
      Hal W. Hendrick; Michael J. O'Neill; Michelle M. Robertson; Ogden, Jr. Brown
    Work-related musculoskeletal disorders (WMSDs) are not a new ergonomic issue. In fact, WMSDs related to manual materials handling have been recognized as a major ergonomics issue since the late 1940's. What is new is the widespread increase in WMSDs as a result of the introduction of video display terminals (VDTs). Unlike many manual materials handling situations, VDT related WMSDs do not appear readily correctable solely by conventional workstation design ergonomics.
       This symposium proposes a systems approach to the problem. It begins by presenting a macroergonomic approach to work system and job design, addressing specific job characteristics identified with WMSDs in the literature.
       The second paper deals with the critical issues to address in ergonomically designing the work environment; and providing environmental control by the user to further enhance desirable job characteristics and reduce WMSDs.
       The third presentation outlines the critical elements to incorporate in programs for training VDT operators on procedures for preventing WMSDs.
       The final paper discusses utilizing employee participation in accomplishing the tasks identified in the first three papers.
       The symposium concludes that only through such a systems approach can real progress be made in reducing VDT operator WMSDs.
    Work System and Job Design Factors in Preventing WMSDs in VDT Operators BIBA 419-423
      Hal W. Hendrick
    Recent research is reviewed which indicates conventional work station design ergonomics is insufficient, by itself, to prevent WMSDs in typical VDT jobs; and that work system design and related psychosocial variables appear critical. Three common system design practices are cited as the basis for the widespread poor design of VDT work systems and jobs. Macroergonomics is proposed as a work system and job design approach that circumvents the deficiencies of these three common design practices. Specific job design factors from the literature are identified.
    Environmental Design and Worker Control for Preventing WMSDs BIBA 424-428
      Michael J. O'Neill
    Environmental control is defined as the degree to which the organization, group or individual can exert control over the physical environment as part of the process of accomplishing mission or job-related goals. This paper proposes a model which suggests that control over the physical environment may also be a means of reducing stress and work related musculoskeletal disorders (WMSDs) in office workers. Control is thought to be related to both performance and WMSD issues. The model uses systemic framework, placing the individual within the larger context of the workstations workspace, and the overall facility. The potential for control exists from the macro (facility level) to the micro (individual workstation) environmental scale. Control can be exercised through several mechanisms, including: flexibility of initial building design (reusability, ability to expand or downsize), overall layout of the work group environment (group ability to self-manage and reconfigure space) and flexibility of workstation features (such as task lighting, storage, shelving, work surface height, enclosure, VDT, HVAC).
    Designing VDT Operator Training Programs for Preventing Work Related Musculoskeletal Disorders BIBA 429-433
      Michelle M. Robertson
    A systems approach is essential in addressing work related musculoskeletal disorders associated with VDT work. One integral component in the systems methodology is that of designing, developing and implementing an effective VDT training program. This paper specifically focuses on the importance of a VDT training program, how the training should be comprehensive, and systematically evaluated. Elements of a successful ergonomic VDT training program are described and examples of two successful VDT training programs are given.
    Participatory Ergonomics as a Means of Preventing WMSDs BIBA 434
      Ogden, Jr. Brown
    Participatory ergonomics is a flexible means for the achievement of many diverse goals in turbulent technological environments. It is a macroergonomic approach to the implementation of technology in organizational systems which requires that end-users be highly involved in developing and implementing the technology. The notion of participation offers the promise of tremendous potential gains for the organization, the worker, and even the economic well-being of the greater society.
       Such pervasive and important technological innovations as the use of computers and their concomitant video display terminals can, in spite of their usefulness, lead to many occupational health and safety problems. Cumulative trauma disorders appear to be an associated dysfunction in modern industry, and effective health and safety solutions to many of these problems are highly important, both to the organization and especially to the people in it. It is proposed that the use of participation and worker involvement in the solution of such problems is a powerful and promising tool.
       There is no one best way to employ worker participation. It is contingent upon the nature of the problem itself, the work system, the job design presently in place, the environment in which the work is done, the training of the worker, and a myriad of other variables.
       From the available empirical evidence, a participation topology is postulated. The successful implementation of participatory ergonomics and other participatory arrangements requires the empowerment and enablement of people to make decisions concerning their work and to implement and evaluate them.
       Several participatory approaches to worker involvement are presented which address work system and job design factors, design of the work environment, and training of VDT operators. These approaches are discussed in the context of a systems approach to the prevention of WMSDs.
       The reduction and/or prevention of cumulative trauma disorders such as work-related musculoskeletal disorders is a matter of great concern in modern organizational life, both from the point of view of productivity concerns and also from that of the humanization of work. The solution of occupational health and safety problems will not only lead to increased organizational effectiveness, but should help provide for a far better realization of human potential.


    A Viewpoint on Professional Conduct for Ergonomic Experts in Forensics BIBA 435-437
      Leighton L. Smith; Melvin H. Rudov; Thomas Dingus; Jake Pauls; Gary T. Staffo
    This panel session explores the paradigm of professional conduct for ergonomic experts in the practice of forensics. A hypothesis of conduct is offered as a candidate guideline for professional conduct. This hypothesis is based on basic professionalism principles and has been adapted on the basis of observed experiences in the field, comments from other practicing professionals, and in the context of previous draft "codes" of professional conduct for human factors professionals and also for ergonomic forensics practitioners. The panelist contributions to this session range from a discussion of the need for and merits of a standard of professional conduct, to institutionalization of standards or codes of conduct, to the breadth and scope of professional involvement in forensics, to the mechanics of the actual practice of professional ergonomic forensics, to a comparative perspective from the related discipline of safety.

    FORENSICS PROFESSIONAL: Problems with User Information [Lecture]

    The Understandability of Legal Documents: Are They Adequate? BIBA 438-442
      Julie E. Howe; Michael S. Wogalter
    Citizens are frequently asked to make commitments by signing contracts and legal documents that frequently contain phraseology and jargon (sometimes called legalese) that highly-educated citizens often do not understand. In recent years, human factors professionals have become intimately concerned with the design of product-related documentation and safety communications (e.g., warnings), and through research have offered ways to improve these materials. However, there is apparently no human factors research on the design and evaluation of legal contracts and other similar documents. The purpose of the present research was to begin to assess some of the factors related to people's reading and understanding of legal documents. Study 1 examined the types of legal documents that people sign, how often they sign them, how carefully they read them, and whether they understand them. Ninety-two individuals were asked to complete a survey addressing these issues. While it was reported that the contracts were read moderately carefully and were understood moderately well, the levels were not as high as one would expect given the importance of the documents and the education level of the participants in this study (who had, on average, approximately two years of college). Also, 96% of the sample believed that legal documents could be improved and provided specific suggestions on how this might be accomplished. In Study 2, 32 participants rated the set of potential improvements to legal documents that had been suggested by Study 1's participants. The results confirmed the first study's pattern of findings. Implications for average citizens' lack of comprehension of contracts and other legal documents are discussed with a specific focus on the role research might have on their improvement.
    Safety Considerations in Bicycle Motocross Racing: A Case Study BIBA 443-446
      Patricia L. Jackson; H. Harvey Cohen
    This paper presents a case study and literature review on the subject of bicycle moto-cross racing. The case involves a 17 year old male who was severely injured as a result of crashing into a jump during a BMX race. The young man suffered a broken neck and is now a quadriplegic. The paper examines both medical and popular literature on BMX racing and safety. Questions posed include: why no studies have been done to determine the risk of injury in BMX racing; why there are no national databases on BMX injury statistics; and what role the image of BMX in popular magazines plays in promoting or dismissing safety in BMX racing? We found very little information available on the subject of BMX. What information we did locate was inconsistent regarding rules of safety and sportsmanship, risk of injury, and opinion on the safeness of BMX racing. We recommend the following practices as ways to increase safety in the sport: multiple track levels designed for different skill levels; supervised training programs with practice areas for experimenting with new maneuvers; and lessons in tumbling and falling safely to minimize the risk of injuries. We also suggest that studies and databases need to be compiled to consistently evaluate the risk of serious injury in BMX racing.
    Availability of Owners' Manuals for 'Second-Hand' Consumer Products BIBA 447-450
      Michael S. Wogalter; Robin C. Baneth
    This research concerns the availability of owner's manuals for second-hand (used or resold) consumer products. One hundred people were approached in a shopping center mall and asked various consumer-oriented questions including: (a) whether they have ever purchased new and/or used 20 common consumer products (e.g., car, computer, power lawn mower, bicycle, etc.), and if so, whether those products came with an owner's manual or an instruction sheet when purchased; (b) whether they had personally sold any of the products, and if so, whether they transferred the owner's manual to the new owner; and (c) how much they would pay for the owner's manuals for each product assuming they had to purchase it separately. Also, they gave 9-point ratings on the products' familiarity, hazard level, and difficulty of use. The survey included several other questions including asking participants how they store their manuals, and for them to estimate the search time to find them. The findings show that while owner's manuals for some used-products are frequently transferred to new owners, others are not. In the latter cases, lack of owner's manual availability means that certain kinds of important safety information may not reach consumers -- despite consumers wanting the information and the fact that manufacturers' included it with the product at its first sale. The results also indicate that people want access to owner's manuals for second-hand product. Participants agreed that including the owner's manual would help the sale of used products and that they were willing to pay extra for one (particularly for difficult-to-use products). These results suggest that manufacturers ought to address ways that would make it more likely that consumers retain the owner's manual and transfer it to subsequent owners at later resale, and provide consumers with convenient ways that they can request a replacement copy should the original manual become inaccessible.
    Influence on Ratings of Risk for Consumer Products BIBA 451-455
      S. David Leonard; J. Bradley Cummings
    Previous studies have suggested many persons do not know the meanings of many terms commonly used as stand alone descriptions of hazards. Studies (Leonard & Digby, 1992; Leonard & Hill, 1993) have shown that the same hazard description, for example flammable, associated with different products resulted in very different perceptions of risk. The present study eliminated anchoring effects that may have resulted from using separate categories by combining 13 different products into a single set for both rating and ranking. The results were consonant with previous findings in that a low correlation between subjective impressions and physical characteristics was found. Subjects in a second study who received a demonstration of some of the products' flammability significantly changed their ratings. The discussion involved consideration of how cognitive information may be developed.


    PRESIDENT'S FORUM: Discussion of Perspectives on Marketing of Human Factors in the Federal Government BIB --
      Thomas B. Malone; Mark Hofmann; William C. Howell; Richard W. Pew

    GENERAL SESSIONS: Issues in Automobile Transportation [Lecture]

    Risk Perception Issues in the Use of Motorized Shoulder Belt/Manual Lap Belt Systems BIBA 456-460
      David R. Lovvoll; Kenneth R. Laughery; Michael S. Wogalter; Stephanie A. Terry
    Two experiments employed surveys to address seat belt experience and use as well as perceptions of risk associated with various seat belt configurations. In Experiment 1, a questionnaire was administered to two samples: 104 students at the University of Houston and 162 volunteers at a shopping mall in Raleigh, North Carolina. Of primary interest was the use of manual lap belts in motorized shoulder belt systems and reasons for their use or non use. Results showed that compared to manual three point belts, usage rates for manual lap belts in the motorized system were lower. Forgetting and traveling a short distance were frequency cited as reasons for not fastening belts. Estimates of fatalities in a head-on collision scenario indicated lap belts and shoulder belts were perceived to provide equal protection. In Experiment 2, 147 students at the University of Houston completed a follow-up questionnaire. Usage patterns were virtually the same as in Experiment 1. Estimates of likelihood to use lap belts after viewing six different warnings about seat belt use showed warnings containing more explicit hazard information were likely to lead to higher use rates.
    Human Factors Studies to Investigate Driver Behavior under In-Vehicle Information Systems: An Interactive Microcomputer Simulation Approach BIBA 461-465
      Jeffrey L. Adler; Michael J. Kalsher
    In-vehicle traveler information systems are being designed to provide drivers with real-time route guidance and/or traffic advisory information. It is expected that these Advanced Traveler Information Systems (ATIS) technologies will have a major impact on travel efficiency by assisting drivers to make better real-time route choices in response to changing network conditions. There is not yet full knowledge as to the impacts that route guidance and traffic advisory systems will have on driver behavior. This paper presents preliminary results from a human factors experiment to investigate the effects of traffic advisory and route guidance information on enroute behavior and travel performance. An interactive microcomputer simulation was used for data collection. The study suggests that both drivers' route choice efficiency and understanding of network conditions can be improved with access to real-time traffic advisory and route guidance information.
    Utility Assessment of Side Object Detection Systems for Heavy Trucks BIBA 466-475
      Elizabeth N. Mazzae; W. Riley Garrott; Anthony J. Cacioppo
    Side object detection systems (SODS) alert drivers to the presence of traffic alongside their vehicle within a defined detection zone. Their intent is to reduce lane changing and merging collisions. The effect of right SODS on the safety related behavior of commercial vehicle drivers was examined in this study.
       Eight subjects drove a tractor-semitrailer equipped with four different sets of right SODS or mirrors. Subjects were tested with two right SODS (a radar-based system, and an ultrasonic-based system), a fender-mounted convex mirror, and, for comparison, standard side view mirrors. For each case, subjects drove the test vehicle through a set route for one day. The effect of these systems on driver behavior and the extent to which safety may be improved by implementing SODS were assessed based upon the correctness of responses and verbal response times to Right Clear questions, and upon subject glance fixations and durations. A debriefing questionnaire was used to acquire subjects' opinions about the SODS.
       Driver performance with SODS was not significantly improved over that observed with standard side view mirrors. Analysis of the correctness of responses to Right Clear questions showed that subjects' accuracy in assessing the traffic situation along the right side of the vehicle was not improved by the SODS, but was improved by the fender-mounted convex mirror. Verbal response times to Right Clear questions were significantly lower with the SODS and fender-mounted convex mirror than with standard mirrors. This difference may have resulted from a learning effect caused by presenting the standard mirrors first to each subject. Glance data showed that subjects only sometimes visually sampled the SODS displays. Responses to debriefing questionnaires indicated that subjects were receptive to the concept of SODS and very positive about the fender-mounted convex mirror. However, if SODS are to offer significant safety benefits in the future, more work is needed to refine their performance and design.


    Recent Advances in Human Factors in Manufacturing BIBA 476-480
      Anand K. Gramopadhye; Ram R. Bishu; William B. Rouse; Waldemar Karwowski; Colin G. Drury; Edward L. Cochran
    The combined effects of automation and global competition have changed the manufacturing environment considerably. The change is from a traditional product or process oriented manufacturing to a fully automated or semi-automated manufacturing environment, producing limited quantities of a large range of products. Inexpensive and unlimited computing power has been the single cause for these changes.
       What impact have these changes had on human factors/ergonomics professionals? Does a problem really exist and is its existence recognized in affected areas by other people, those not involved with human factors? Have human factors professionals taken proactive approaches to these changes? What are the new techniques available to the human factors professionals in this application area? This panel will address some of the issues and concerns in this area.

    GENERAL SESSIONS: Report of the Technical Advisory Group [Symposium]

    Report of the Technical Advisory Group BIB --
      James P. Jenkins
    Information Infrastructure Technology and Applications BIB --
      James P. Jenkins
    Virtual Reality and Telepresence BIB --
      Thomas B. Sheridan
    Intelligent Vehicle/Highway System BIB --
      Richard F. Pain
    Advanced Medical Instrumentation BIB --
      Marilyn Sue Bogner

    GENERAL SESSIONS: Displays and Vision Potpourri [Lecture]

    A Direct Perception Interface for Nuclear Power Plants BIBA 481-485
      Neville Moray; John Lee; Kim J. Vicente; Barclay G. Jones; Jens Rasmussen
    Following the suggestions of Beltracchi (1987) a direct perception interface for the thermal hydraulic systems of a pressurized water nuclear power reactor (PWR) was developed. It presents operators with an animated graphic of the Rankine heat cycle describing the functional relations of steam generation in a PWR. The ability of students of thermal and nuclear systems to recall system states, and detect and diagnose nine transients was compared to that of experienced nuclear power plant operators. The results were compared to a display representing traditional analog meters. The direct perception interface supported better diagnostic performance, but did not improve memory for quantitative information. Problems in evaluating such displays are discussed, in particular concerning choice of scenarios, and investigation of failure modes of advanced displays.
    Comparing Ecologically Constrained and Conventional Displays in Control of a Simple Steam Plant BIBA 486-490
      Carl Edlund; Michael Lewis
    Graphical User Interfaces (GUIs) are becoming increasingly common for application software in process control. Conventional interfaces display the states of a system without conveying the constraints which drastically reduce the evolutions which must be considered. Our model resolves this difficulty by presenting system parameters in the context of ecological constraints mirroring those of the underlying process. A simulation of a simple steam plant with five different GUIs was used. The displays were a conventional Dials display, a Mimic display, an Object display, a Seesaw analogue, and a Fluid-tank analogue. Poor over-all performance in maintaining specified values was found for the Seesaw and the Object displays. The Dials and the Mimic displays performed similarly but with greater accuracy. The best control was observed in the experimental Fluid-Tanks display. These Findings are consistent with our hypotheses.
    A Double Edge Sword: Compensatory Behavior in Coping with System Malfunctions BIBA 491-495
      Daniel Gopher; Maya Weil; Ido Erev
    Malfunctions and minor technical problems in system operation are not a rare event when humans interact with engineering systems. When a problem is detected, the system should, in principle, be halted and repaired. Often, however, operators decide to continue their work and adopt alternative modes of behavior that bypass or compensate for the malfunctions. We label this type of responses "compensatory behaviors". They are adopted because the operator judges them to be less costly than the costs involved in stopping and repairing the system. Twenty Subjects, had four sessions of training, with a simulated filling work station in a chemical plant, where 8 simultaneous tanks had to be filled with lethal solutions. Malfunctions in the automatic filling regulator of one of the tanks, occurred intermittently, resulting in two types of risks: a high risk failure could explode the entire system at the cost of 200 points; a low risk failure could lead to a defective container, translated to a loss of 10 points. Subjects could resolve to shut down the station for repair at the cost of 100 points, or switch the failed tank to manual and stop the filling when the liquid reached the required volume. Their ultimate goal was to achieve the highest score possible. Results showed significant preference for compensatory behavior over repair, in all stages of skill acquisition and at all levels of potential risk. When adopting compensatory behavior, subjects' decision, attention and main efforts seem to have been exclusively guided by their ability to avoid the occurrence of explosions. The number of explosions was indeed reduced, although not eliminated, with training. At the same time, and in contrast with their belief, subjects slowed down their production rate, had more errors and more defective containers. Thus the total cost of compensatory behavior was higher than the costs of repairing the system. This is the double edge sword of compensatory behavior. The selective focus on direct costs and the neglect of indirect costs, have important implications to decision behavior research and skill acquisition, as well as practical implications to the development of training programs and work procedures.
    Age and Glare Recovery Time for Low-Contrast Stimuli BIBA 496-499
      Frank Schieber
    The purpose of this study was to obtain a rigorous experimental estimate of the time required to recover from the deleterious effects of glare. Low contrast test stimuli were employed to increase the potential sensitivity of the procedure. Multiple age groups were sampled since susceptibility to glare effects is known to increase with advancing years. Glare recovery time assessments were collected from 12 young, 12 middle-aged and 16 older adults. Subjects were presented with 10 sec exposures to an intense glare source under highly controlled experimental conditions. Upon the offset of the glare exposure period, the time required to regain sensitivity for low contrast test stimuli was measured. Relative to their younger counterparts, older subjects required 3-times longer to recover from glare exposure. These findings suggest that the dynamic components of glare effects must be considered when designing environments -- especially where older observers are involved.

    GENERAL SESSIONS: General Sessions Potpourri [Lecture]

    Movement Times of Right and Left Handers Using Preferred and Non-Preferred Hands BIBA 500-504
      Errol R. Hoffmann
    The aim of the present work was to quantify the difference in performance of hands when doing tasks of defined difficulty. Results of five experiments are reported in which strongly lateralised subjects performed movement tasks with their preferred and non-preferred hands. These tasks were (i) ballistic movements (ii) Fitts' task (iii) pin-to-hole transfer (iv) Drury tracking task (v) a modified form of the Drury tracking task in which subjects cut paper with scissors. The results showed that in ballistic tasks there was no significant effect of handedness or of hand used. With visually-controlled tasks, where there was considerable control of accuracy required, the preferred hand generally performed better than the non-preferred hand. There was however no significant difference, in any of the tests, between right and left handers when using their preferred hands. Left handers, in some tasks, performed better with their non-preferred hands than did right handed persons using the non-preferred hand.
    Auditory Monitoring of Up to Eight Simultaneous Sources BIBA 505-509
      Dennis J. Folds; Jeffrey M. Gerth
    The present research examined visual and auditory monitoring of independent, concurrent sources. Subjects monitored from one to eight concurrent visual indicators for the occurrence of a "launch" event. Five between-groups conditions were studied: a visual-only group, plus four audiovisual groups that differed in the amount of information provided over the auditory channel. Accuracy scores were very high for all groups. Response times showed an overall increase with display density (number of concurrent sources). A significant group x density interaction revealed an advantage of one of the audiovisual conditions compared to the visual-only group at moderate density levels (5 or 6 concurrent sources), but not at lower or higher density levels. This finding probably indicates the value of an auditory signal to reduce visual search time.
    A Methodology for Investigating Heat Stress Selectivity Effects on Mental Performance BIBA 510-514
      Ioannis Vasmatzidis; Robert E. Schlegel
    This paper outlines a methodology that can be used to investigate the selectivity patterns of heat stress effects. The adopted view is that heat stress causes performance to deteriorate because it depletes attentional resources. The term "selectivity" refers to the extent to which certain individual resource pools (the existence of which is postulated by multiple resource theories) are more susceptible to heat stress effects than others. The methodology consists of plotting performance of two time-shared tasks over time on the Performance Operating Characteristic (POC) space. Manipulating the difficulties of the paired tasks under the same environmental conditions (i.e., temperature level and exposure duration) produces a predictable change of the POC path. In particular, if the heat stress effects are non-selective, the POC path will rotate either clockwise or counter-clockwise depending on the task whose difficulty is increased. On the contrary, if the heat stress effects are selective, increasing the difficulty of a task will have no effect on the orientation of the POC path.
    On Validation BIBA 515-519
      H. Kanis
    In view of the deficient way validation and measurement error are dealt with in Ergonomics/Human Factors research papers, there seems to be much to gain in this multidisciplinary research area. The comparison of practicalities in technical and in social research, which are seen as the main constituents of Ergonomics/Human Factors, elucidates the crucial role that instructions to subjects may play in the emergence of bias as a consequence of the involvement of human beings as part of the research object. Instead of letting validation degenerate into jargon, a framework for measurement criteria is presented. This framework may help to change validation from a defensive ceremony, circling around isolated observations, into a constructive endeavour aimed at general insights into the consequences of human involved research.

    GENERAL SESSIONS: Human Factors and Design Factors: Two Sides of the Same Coin? Part I [Symposium]

    Human Factors and Design Factors: Two Sides of the Same Coin? BIBA 520
      Thomas J. Smith
    Since its emergence, the field of human factors has been engaged in an ongoing debate regarding the scientific essence of the discipline. Many observers believe that the crux of the debate centers upon the link between human factors and design factors, or performance-design interaction. Presenters in this symposium offer a series of perspectives on this theme, in relation to: (1) emphasis on behavioral considerations in design of complex automated systems (Meister); (2) emphasis on contextual specificity in teaching of design (Moray); (3) an ecological analysis of human-environment interaction as an integrated system (Flach); and (4) core principles of human factors science centered upon performance-design interaction (Smith).
       The rationale for this symposium rests upon the widespread belief that the relationship between performance and design represents the defining issue of human factors science. That is, through its focus on functional integration of performance and design, human factors departs from the traditional dissected treatment of these phenomena by psychology and engineering. Therefore, the status of human factors science as an integral discipline may be considered to rest upon the answer to the question of how and why human behavior and performance vary in relation to design factors in the performance environment. Papers presented in this symposium provide insight into this question from a number of different perspectives.
    Behavioral Design of Automated Systems BIBA 521-525
      David Meister
    Behavioral design of computerized systems must account for the operator's changed role: from controller, to monitor, supervisor, and troubleshooter. Design guidelines will replace present fixed verbal prescriptions with mathematical curves relating relevant variables.
    "De Maximus Non Curat Lex," or, How Context Reduces Science to Art in the Practice of Human Factors BIBA 526-530
      Neville Moray
    Frequently claims are made that what the discipline of human factors and ergonomics needs are better and more detailed data bases which can be used by designers as "look up" tables to specify the properties of human beings. Several of these already exist but they seem not to be satisfactory. The experience of teaching user centered design has convinced the author that the problem lies not in the absence of appropriate data tables for designers, but in the nature of the systems we design. Unlike many other engineering disciplines human factors is extremely sensitive to context. The result is that there are no such things as context free laws in applied psychology, and hence the value of data bases and tables is restricted to certain fairly basic ergonomic problems. It is moreover not merely in small details that laws do not apply -- hence the title of this paper. Increasingly the nature of advanced systems renders such data bases of little value unless we can develop equivalent data bases which describe context, not merely the properties of humans.
    Ruminations on Mind, Matter, and What Matters BIBA 531-535
      John M. Flach
    If psychology is the science of "mind" and physics is the science of "matter", then human factors is the science of "what matters". This claim is more than a simple observation about the scope of human factors (i.e., that it's scope overlaps both with psychology and physics). Rather, I will argue that the science of "what matters" requires an entirely different ontology than those which have traditionally provided the basis for psychology and physics. Two constructs will be central in the ontology of "what matters" -- affordance and information.
    Core Principles of Human Factors Science BIBA 536-540
      Thomas J. Smith
    This report introduces three core principles that define human factors science, and summarizes conceptual and empirical evidence in support of their validity. The principles are: (1) performance and design are interdependent; (2) the unit of analysis is the human-machine system; and (3) tailor design to the control capabilities of behavior.


    Human Factors and Design Factors: Two Sides of the Same Coin? BIBA 541-543
      Thomas J. Smith; John M. Flach; David Meister; Neville Moray
    This panel accompanies the symposium with the same title; the panelists are the symposium presenters. The rationale for offering both a symposium and a panel on the same topic rests upon the following considerations: (1) the nature and extent of interdependence between performance and design factors represents a defining issue for human factors science; and (2) the symposium and the panel together provide a comprehensive forum for addressing the topic, inasmuch as the symposium allows the presenters to offer their perspectives on the topic, and the panel facilitates audience input into the discussion.

    INDUSTRIAL ERGONOMICS: Hand and Wrist Ergonomics I [Lecture]

    A Study of the Effect of a "Resting Splint" on Peak Grip Strength BIBA 544-548
      Graciela Perez-Balke; Bryan O. Buchholz
    The purpose of this research was to study the effect of a resting wrist splint on the change in peak power grip strength (PGS) as compared with bare handed PGS, and to investigate the role of hand morphology on the results. Ninety-six subjects were tested for (PGS) with a Jamar Dynamometer under two conditions: with and without a resting splint. The results showed that PGS decreased by an average of 13.71% (1.35 SE) while subjects wore the wrist splint as compared with the bare handed PGS. A paired t-test was performed on this difference and found to be significant (p<.0005). Female subjects (N = 44) experienced a two-fold greater percent decrease in their PGS (18.52%, 1.49 SE) than male subjects (9.97z, 1.96 SE). The results of this study suggest that PGS is attenuated with the use of a wrist splint, however none of the anthropometric measurements taken of the hand and wrist proved to be correlated with the dependent variables, change and & percent change in PGS. Correlational analysis found that the independent variables: sex, hand span, wrist circumference, and hand length had correlations greater than .5 with both bare and splinted PGS. These variables were entered into a regression analysis and yielded models for the dependent variables, bare and splinted PGS, with R = .5975 and .5835, respectively. An ANOVA, however, revealed that sex and hand length were the only significant independant variables (p<.001 and p<.05, respectively). Qualitatively, subjects complained that the metal bar of the splint decreased their ability to grip the dynamometer. In some cases, subjects reported discomfort while gripping with a splinted wrist. This combination of obstruction, discomfort and force attenuation may decrease the amount of force that workers are able to apply during work activities. Hand morphology failed to identify workers who might improve hand grip with the use of a wrist splint. The results of this study have important implications for the use of a wrist splint while performing work activities that require the use of a power grip.
    Evaluation of Grip Force Exertions in Dynamic Manual Work BIBA 549-553
      Katharyn A. Grant
    An obstacle to the development of guidelines for reducing forceful hand movements is that manual force is not easily measured or estimated at the worksite, especially during highly dynamic activities. Grip force requirements during manual work are dependent not only on object weight, but also on the surface characteristics of the object and the task dynamics. In theory, it is possible to predict grip force requirements for manual tasks using Newtonian laws of physics; however few researchers have attempted to measure grip force during dynamic work, much less to compare actual grip force values to predicted levels. Therefore, a laboratory experiment was conducted to examine grip force exertions during two simulated industrial tasks. In each task, participants repetitively grasped and moved aluminum handles against varying levels of weight or resistance. Grip force was measured using a strain gauge mounted inside the handles. Results indicate that grip force varied continuously throughout each work cycle in response to changes in the motion of the hand/handle. The pattern of variation was consistent between subjects and could be approximated by a sinusoidal model. Greater interindividual variation in grip force exertion was observed when the task allowed greater flexibility in selecting a movement strategy. The results also indicate that subjects are more likely to "overshoot" the necessary grip force (i.e., apply more force than needed) at the initiation of movement, especially at lower weight levels. This study demonstrates that it is possible to predict variations in grip force during dynamic work, although further refinements in the procedure are needed. Use of modelling techniques will enable industrial designers to better estimate grip force requirements and to identify design strategies that will reduce the risk of musculoskeletal injury to the worker.
    Effects of Grip Span, Wrist Position, Hand and Gender on Grip Strength BIBA 554-558
      B. Ramakrishnan; Lisa A. Bronkema; M. Susan Hallbeck
    Extensive literature is available which has examined the effects of grip span, wrist position, hand, gender, and anthropometric dimensions on grasp strength, but none have looked at all the factors combined. A thorough understanding of the relations between these various factors would help minimize workplace risks and improve safety. Thus, a study was performed to relate these factors. Twenty subjects (10 male and 10 female) performed maximal exertions with both hands in three wrist positions (45° flexion, 45° extension, and neutral), for three Jamar hand dynamometer spans. Thus, the model was a 2 (gender) x 2 (hand) x 3 (wrist position) x 3 (dynamometer span) x 20 (subjects) mixed effects model with blocking on subjects. Anthropometric dimensions of the subjects' hands were utilized to establish correlation between basic hand dimensions and grasp strength. A stepwise regression analysis established correlation between basic hand dimensions with grasp strength. An R² value of 0.82 was obtained for the regression equation developed for the largest span (6 cm) of the dynamometer with palm thickness, wrist circumference and forearm length as the independent variables and grasp strength as the dependent variable. For the middle span of 4.7 cm, however, it was seen that palm thickness, wrist circumference, and hand breadth were the only significant variables, with a coefficient of determination of 0.79. Therefore, these four dimensions were chosen for a correlation study with grasp strength. The correlation study revealed that wrist circumference has a reasonably good correlation between the non-dominant hand and the largest span of the handle in the neutral wrist position. Palm thickness and hand breadth yielded significance in two of the three handle spans. The ANOVA showed that all main effects, namely, wrist position, grip span, gender, and hand were significant at the 0.01 level.
    Limitations of Wrist Strength to Manual Exertion Capability in 2D Biomechanical Modeling BIBA 559-563
      Khaled W. Al-Eisawi; Carter J. Kerk; Jerome J. Congleton
    The objective of this study is to evaluate the assumption in biomechanical models that wrist strength does not limit manual exertion capability. An experiment was designed and run on right-handed males to test isometric elbow flexion strength at two included elbow angles: 90° and 135° and in two forearm positions: supinated and mid between supination and pronation. Isometric wrist flexion strength was also measured at the same elbow angles and at two wrist positions in the flexion/extension plane: neutral and 45° extended. Isometric wrist radial deviation strength was measured at the same two elbow angles and at two wrist positions in the radial/ulnar deviation plane: neutral and 30° ulnarly deviated. An equation was developed to calculate the theoretical minimum wrist strength limits for which wrist strength does not limit maximal moments about the elbow. These calculated limits were compared to the corresponding measured wrist strength moments. In general, wrist strength was found to be non-limiting, but in some specific circumstances, it can be limiting. Among the posture/exertion combinations tested, only wrist flexion strength in the extended wrist posture was found to be limiting. There was some evidence that strong-wrist people show less wrist strength limitations than weak-wrist people in some postures. It was also found that the neutral wrist posture is not associated with the highest wrist strength.

    INDUSTRIAL ERGONOMICS: Lifting and Carrying [Lecture]

    Postural Stability while Walking and Carrying Loads in Various Postures BIBA 564-567
      M. A. Holbein; M. S. Redfern
    Falls, over-exertion injuries and other potential consequences of balance losses continue to be serious ergonomic concerns. Stability issues are important in the prevention of these injuries, especially when the task is complicated by handling loads. However, stability analyses are not typical components of ergonomic job analyses. This study demonstrated that stability assessments can be effective in recommending load-carrying strategies. In particular, the effects of load positioning and magnitude on stability were investigated. Unladen walking was also tested for comparison. Several stability measures were defined based on the body-and-load's center of mass displacement in the frontal plane. Statistical differences among the load positions and magnitudes were found and are discussed. Results were consistent across measures. Additional work is needed to better define the limits of stability while carrying and to relate these, or other, stability measures to the likelihood of a balance loss.
    The Effects of a Stretcher-Carry Harness on Soldier Performance: Carrying from a Remote Area BIBA 568-572
      Valerie J. B. Rice; William J. Tharion; Marilyn A. Sharp
    This study investigated whether the use of a shoulder harness and team size would affect stretcher-carry performance and post-carry rifle marksmanship and fine-motor coordination following a carry from a remote site. Soldiers (12 male and 11 female) carried stretchers in two-and four-person teams, with and without a shoulder harness. Soldiers carried a stretcher at 4.8 km/hr for as long as possible, up to 30 min. Soldiers fired at targets and completed a fine-motor coordination task before and after each carry. Analysis of Variance and post-hoc Newman-Keuls Comparison of Means revealed significant rifle shooting impairments after stretcher-carrying (p < 0.001). Men carried the stretcher longer than women (p < 0.0001). Harness use and carrying in four-person teams prolonged carry time for both men and women, without decreasing shooting accuracy. Completion of a fine-motor coordination task was faster after using a harness vs a hand carry (p = 0.03) and working in four vs two-person teams (p < 0.02). Heart rate was lower during harness carries (p < 0.001). In conclusion, the ability to transport, medically treat, and protect patients is improved by harness use and working in four-person teams. It is suggested the policy of using four-person teams be enforced, and harness systems be included with the supply of stretchers for any situation that requires continuous stretcher-carrying of five minutes for four-person teams or two minutes for two-person teams.
    The Effects of a Stretcher-Carry Harness on Soldier Performance: A Mass Casualty Simulation BIBA 573-577
      Valerie J. B. Rice; William J. Tharion; Marilyn A. Sharp
    This study investigated whether the use of a shoulder harness and team size would affect stretcher-carry performance, post-carry rifle marksmanship, and post-carry fine-motor coordination during a mass casualty simulation. Twelve male and eleven female soldiers volunteered. Soldiers carried stretchers in two- and four-person teams, with and without a shoulder harness in a 15-minute bout of rapid, short stretcher-carries and lifts. Soldiers completed as many carries as possible within the allowed period. Soldiers completed a marksmanship and fine-motor coordination task before and after each 15-minute period. Analysis of Variance and post hoc Newman-Keuls Comparison of Means revealed significant rifle shooting impairments after stretcher-carrying (p < 0.02). Men completed more carries than women (p < 0.0001), and more four-person hand carries were completed than other team size x harness combinations (p < 0.01). Women's rifle marksmanship was better when carrying in four-person teams (p < 0.05), while men's rifle marksmanship performance was not significantly altered. The fine-motor coordination task was completed faster after using a harness (p = 0.03) and working in four-person teams (p < 0.02). The ability to transport, medically treat, and protect patients is improved by working in four-person teams. In conclusion, for a mass casualty scenario, tactical planning should allow for enough soldiers to be deployed to allow stretcher-carrying in four-person teams. A harness system should be available for exigencies requiring two-person teams.
    An Investigation of the Variability in Human Performance during Manual Material Handling Activities BIBA 578-582
      Gary A. Mirka; Ann Baker
    The goal of this study was to quantify the variability of the three-dimensional kinematic and kinetic parameters describing the motion of the torso during the performance of sagittally symmetric lifting tasks. Subjects performed eight repetitions of simple lifting tasks described by three levels of coupling (poor, fair and good) and seven levels of load (4.5, 9, 13.5, 18, 22.5, 27 and 31.5 kg). The three-dimensional, time dependent position, velocity and acceleration of the lumbar spine were monitored using the Lumbar Motion Monitor. These measures were then input into a dynamic biomechanical model which calculated torque about the L5/S1 joint in the sagittal plane. The results of the kinematic analysis showed significant variability in the magnitude of the peak velocity and acceleration in the sagittal plane and also showed significant motion in the transverse and coronal planes. The kinetic analysis showed an increase in the variability of the peak dynamic torque with greater levels of load but no coupling effect.

    INDUSTRIAL ERGONOMICS: Ergonomics in Space [Lecture]

    Evaluation of Crew Capabilities to Handle and Stabilize Heavy Masses in Microgravity BIBA 583-587
      Sudhakar L. Rajulu; Glenn K. Klute; Robert P. Wilmington
    One of the purposes of NASA's Shuttle missions is to deploy and retrieve satellites. Some of these missions require extravehicular activities (EVAs). During EVAs, crew members wear pressurized suits for protection from hazardous conditions and use a Remote Manipulator System (RMS) to transfer heavy objects from one location to another. Prior to the Hubble Space Telescope repair mission (STS-61), concerns were raised whether crew members would be able to hold onto the modules if the RMS started or stopped unexpectedly. An experiment was conducted to measure the handle forces during such a scenario and to determine whether these forces and moments were well within the capabilities of the crew. Four subjects participated in the study. Mockups were built to represent the characteristics of the actual unit and tests were conducted at the Precision Air Bearing Facility (PABF) which simulates a nearly friction-free environment. Force plates were attached to the mockups to monitor forces and moments during the test. Controlled translation and rotation tasks were also conducted to compare the results with those of sudden RMS run start/stop tasks. The results from this study showed that the forces and moments exerted by subjects during sudden stopping and starting conditions were well within the capabilities of the crew members. This study thus provided quantitative data for NASA to be assured of a safe and successful mission.
    Influence of a Pitch Adjustable Foot Restraint on Operator Induced Loads in Zero-Gravity BIBA 588-592
      Robert P. Wilmington; Jeffrey Poliner; Glenn K. Klute
    The zero-gravity environment creates a need for a proper human body restraint system to maintain a comfortable posture which lessens fatigue and maximizes productivity. In addition, restraint systems must be able to meet the loading demands of maintenance and assembly tasks performed on-orbit. The Shuttle's primary intravehicular astronaut restraint system is currently a foot loop design that attaches to flat surfaces. This restraint system allows for variation in mounting locations and ease of ingress and egress. However, this design limits performance because it does not allow for elevation, pitch, or foot loop length adjustment. Several prototype foot restraint systems are being evaluated for use aboard Space Station and the Space Shuttle. A study was initiated using NASA's reduced gravity aircraft quantifying differences observed in operator performance while adjusting the pitch angle of a prototype foot restraint. Pitch angle adjustments were made from 5° to 35°. While operators performed a torque wrench task using a hand hold and foot restraint, the maximum axial forces and moments induced on the restraint systems and torque wrench were recorded. Overall this study did not see any significant difference in the force operators could place on the torque wrench or forces imparted to the foot restraint system due to the pitch orientation of the foot restraint. Thus in a work environment in which hand holds are available, no significant influence of the pitch angle existed for operator performance or forces imparted to the restraint system.
    Strength Capabilities while Performing Torquing Tasks in Weightlessness BIBA 593-596
      Jeff Poliner; Robert P. Wilmington; Glenn K. Klute
    Knowledge of individuals' strength capabilities in weightlessness is of interest within many areas of NASA, including workplace design, tool development, and mission planning. This study was a generic examination of the loads produced by individuals performing maximal efforts with a torquing tool in zero-gravity. The study also examined the effects of orientation and direction of rotation of the tool on strength effectiveness. An experiment was conducted aboard NASA's reduced gravity aircraft which simulates brief periods of weightlessness. A test stand was developed and instrumented to measure the loads applied to fixed fittings. Eight male volunteers participated in this study in which they used a wrench to apply a maximum torque to fittings oriented along each of three orthogonal axes. It was seen that these subjects could produce approximately 400 to 750 N of force, depending on the orientation of the tool and the direction of effort. The most force could be produced when pushing the tool upwards. A force effectiveness ratio (FER) was defined as an indication of how much of the subject's total effort actually went into performing the desired task. Values of FER ranged from 0.55 to 0.90, with the greatest FER occurring with UP and DOWN efforts, and the lowest with AWAY and LEFT efforts. Designers can use these results to set specifications for craft structures; tools can be developed based on the known strength of the tool users; and tasks can be developed to not exceed the crewmembers' capabilities.
    Tactility as a Function of Grasp Force: Effects of Glove, Orientation, Load and Handle BIBA 597-601
      Ram R. Bishu; Lisa A. Bronkema; Dishayne Garcia; Glenn Klute; Sudhakar Rajulu
    The objectives of this research are to ensure that a reduction in tactile sensitivity was causing a reduction in gloved performance, and to measure this reduction in tactile sensitivity through grasp force at the hand/handle interface under a variety of performance conditions. The effects of glove type, load lifted, handle size, and handle orientation on the initial grasping force and stable grasping force were determined through a factorial experiment in which 10 subjects participated. The working hypothesis was that grasp force would be a function of all the above mentioned factors. The most consistent findings of this experiment were:
  • 1. Glove effect is marginal at submaximal exertions.
  • 2. The magnitude of force exertions in the advanced glove and bare handed
        conditions were similar.
  • 3. The magnitude of force exertion was the highest with meat packing gloves.
  • 4. The ratio of peak to stable grasp force increased with increasing loads.
  • 5. The glove effect for maximal exertions as seen in experiment 2 is consistent
        with published evidence. In conclusion, it is clear from these experiments that when people perform a grasping action, the maximal exertions are affected differently by gloves than sub-maximal or "just holding type of exertions."
  • INDUSTRIAL ERGONOMICS: Hand and Wrist Ergonomics II [Lecture]

    Dynamics of Power Hand Tools on Operator Hand and Arm Stability BIBA 602-606
      Seoungyeon Oh; Robert G. Radwin
    Threaded fastener tightening was studied to determine effects of tool dynamics (torque and build-up time) and workstation configuration (orientation, horizontal distance and height) on operator kinematics and ability to stabilize a right-angle power hand tool. Hand velocity, hand displacement, tool torque, and spindle angle were recorded during tool operation. Four subjects participated. Workstation factors and tool dynamics had significant effects on hand stability. The magnitude of hand velocity and displacement was significantly greater for (1) vertical work surfaces compared to horizontal work surfaces; (2) vertical work surfaces higher than 90 cm above the ground; (3) horizontal work surfaces 90 cm above the ground; (4) increasing torque levels, and (5) long torque build-up times. Subjective ratings of perceived exertion were greater for increasing torque levels, long build-up times, and increasing workstation heights. Perceived exertion was significantly related to hand velocity and displacement (p<0.05), however, the strength of the correlation was small (R² ranged between 0.01 and 0.10).
    The Surface Area and Volume of the Hand BIBA 607-610
      Bruce P. Mignano; Stephan Konz
    This article recounts our research on measuring the surface area of the human hand. The surface area is measured using a photometric technique. The change in illuminance in a specially constructed and calibrated light chamber is measured when a hand is placed in the chamber. The hand is clad in a black dyed latex glove. An equation was developed to predict the surface area of the hand, using easy to obtain hand dimensions as independent variables. Regression analysis was used to determine the significance of the independent variables. The analysis yielded an equation that can predict the surface area of the hand, using easily measured characteristics of the hand.
    Carpal Tunnel Pressure during Typing: Effects of Wrist Posture and Typing Speed BIBA 611-615
      Carolyn M. Sommerich
    With increasing frequency, reports appear in the popular press linking hand and wrist musculoskeletal disorders (MSDs) with keyboard work. Excessive ulnar deviation and self-perceived fast typing speed are two of the many risk factors identified through various epidemiological studies of upper extremity MSD symptoms among those working with keyboards. Yet no study has offered quantitative, biomechanical evidence to explain how these factors might contribute to MSD development. A study was designed to examine carpal tunnel pressure (CTP) during typing, and the effect of radial-ulnar wrist posture and typing speed on CTP. Female subjects typed on a commercially-available keyboard which was oriented in standard and in split configurations. In the split arrangement ulnar deviation was eased in all but one wrist. In the split arrangement, all subjects demonstrated a decrease in CTP concomitant with a decrease in ulnar wrist deviation. However, only one subject exhibited CTP which significantly exceeded pressure thresholds identified in the literature. CTP appeared to be subject-specific in nature. Typing speed was found to affect peak CTP in half of the subjects.
    The Effects of Human Interface Design on Wrist Biomechanics during Scanning BIBA 616-620
      Katherine R. Lehman; William S. Marras
    Two window, or "bi-optic" scanners have ergonomic potential to minimize cumulative trauma disorders (CTDs) among grocery checkers. However, not all checkers utilize both windows when scanning.
       Four, two window scanners were tested to see whether the number of windows used had an effect on wrist acceleration, one of the most predictive indicators of CTD risk. Out of 32 subjects, 14 used only one window while scanning. These subjects were seen to have significantly higher cumulative peak wrist accelerations than those subjects that used both windows. In addition, the productivity of the one window users was significantly lower than two window users.
       The results indicate that two window scanners can not only increase productivity, but can reduce the risk of CTDs. However, this will only occur if checkers appreciate and choose to use both windows in their scanning activity. The large number of subjects (14 out of 32) that only used one window when scanning indicates a serious human interface problem with these types of scanners.
       This paper identifies the need for better scanner designs that will indicate to the user the three-dimensional scan zone created by the two windows. The design should influence one to use both windows while scanning so that wrist motions will be reduced. Most importantly, this paper identifies the importance of the relationship between cognitive and biomechanical issues when approaching a human interface problem in a product's design.

    INDUSTRIAL ERGONOMICS: Psychophysical Methods [Lecture]

    Modelling the Additivity of Perceived Exertion in Symmetric, Mid-Sagittal Lifting BIBA 621-625
      Brian D. Lowe
    Psychophysical approaches to quantifying perceived effort have been used to evaluate the physical demand of many industrial work activities. An experiment was conducted to examine the relationship between ratings of whole-body perceived exertion and differentiated, regional ratings of exertion. The Borg, CR-10 scale was used by 16 subjects performing a simulated repetitive lifting task. Ratings of perceived exertion were obtained for the arms, legs, torso, and central (cardiorespiratory) effort sensations as well as a rating of overall, whole-body exertion. A multiple linear regression analysis was used to predict the whole-body rating of exertion from the differentiated ratings in lifting tasks using both a squat and stoop posture. In the stoop posture condition the coefficient of determination between whole-body perceived exertion and the model including arm, torso, and central ratings was R²=0.81. In the squat posture condition, the final regression model predicting whole-body exertion contained only the rating from the legs (R² = 0.62). Differentiated ratings explained the majority of the variance in whole-body perceived exertion for squat and stoop lifting tasks.
    Perceived Exertion Scales: Toward Development of Improved Verbal Anchors BIBA 626-630
      Sue Mason Angel; Robert J. Marley; Leann Stadtlander
    An experiment documented the choices of verbal anchors or word triggers by subjects observing five different videotaped work operations. Their surveyed numeric scalings and word selections were compiled to form a list of ten words which are recommended to describe amount or degree of work basing performed. This study acknowledges that there is inherent risk in applying words to work measurement scales, but the list may be helpful as a guide to choosing appropriate words to indicate work content or for job descriptions.
    The Effects of Different Forms of Space Restriction on Inspection Performance BIBA 631-635
      J. L. Reynolds; C. G. Drury; J. Sharit; F. Cerny
    Work in restrictive spaces is characteristic of many tasks, particularly in maintenance and inspection operations. The nature of the spatial restriction as well as its magnitude is likely to affect the worker's response to the space. This research measured the effects of three different spatial restrictions (vertical (V), sagittal (S) and combined (VS)) on an inspection task. The effects of the three restrictions on postural adaptation, physiological response, psychophysical reports and task performance were qualitatively different. Generally, the VS and V restrictions caused increases in operator stress and workload, with these effects being most severe under the VS restriction. Conversely, the S restriction caused no increases in operator stress and tended to improve performance. Thus, while restrictions are generally detrimental, certain mild restrictions may actually facilitate jobs.
    Psychophysical Cost Function of Joint Movement for Arm Reach Posture Prediction BIBA 636-640
      Eui S. Jung; Jaeho Choe; Sung H. Kim
    A man model can be used as an effective tool to design ergonomically sound products and workplaces, and subsequently evaluate them properly. For a man model to be truly useful, it must be integrated with a posture prediction model which should be capable of representing the human arm reach posture in the context of equipments and workspaces. Since the human movement possesses redundant degrees of freedom, accurate representation or prediction of human movement was known to be a difficult problem. To solve this redundancy problem, a psychophysical cost function was suggested in this study which defines a cost value for each joint movement angle. The psychophysical cost function developed integrates the psychophysical discomfort of joints and the joint range availability concept which has been used for redundant arm manipulation in robotics to predict the arm reach posture. To properly predict an arm reach posture, an arm reach posture prediction model was then developed in which a posture configuration that provides the minimum total cost is chosen. The predictivity of the psychophysical cost function was compared with that of the biomechanical cost function which is based on the minimization of joint torque. Here, the human body is regarded as a two-dimensional multi-link system which consists of four links; trunk, upper arm, lower arm and hand. Real reach postures were photographed from the subjects and were compared to the postures predicted by the model. Results showed that the postures predicted by the psychophysical cost function closely simulated human reach postures and the predictivity was more accurate than that by the biomechanical cost function.


    Lessons Learned from a Retail Food Industry Ergonomics Task Force BIBA 641-643
      Thomas J. Sluchak; Charles I. Miller; Peter R. Labbe; Mark S. Hoffman
    Three individuals on the panel have participated in the formation and functioning of the Food Marketing Institute Ergonomics Task Force; the retailer on the panel has benefited from the recommendations of the task force. The panelists will discuss lessons learned from the task force activity both for the retail food industry and for individual stores.

    INDUSTRIAL ERGONOMICS: Lifting [Lecture]

    A Study of the Interaction between Load and Coupling during Lifting BIBA 644-648
      Gary Mirka; Ann Baker; Angela Harrison; Dan Kelaher; Joseph Davis
    The National Institute for Occupational Safety and Health (NIOSH) has increased the applicability of its lifting equation to a wider range of jobs by relaxing some of the simplifying assumptions of the original equation. Specifically, NIOSH has added an asymmetry factor and a coupling factor in the revised lifting equation. Two of the remaining simplifications, however, are that (1) interactions between terms are not considered and (2) the biomechanical analysis still utilizes a static modelling approach in its calculations. The purpose of the present research was to investigate the interaction between coupling and load magnitude under dynamic lifting conditions. Subjects lifted a box under various combinations of coupling and load. The dependent variables in this study were the peak external moment about the lumbosacral joint (as calculated by a dynamic biomechanical model) and the peak vertical ground reaction forces. The results show that at low levels of load there was little difference in peak torque across the different coupling conditions. However, when loads greater than 13.5 kg were combined with poor coupling, there was a fundamental change in the dynamics of the lifting motion. The results of this study indicate that the role of coupling under dynamic lifting conditions has both a perceptual and biomechanical effect which should be considered when designing manual materials handling tasks.
    The Effects of Task Conditions on Trunk Muscular Fatigue during Dynamic Lifting BIBA 649-653
      Sang H. Kim; Min K. Chung; Wook G. Lee
    To investigate the effects of MMH task conditions on the activity and fatigue of the trunk musculature, EMG signals from eight major trunk muscles were analyzed during 120 minutes of repetitive dynamic lifting tasks. Two independent task variables were the work strategy of weight and lifting frequency combination and the body posture. The dependent variables were the amplitude of EMG signals and the amount of median power frequency (MPF) decrease over time for the eight trunk muscles. The results of the study indicated that the recruitment and the level of force exertions of the trunk muscles during manual lifting tasks are a function of the direction and the weight of the external load. The different activities of the muscles due to given task conditions also influence the fatiguing process of the individual muscle. The muscles in the dorsal part of trunk were activated during the symmetric task conditions, while the muscles on the contralateral side to the workload were more strongly activated during the asymmetric task conditions. The decreasing trends of MPF were found in some activated muscles, and they were more pronounced for the asymmetric posture than for the symmetric posture. It was also seen that the muscles became fatigued faster for light load-high frequency conditions than for heavy load-low frequency conditions.
    Relationships between the NIOSH (1991) Lifting Index, Compressive and Shear Forces on the Lumbosacral Joint, and Low Back Injury Incidence Rate Based on Industrial Field Study BIBA 654-657
      Waldemar Karwowski; Marenda Caldwell; Paul Gaddie
    The main objective of this study was to investigate relationships between the values of NIOSH (1991) Lifting Index calculated for as set of industrial manual handling tasks, the corresponding (estimated) compressive and shear forces on the lumbosacral joint (L5/S1), and the back injury incidence rates based on analysis of the epidemiological field data. A strong positive correlation was observed between the estimated compressive forces on L5/S1 and the lifting index (LI) values, and between the incidence rates (IR) of low back injury and the LI index. Two sets of regression models describing the relationships between the lifting index (LI) and the compressive forces on the L5/S1 were developed. It was shown that the LI=1.0 corresponds to about 1.8 kN and 2.4 N of compression on the L5/S1, for the destination and origin of the lift, respectively. For the lumbar compressive strength values (with safety factor of one standard deviation) of 4.1 kN for males (40 years of age), proposed by Jager and Luttman (1992), the corresponding values of the lifting index are as follows: LI=4.1 (for the lift destination) and 6.4 (for the lift origin). Implications of results for prevention of back injury due to manual lifting were discussed.
    Age Effects in Biomechanical Modeling of Static Lifting Strengths BIBA 658-661
      Don B. Chaffin; Charles B. Woolley; Trina Buhr; Lois Verbrugge
    There is growing awareness that age results in reduced strengths in the population, and that significant decreases start in the 5th decade. The magnitude of the decrease in strength depends on the specific muscle function being tested. Because of differential effects it is not clear how various decreases could alter whole-body strength performance. This paper describes how specific strength decreases measured in an older population of men and women could affect their whole-body exertion capabilities in selected scenarios. A computerized strength prediction program is used to both predict the whole-body strength changes with age, and to study how older populations can alter their postures to achieve maximum exertion capability. The results indicate that different muscle group strengths decline by 5% to 70% with age, depending on which muscle group is tested. These changes have profound effects on whole-body exertion capabilities, which also are shown to depend on specific postures used to perform the exertions.


    Ergonomics Problem Solving BIBA 662-663
      David C. Alexander; Thomas J. Albin; W. Monroe Keyserling; Sheryl S. Ulin; Chris J. Henderson
    The analysis and resolution of many ergonomics problems has been widely reported in the literature and in presentations at technical and professional meetings. What has not been explored as thoroughly is the process by which those problems are approached and the process which is followed in resolving the problems. From the articles and presentations, there does not appear to be a uniformly consistent approach. These panelists will discuss their process of solving ergonomics problems, including the techniques and resources utilized.

    INDUSTRIAL ERGONOMICS: Ergonomic Applications I [Lecture]

    High Technology and Manufacturing: Work Physiology Improvements via the Ergonomic Simulation Analysis System BIBA 664-667
      Leighton L. Smith
    This article describes an ergonomic analysis tool called the Ergonomic Simulation Analysis System (ESAS). This system is used in conjunction with computer graphic simulation software. The ESAS integrates work physiology ergonomic models and indexes with manufacturing workplace simulation. It enables engineers and analysts to extract from the simulation sequences robust and meaningful ergonomic analyses in lifting and in repetitive motion activities. The system is simple to operate, allows analysts to execute its functions in a seamless manner when using other software, provides robust results with very little setup time investment, and provides effective and readily assimilated visual products of candidate workplace designs and work methods.
    Adjustable Sit-Stand Workstations in the Office BIBA 668-672
      Heather L. Nerhood; Steven W. Thompson
    This study describes the approach taken and the results measured thus far from the introduction of sit-stand workstations in an office environment. Adjustable workstations have been developed and introduced in an office within United Parcel Service (UPS). A sit-stand workstation consists of the following components: modular panel walls, an adjustable front work surface, an adjustable rear work surface, and an adjustable chair. An employee can sit or stand while working and perform the adjustments to the workstation with fingertip ease and control.
       The job requirements of all of the employees using the new workstations are sedentary in which there is constant use of the computer to perform a variety of tasks. A training program was also introduced to review basic principles of human factors and ergonomics and to provide instruction in how to properly use the new workstations, chairs, and other accessories.
       Prior to the installation of the workstations, various benchmark data were collected including: production levels, absenteeism, and injuries and illnesses. A survey of body part discomfort identified areas that were of concern. Following the installation of the workstations, the same data have been and will continue to be collected to measure the effectiveness of the ergonomic interventions. Body part discomfort decreased by an average of 62 percent. Production in two departments that were monitored demonstrated improvement, however at this time the study cycle is too short to hypothesize long term results. The occurrence of injuries and illnesses decreased by more than half. Absenteeism did not show significant changes. These data will continue to be tracked to measure the results of the interventions.
    Customer Service at the Checkout: Relating Productivity, Ergonomics, and Front-End Management Issues BIBA 673-677
      Mark S. Hoffman
    There has been a growing body of research over the past several years exploring repetitive behaviors of cashiers in supermarket checkouts. These studies were designed to increase the knowledge about biomechanical and physiologic stressors on the cashier during their most repetitive tasks, scanning products, rather than understand the impact of these tasks on customer service. The research described in this paper summarizes results from over thirty recent studies to determine the corroboration of these findings with the biomechanical research. The results from these productivity analyses showed that when effects of staffing, mixes of transaction sizes and types of tendering are normalized, the Front Facing checkstand was the most productive during the most repetitive tasks, scanning and keying product information, and from the total transaction time. These findings are similar and support those previously reported in the biomechanical research on cashiers using scanners.
    A Method to Measure Discomfort of Static, Submaximal Force Exertion BIBA 678-682
      Brechtje J. Daams
    The degree of discomfort during force exertion is little investigated in literature. In daily life, however, comfort is an important aspect when using or operating products. It would therefore be useful for designers to know about the subjective experience of (dis)comfort during the exertion of submaximal forces by users of products. No standard measurement methods were found in literature. Two experiments have been carried out, using different methods.
       The first experiment was combined with the measurement of endurance time at different force levels and in four different postures. Subjects were asked every half minute to rate the discomfort they experienced on a five-point scale. Alas, the results generated by this method were found to be not sufficiently reproducible.
       The second experiment was set up in such a manner as to prevent subjects thinking explicitly about their feelings. This time, only one posture was investigated (pushing with the arm) and a spontaneous change of posture was taken as an indication of discomfort. The time to the first change increased consistently with lower force levels and these results proved to be sufficiently reproducible. Therefore this measurement method is recommended to get an idea about the level of discomfort experienced by subjects. A formula is given to indicate the relation found between the force level and the median of the time to the first change of hand.

    INDUSTRIAL ERGONOMICS: Ergonomic Applications II [Lecture]

    Physical Demands of Work Are the Common Reference for an Integrated Ergonomics Program BIBA 683-687
      Robert L. Getty
    The integration of all of an organization's processes must occur for the achievement of a successful ergonomics program. OSHA guidelines for ergonomics suggest the essential elements are management commitment, employee involvement, medical management, worksite analysis and training. This paper will briefly show how the physical demands analyses (PDAs) at Lockheed Fort Worth Company (LFWC) were developed and utilized by various entities within the company. The focus on physical demands becomes the cornerstone for more than the post injury focus of OSHA ergonomic guidelines. Emphasis on physical demands leads to the prevention of future injuries, improvements in productivity and quality, as well as the design of new processes within the company.
    Contact Area Effects on Discomfort BIBA 688-690
      Ravindra S. Goonetilleke; Timothy J. Eng
    Most "ergonomic" products attempt to adopt a uniform force distribution strategy to improve comfort. The rationale being that force distribution over a large area reduces pressure and thereby enhances user comfort. However, sensory literature alludes to the concept of spatial summation, i.e. greater sensation by stimulating a larger surface area. Hence spatial summation would tend to suggest a greater discomfort when forces are applied over large surface areas. This study reports the effect of surface area on maximum discomfort causing pressure or maximum pressure tolerance (MPT). Two circular probes of different cross sectional area were used to stimulate the skin surface. The mean MPT with a probe of 5mm diameter was 3.3 times higher than the MPT with a probe of 13mm diameter. These findings suggest the following:
  • Perceived discomfort and contact area seem to have a "U-relationship" above a
       critical force value. Traditional thinking of distributing forces is
       successful only in the first half of the U-curve or with forces below the
       critical value. The section with the monotonically increasing relationship
       between disconcert and contact area (i.e., second half of U) may not be seen
       at very low forces or forces below the critical value.
  • "High" pressures in concentrated areas may cause less discomfort than
       "moderate" pressures over a larger area.
  • The critical or threshold pressure to induce discomfort is force and contact
       area dependent.
  • Ergonomics in Product Design Solves Manufacturing Problems: Considerating the Users' Needs at Every Stage of the Product's Life BIBA 691-695
      Christopher A. Dockery; Thomas Neuman
    This paper demonstrates a systematic process for effectively considering in the product design process the ergonomics requirements of all who will interact with a product during its entire life cycle. This process goes beyond applications of ergonomics commonly found in industry. Development of the process is discussed. Several case studies from large corporations illustrate the application of the process including: deficiencies in conventional design processes relative to order of events, time requirements, effectiveness of the final design, and project scope. The product design process is discussed relative to when and how ergonomics should be included. Relationships are explored between ergonomics, the process, and the following concepts: design for manufacturability; design for serviceability; total quality management; customer driven products; flexible manufacturing.
    The Economics of Ergonomics BIBA 696-704
      David C. Alexander
    The economics of ergonomics is important from a managerial and technical standpoint. This paper provides an overview of the economics of ergonomics, both from a conceptual standpoint and from a practical standpoint. The economics at the project level as well as economics at the program level are discussed. There are a number of possible techniques to use and the advantages and disadvantages of them are presented. Some techniques work better under some circumstances than under other circumstances. Finally, a short list of ways to control costs within an ergonomics program is provided.