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

Proceedings of the Human Factors Society 33rd Annual Meeting 1989-10-16

Fullname:Proceedings of the Human Factors Society 33rd Annual Meeting
Location:Denver, Colorado
Dates:1989-Oct-16 to 1989-Oct-20
Standard No:ISSN 0163-5182; hcibib: HFS89-1
Links:Online Proceedings
  1. HFS 1989-10-16 Volume 1
    1. Presidential Address
    2. Aerospace Systems: Spatial Awareness and Map Displays
    3. Aerospace Systems: Situational Awareness and 3-D Displays
    4. Aerospace Systems: Air Traffic Control
    5. Aerospace Systems: Aviation Controls and Displays
    6. Aerospace Systems: Obtaining New Perspectives with Head-Coupled Simulators
    7. Aerospace Systems: Predictive Performance Models and Multiple Task Performance
    8. Aerospace Systems: Simulation and Decision Aiding
    9. Aerospace Systems: Space-Related Activities
    10. Aging: Older People and New Cars
    11. Aging: Performance and Cognition in Older Persons
    12. Aging: Environments, Products, and Technologies for the Aging Population
    13. Aging: Panel
    14. Communication: Communications Case Studies
    15. Communication: Methods for Interface Design
    16. Communication: Language Processing and Voice Interfaces
    17. Computer Systems: Panel
    18. Computer Systems: Tools for User Interface Design
    19. Computer Systems: Approaches to User Interface Design
    20. Computer Systems: Panel
    21. Computer Systems: Modeling
    22. Computer Systems: Speech and Writing
    23. Computer Systems: Touch and Gesture
    24. Computer Systems: Panel
    25. Computer Systems: Input Device Comparisons
    26. Computer Systems: Applications of Computer Systems
    27. Computer Systems: Formulation of Expert System Knowledge
    28. Computer Systems: Displays and Graphics
    29. Computer Systems: On-Line Information/Expert Systems
    30. Computer Systems: Computer Systems Potpourri
    31. Consumer Products: Warnings!
    32. Consumer Products: Computer Hardware Design
    33. Consumer Products: Panel
    34. Consumer Products: Potpourri I
    35. Consumer Products: Potpourri II
    36. Educators' Professional: Human Factors Education: Issues and Answers
    37. Educators' Professional: Demonstration
    38. Educators' Professional: Educating from A Group Perspective: What, Why, and How
    39. Environmental Design: Occupied Indoor Space
    40. Environmental Design: Space and Transportation
    41. Environmental Design: Panel
    42. Forensics Professional: Forensics Forum: Research for Litigation
    43. General Sessions: Panel
    44. General Sessions: The Work of the NAS/NRC Committee on Human Factors
    45. General Sessions: Coping with Automation: Testing the Limits of Human Performance
    46. General Sessions: Panel
    47. General Sessions: Innovative Methods and Techniques in Applied Human Factors
    48. General Sessions: Automobiles and Highways
    49. General Sessions: Panel
    50. Industrial Ergonomics: Strength Assessment
    51. Industrial Ergonomics: Manual Materials Handling
    52. Industrial Ergonomics: Occupational Biomechanics
    53. Industrial Ergonomics: Industrial Ergonomics Case Studies
    54. Industrial Ergonomics: Hand/Wrist Characteristics
    55. Industrial Ergonomics: Prevention of Cumulative Trauma Disorders
    56. Industrial Ergonomics: Determining Human Capacities in Industrial Ergonomics
    57. Industrial Ergonomics: Panel
    58. International Technology Transfer: Dimensions for International Technology Transfer

HFS 1989-10-16 Volume 1

Presidential Address

Reflections on Human Error: Matters of Life and Death BIBA 1-7
  Earl L. Wiener
The last two decades have witnessed a rapid growth in the introduction of automatic devices into aircraft cockpits, and elsewhere in human-machine systems. This was motivated in part by the assumption that when human functioning is replaced by machine functioning, human error is eliminated. Experience to date shows that this is far from true, and that automation does not replace humans, but changes their role in the system, as well as the types and severity of the errors they make. This altered role may lead to fewer, but more critical errors. Intervention strategies to prevent these errors, or ameliorate their consequences include basic human factors engineering of the interface, enhanced warning and alerting systems, and more intelligent interfaces that understand the strategic intent of the crew and can detect and trap inconsistent or erroneous input before it affects the system.

Aerospace Systems: Spatial Awareness and Map Displays

Spatial Cognition and Navigation BIBA 8-12
  Anthony J. Aretz
This paper describes an experiment that provides data for the development of a cognitive model of pilot flight navigation. The experiment characterizes navigational awareness as the mental alignment of two frames of reference: 1) the ego centered reference frame that is established by the forward view out of the cockpit, and 2) the world centered reference frame that is established by the aircraft's location on a map. The data support a model involving at least two components: 1) the perceptual encoding of the navigational landmarks, and 2) the mental rotation of the map's world reference frame into alignment with the ego centered reference frame. The quantitative relationships of these two factors are provided as possible inputs for a computational model of spatial cognition during flight navigation.
Cognitive Perspectives on Map Displays for Helicopter Flight BIBA 13-17
  Kelly Harwood
Currently accessible technologies are providing entirely new display concepts for enhancing helicopter navigation. Yet the effectiveness of such displays depends on the extent to which they are configured according to principles from research on human performance. Computer generated map displays in the present study were configured according to previous research on maps, navigational problem solving, and spatial cognition in large scale environments. Interest centered on the representation of different spatial relationships that would best support helicopter navigational problem solving. One map display emphasized the global relationships between objects in the environment. The other map showed the pilot's relationship to objects as he travelled through the environment. Twenty skilled pilots used the maps to complete several navigational tasks that occurred within a realistic simulation program tailored for helicopter navigation. Findings indicate that the type of task and mode of flight (low level or Nap of the Earth (NOE)) are important determinants of map display effectiveness.
Instrument Scanning and Subjective Workload with the Peripheral Vision Horizon Display BIBA 18-22
  Donald Hameluck; Paul Stager
The Peripheral Vision Horizon Display (PVHD) is an expanded artificial horizon line that is intended to provide the pilot with orientation information through peripheral vision. The potential advantage is a reduction in the requirement to constantly refer to the attitude indicator (AI) in order to maintain awareness of orientation during instrument meteorological conditions (IMC). Four helicopter pilots flew two types of instrument approaches to determine whether the degree to which pilots rely on the AI would be altered when the PVHD was in operation. Only two pilots showed a reduction in the visual workload associated with the need to scan the AI. The general trend in the data indicated an increase in subjective workload with the PVHD. It was argued that motion of the PVHD distracted the pilots from their routine instrument scan, although this result might not generalize to pilots more experienced with the display. It was concluded that the PVHD might be of significant benefit in situations where the pilot must look outside the cockpit and stable orientation cues are not visible.

Aerospace Systems: Situational Awareness and 3-D Displays

3-D in Pictorial Formats for Aircraft Cockpits BIBA 23-27
  Thomas C. Way
Sixteen military pilots flew simulated air-to-air and air-to-ground missions in a simulated fighter-attack cockpit. Three of the five color CRTs in the cockpit were capable of displaying retinal disparity and the major independent variable was presence or absence of disparity. Performance, workload, and opinion data were collected. A second objective of the study was to continue development of the display formats, which had evolved through earlier projects. The disparity results and the recommended format revisions are presented.
Situation Awareness: Icons vs. Alphanumerics BIBA 28-32
  Bruce A. Steiner; Monica J. Camacho
This study examined the effect of varying the amount of information that is presented in either an alphanumeric or iconic display and its effect on how efficiently a pilot can utilize the data. The results from 12 subjects, under self-paced presentation length conditions, indicated that for a small quantity of data (2 or 4 bits) there is no difference in response times between iconic and alphanumeric displays. As the quantity of data presented increases (8, 16, or 32 bits), subjects perform better using iconic displays.
The Effect of Windscreen Bows and HUD Pitch Ladder on Pilot Performance during Simulated Flight BIBA 33-37
  John E. Deaton; Michael Barnes; Nancy Lindsey; Janettarose Greene; Jonathan Kern
During the upgrade of the F-14 to the F-14D, pilots have expressed their concerns regarding the obscuration of the forward field-of-view due to the new Head-Up Display (HUD) supports in conjunction with preexisting windscreen bows. An additional issue involved the proposed use of the HUD as the primary flight reference instrument. The HUD pitch ladder has been criticized for not providing enough information to enhance recovery from unusual attitudes. The purpose of the present study was twofold: (1) to measure the levels of "target" detection with and without windscreen bows, and (2) to measure unusual attitude recovery performance using two different HUD pitch ladder formats. During simulated flight, 12 subjects were required to make visual detections of enemy aircraft with and without the bows. Subjects were also required to recover from various pitch/roll combinations. Removal of the bows improved target detection. Results of the obscuration study showed that in the first 5 seconds into the flight 80% of the targets were detected with bows off, while only 60% were detected with bows on. Evaluation of the two HUD pitch ladder formats revealed that, at severe negative pitch attitudes, there was a marked performance benefit with the Enhanced HUD vice the Standard HUD. Possible improvements in current HUD pitch ladder formats were suggested which would convey more cues to accurately and rapidly determine aircraft attitude.
Considerations of Noise for the Use of Compressed Speech in a Cockpit Environment BIBA 38-42
  Lorri J. Crittenden; Newton C. Ellis; Rodger J. Koppa
This research investigated the feasibility of using time compressed speech in a cockpit environment by examining the effect of cockpit noise on the intelligibility and comprehensibility of compressed speech. Research participants listened to cockpit-oriented verbal messages and were required to write them down afterwards. Results revealed a significant difference in compression levels between the environment without the ambient cockpit noise and the noise environment. The primary finding of this study was an interaction between noise and compression level. Implications of this research are made for the design of advanced crew systems.

Aerospace Systems: Air Traffic Control

Underlying Factors in Air Traffic Control Incidents BIBA 43-46
  Paul Stager; Donald Hameluck; Rebecca Jubis
As part of a continuing investigation of the conditions associated with operating irregularities in air traffic control (ATC), reports prepared during the investigation of 301 operating irregularities were analyzed in order to identify the factors most likely to precipitate air traffic control incidents. Operating irregularities were found to occur more frequently under conditions of moderate or low workload and normal complexity. A second objective of the work has been to develop a database system from which statistical data on operating irregularities and the various identified factors can be extracted. However, in order to enhance the integrity of the descriptive information in the database, the category structure that has been used to record the occurrence of ATC incidents is being revised to reflect the contemporary approaches to human error. A brief description of the proposed structure is included in the present paper.
Modeling Air Traffic Controller Performance in Highly Automated Environments BIBA 47-51
  Elizabeth D. Murphy; Ray A. Reaux; Lisa J. Stewart; William D. Coleman; Kelly Harwood
As increasing levels of automation are planned for the United States' air traffic control system, there is a need to assess planned system design changes for their potential effects on human performance. The model of controller performance developed by this work permits the comparison of prior and planned system transition states on several performance dimensions: perceptual, analytic, response, and resource management. Systematic predictions of performance provide a basis for identifying potential trouble spots in a planned system. The model can be employed to determine whether system design changes will improve controller performance without placing unreasonable demands on the controller's resources. It can be tailored to represent human performance variables and sources of resource demand in any complex automated system.
Building a Modeling and Simulation Analysis Tool to Predict Air Traffic Controller Workload and Performance BIBA 52-56
  Ray A. Reaux; Elizabeth D. Murphy; Lisa J. Stewart; Janet L. Gresh; Karin Bruce
To meet expected increases in domestic air traffic, the Federal Aviation Administration (FAA) will increase the level of automation in the domestic air traffic control (ATC) system. There is a need to assess the effects of the increased automation on controller workload and performance. Software-based engineering tools are needed to automate the analysis, allowing designers to identify potential problems early in the system design lifecycle. This paper describes one such tool, the Predictive Air Traffic Controller Analysis Model (PATCAM), a modeling and simulation analysis tool that uses a system operations concept and task attributes database, a controller activities model, a sector environment model and simulation engine, and a workload or performance model to predict the impact of system design changes on controller workload or performance.
Data Link Communications in the National Airspace System BIBA 57-60
  Alfred T. Lee
In the near future, conventional radio communications, currently the primary medium for the transfer of information between aircraft and ground stations, will be replaced by digital data link. This paper briefly describes this technology and summarizes what are believed to be the principal human factor issues associated with data link implementation in the airspace system. Integration of data link communications with existing systems on the flight deck and in the Air Traffic Control system is discussed with regard for both near term implementation and longer term operational issues.

Aerospace Systems: Aviation Controls and Displays

Investigation of Display Issues Relevant to the Presentation of Aircraft Fault Information BIBA 61-65
  Donald M. Allen
This research performed as a part of NASA Langley's Faultfinder project investigated display implementation issues related to the introduction of real-time fault diagnostic systems into next generation commercial aircraft. Three major issues were investigated: visual display styles for presenting fault related information to the crew, the form the output from the expert system should take and methods for filtering fault related information for presentation to the crew. Twenty-four flight familiar male volunteers participated as subjects. Five subjects were NASA test pilots, six were commercial airline pilots, seven were Air Force Lear Jet pilots, and six were NASA personnel familiar with flight (non-pilots). Subjects were presented with aircraft subsystem information on a CRT screen. They were required to identify the subsystems presented in a display and to remember the state (normal or abnormal) of subsystem parameter information contained in the display. The results of the study indicated that in the simpler experimental test cases (i.e. those involving single subsystem failures and composite hypothesis displays) subjects performance did not differ across the different display formats. However for the more complex cases (i.e. those involving multiple subsystem faults and multiple hypotheses displays) subjects performance was superior in the text- and picture-based display formats compared to the symbol-based format. In addition, the findings suggest that a layered approached to information display is appropriate.
Advanced Warning/Caution/Advisory Displays for Fighter Aircraft BIBA 66-70
  John M. Reising; David C. Hartsock
The primary purpose of this study was to determine the effectiveness of using color cathode ray tube (CRT) checklists and programmable multifunction switches to display warning/caution/advisory (W/C/A) information. This study compared three different display formats on speed and accuracy of recognition and execution of emergency procedures. The following three different W/C/A formats were tested: 1) Abbreviated title of the emergency written on a CRT [e.g., ELEC SYS/MAIN GEN], with the pilot using his knee pad checklist to complete the required steps, 2) Complete title with the checklist shown on a CRT [e.g., MAIN GENERATOR FAILURE/ELEC RESET SWITCH-DEPRESS], and 3) Complete title with the checklist plus the pictorial switch layout [i.e., CRT showing location of switch to be pressed]. Results showed that there is a definite advantage in using a CRT W/C/A checklist. Event time for the Abbreviated Title/Manual Checklist was significantly longer than either the Complete Title/CRT Checklist or the Complete Title/CRT Checklist with pictorials. However, there was no difference in event time between the latter two.
Touch Panel Sampling Strategies and Keypad Performance Comparisons BIBA 71-75
  Dennis B. Beringer
A study was conducted to improve accuracy of touch input devices to be used in helicopter environments through serial sampling and minima selection algorithms. Neither first nor last contact point was congruent with point of minimum error and sampling techniques were derived to reduce error without using "touch-mouse" strategies, being most effective for the infrared panel. Wearing flight gloves and using the nonpreferred hand had no practical detrimental effects on performance for a high-resolution touch input task. In a second study several types of mechanical keypads were compared with the two types of touch-input devices. Results obtained with this menu-selection task suggested no practical degradation in performance when substituting the touch input devices for bezel-mounted hardware keys. This was true of both error rate (in a qualified sense) and response time. It was concluded that the touch-input devices could provide flexibility for high-resolution input using maps and other spatial forms of data while allowing effective use of previously developed menus and menu-selection routines without the need for auxiliary bezel-mounted mechanical keys.
Visual Scanning With or Without Spatial Uncertainty and Time-Sharing Performance BIBA 76-80
  Yili Liu; Christopher D. Wickens
We report here an experiment that examines the pattern of task interference between visual scanning as a sequential and selective attention process and other concurrent spatial or verbal processing tasks. A distinction is proposed between visual scanning with or without spatial uncertainty regarding the possible differential effects of these two types of scanning on interference with other concurrent processes. The experiment required the subject to perform a simulated primary tracking task, which was time-shared with a secondary spatial or verbal decision task. The relevant information that was needed to perform the decision tasks were displayed with or without spatial uncertainty. The experiment employed a 2 X 2 X 2 design with types of scanning (with or without spatial uncertainty), expected scanning distance (low/high) and codes of concurrent processing (spatial/verbal) as the three experimental factors. The results provide strong evidence that visual scanning as a spatial exploratory activity produces greater task interference with concurrent spatial tasks than with concurrent verbal tasks. Furthermore, spatial uncertainty in visual scanning is identified to be the crucial factor in producing this differential effect. Theoretical and practical implications of these results are also discussed.

Aerospace Systems: Obtaining New Perspectives with Head-Coupled Simulators

Obtaining New Perspectives with Head-Coupled Simulators BIBA 81
  Maxwell J. Wells
Head-coupled simulators consist of a head-mounted display, an image generator and a head position sensor. By measuring where the head is pointing, and displaying the appropriate visual information on the display, the wearer can be presented with a simulated visual environment. The integration of the devices with display to the other sensory modalities means that the user could also be presented with simulated auditory, tactile, and kinesthetic information. The technologies for use in head-coupled simulators are evolving to make them cheaper, lighter and more readily available.
   The objective of this symposium is to act as a forum for the presentation and discussion of some of the many current applications of head-coupled simulators. The range of empirical studies which will be covered will demonstrate the flexibility and applicability of these devices. It is envisioned that the reduction in the need for the expensive and cumbersome equipment associated with traditional simulators will make head-coupled simulators of interest to the human factors community.
Head-Mounted Displays and the Measurement of Performance in a Virtual World BIBA 82-85
  C. Thomas Bennett
This paper is part of symposium entitled "Obtaining New Perspectives with Head Coupled Simulators." The paper's purpose is to present and discuss the problems associated with assessing visual performance during translation and rotation in a virtual world. Two studies are summarized which highlight the difficulties in defining and measuring the optical and visual variables that pilots use during the control of a craft in simulated flight.
Helmet Mounted Display Systems for Helicopter Simulation BIBA 86-90
  Loran A. Haworth; Nancy Bucher; David Runnings
Simulation scientists continually pursue improved flight simulation technology with the goal of closely replicating the "real world" physical environment. The presentation/display of visual information for flight simulation is one such area enjoying recent technical improvements that are fundamental for conducting simulated operations close to the terrain. Detailed and appropriate visual information is especially critical for Nap-Of-the-Earth (NOE) helicopter flight simulation where the pilot maintains an "eyes-out" orientation to avoid obstructions and terrain. This paper elaborates on the visually-coupled Wide Field Of View Helmet Mounted Display (WFOVHMD) system technology as a viable visual display system for helicopter simulation. In addition the paper discusses research conducted on the NASA-Ames Vertical Motion Simulator that examined one critical research issue for helmet mounted displays.
The Effect of Increasing Task Complexity on the Field-of-View Requirements for a Visually Coupled System BIBA 91-95
  Maxwell J. Wells; Michael Venturino
Ten subjects performed a task on a head-coupled simulator using various sized fields-of-view (FOVs). The task required them to visually acquire, remember the location of, monitor and shoot 3 or 6 objects. In addition they were required to perform a secondary tracking task. Performance at monitoring and shooting the objects decreased with decreasing FOV size and increasing number of objects. Secondary task performance also decreased with decreasing FOV. The ability to recall the location of objects was unaffected by changes in FOV size. However, tracking performance was degraded while subjects used smaller FOVS to find and learn the location of objects. The results indicate that although visual search performance can be maintained with small FOVs, it is done in a manner which may compromise performance at other tasks.

Aerospace Systems: Predictive Performance Models and Multiple Task Performance

Predictive Performance Models and Multiple Task Performance BIBA 96-100
  Christopher D. Wickens; Inge Larish; Aaron Contorer
This symposium presents five models that predict how performance of multiple tasks will interact in complex task scenarios. The models are discussed, in part, in terms of the assumptions they make about human operator divided attention. The different assumptions about attention are empirically validated in a multitask helicopter flight simulation reported in the present paper. It is concluded from this simulation that the most important assumption relates to the coding of demand level of different component tasks. The potential gains to be made multiple resource assumptions remain uncertain.
Global Task Management as Implemented in HOS-IV BIBA 101-104
  Helene P. Iavecchia; Regina M. Harris
The Human Operator Simulator (HOS-IV) is a general purpose simulation tool. It can be used to simulate the dynamic interactions of the environment, the hardware/software system, as well as the operator. HOS-IV provides time and accuracy data for a core set of cognitive, perceptual, and psychomotor processes. The focus of this paper is the HOS-IV mechanism that is used to simulate global task management. A sample application that demonstrates HOS-IV task management is also presented.
On Developing Theory-Based Functions to Moderate Human Performance Models in the Context of Systems Analysis BIBA 105-109
  Kevin Boettcher; Robert North; Victor Riley
Preliminary work is described toward the development of moderator functions for systems analysis that reflect human behavioral limitations and tendencies. In particular, a model of human-machine interaction dynamics in complex systems is introduced to give a moderating influence on overall operator/decision aid performance. A key input to this model is the operator's current workload. To further ground the moderator function in human behavioral considerations, a multiple resource theory-based workload assessment technique is used to provide this input.
Task Network Modeling as a Basis for Analyzing Operator Workload BIBA 110-114
  K. Ronald, Jr. Laughery
This paper discusses a technique for predicting human workload which is based around task network modeling. Task network modeling allows task analyses to be simulated on a computer to study dynamic system behavior through the addition of information, primarily task time and sequencing. A technique was developed by McCracken and Aldrich (1984) and modified by Drews, Laughery, Kramme, and Archer (1985) which permits the inclusion of workload information into a task network model. From these workload models one can make predictions about where points of excessive operator overload are likely to occur. However the technique has undergone only limited empirical validation. In addition to presenting the basic technique, this paper will briefly describe a software tool for using the technique as well as the perceived theoretical shortcomings of the technique in its current form.

Aerospace Systems: Simulation and Decision Aiding

The Effects of Visual Cues to Realism and Perceived Impact Point during Final Approach BIBA 115-119
  Woodrow Barfield; Craig Rosenberg; Conrad Kraft
This research investigated the effect of providing three different simulations of ground terrain on the ability of subjects to accurately determine the aimpoint during a final approach. Several simulations were created to model a straight-in final approach (3 degree glideslope) to a standard FAA runway from several distances. The three levels of terrain realism ranged from a homogeneous surface to farmlands with hills. The subject's task was to estimate the aimpoint which represented an extrapolation of the flightpath to its point-of-contact with the ground as well as the altitude at nine different distances from threshold. The results indicated that increased levels of realism lead to better performance in judging altitude and predicting aimpoint during a simulated final approach.
Comparison of Time Delay during In-Flight and Ground Simulation BIBA 120-123
  Valerie J. Gawron; Randall E. Bailey; Louis H. Knotts; Grant R. McMillan
An in-flight experiment was performed to investigate the effects of time delay on manual flight control and flying qualities. The experiment was conducted using the USAF/FDL variable-stability NT-33A aircraft. Pure time delay was added equally to the pitch and roll flight control system. Evaluation tasks were presented on a head-up display (HUD). Instrument meteorological conditions (IMC) were simulated which limited the visual cues available to the pilot to the 20 degree foveal scene provided by the HUD. The in-flight time delay data were generated with full fidelity, unlimited range of motion cues. Using the same cockpit and a digital aerodynamic simulation, the in-flight experiment was completely replicated as a fixed-based ground simulation. Thus, the effects of extreme conditions in motion cuing (i.e., full motion versus no-motion) were examined for constant visual cuing.
A General Model of Mixed-Initiative Human-Machine Systems BIBA 124-128
  Victor Riley
The increasing role of automation in human-machine systems requires modeling approaches which are flexible enough to systematically express a large range of automation levels and assist the exploration of a large range of automation issues. A General Model of Mixed-Initiative Human-Machine Systems is described, along with a corresponding automation taxonomy, which: provides a framework for representing human-machine systems over a wide range of complexity; forms the basis of a dynamic, pseudo-mathematical simulation of complex interrelationships between situational and cognitive factors operating in dynamic function allocation decisions; and can guide methodical investigations into the implications of decisions regarding system automation levels.
Constructing and Applying Cognitive Models to Mission Management Problems in Air Anti-Submarine Warfare BIBA 129-133
  Monica C. Zubritzky; Wayne W. Zachary; Joan M. Ryder
The ever-increasing capabilities of computers have resulted in a new generation of man-machine systems in which the machine acts in an intelligent manner to enhance the operator's decision-making capabilities in real-time multi-tasking (RTMT) situations. In such situations, the operator's information needs constantly change as he/she must attend to several events simultaneously and often switch from one decision-making task to another. The ability of the intelligent systems to aid humans in a flexible interactive fashion depends on the capability of the machine to predict these switches and the resulting changes in the human's information needs at a given time. These systems must therefore incorporate a model of the human operator's tasks based on information about the individual tasks and the dynamic relationships between the tasks and the occurrence of outside events. This paper focuses on the construction of such a model in the context of mission management problems of airborne Tactical Coordinators (TACCOs) in anti-submarine warfare (ASW). The model is built as a Cognitive Network of Tasks (COGNET) and is based on the integration of GOMS notation and the Blackboard architecture and is now being used to develop an adaptive intelligent interface for TACCOs.

Aerospace Systems: Space-Related Activities

Speech versus Manual Control of Camera Functions during a Telerobotic Task BIBA 134-138
  John M. Bierschwale; Carlos E. Sampaio; Mark A. Stuart; Randy L. Smith
Voice input for control of camera functions was investigated in this study. Objectives were to (1) assess the feasibility of a voice-commanded camera control system, and (2) identify factors that differ between voice and manual control of camera functions. Subjects participated in a remote manipulation task that required extensive camera-aided viewing. Each subject was exposed to two conditions, voice and manual input, with a counterbalanced administration order. Voice input was found to be significantly slower than manual input for this task. However, in terms of remote manipulator performance errors and subject preference, there was no difference between modalities. Voice control of continuous camera functions is not recommended. It is believed that the use of voice input for discrete functions, such as multiplexing or camera switching, could aid performance. Hybrid mixes of voice and manual input may provide the best use of both modalities. This report contributes to a better understanding of the issues that affect the design of an efficient human/telerobot interface.
The Effect of Pressure Suit Gloves on Hand Performance BIBA 139-143
  John M. O'Hara
The effects of pressure gloves on human hand capabilities is a major concern in the performance of extravehicular activity (EVA) for space maintenance and construction missions. The effects of EVA gloves on six hand performance domains was investigated in this NASA sponsored research. They were range of motion, strength, tactile perception, dexterity, fatigue, and comfort. All tests were designed to be performed in a glove box using the bare hand as well as the glove at 0 and 4.3 pressure differentials. Ten subjects participated in the test in a repeated measures design. The results of the experiments are summarized in this paper.
Usability Testing and Requirements Derivation for EMU-Compatible Electrical Connectors BIBA 144-148
  Ray A. Reaux; Thomas J. Griffin; Ruthan Lewis
On-orbit servicing of payloads is simplified when a spacecraft has been designed for serviceability. A key design criterion for a serviceable spacecraft is standardization of electrical connectors. The following research investigated the effects of extravehicular mobility unit (EMU) glove size, connector size, and connector type on usability of electrical connectors. An experiment was conducted exploring participants' ability to mate and demate connectors in an evacuated glovebox. Independent variables were two EMU glove-sizes, five connector size groups, and seven connector types. Significant differences in performance times and heart rate changes during mate and demate operations were found between EMU glove sizes, among connector types, and connector sizes. Subjective assessments of connectors were collected from participants with a usability questionnaire. The data were used to derive design recommendations for a National Aeronautics and Space Administration (NASA) recommended EMU-compatible electrical connector.
Neutral Buoyancy Methodology for Studying Satellite Servicing EVA Crewmember Interfaces BIBA 149-153
  Mary E. Barnby; Thomas J. Griffin; Ruthan Lewis
Current economic constraints indicate the need for incorporating the satellite servicing philosophy of commonality within the design of spacecraft subsystems. This philosophy is essential for conserving resources including hardware/software development and implementation costs, on-orbit ground-based manpower, crew training/testing time, and documentation. In addition, spacecraft subsystem commonality may be coupled with standardization of operational procedures, and test and verification technique for spacecraft design. Several spacecraft have adapted this practice, including Hubble Space Telescope, Space Station Freedom, and the Explorer Platform. As these and other programs continue and if effective crew interfaces and procedures are clearly and consistently defined, crew retraining for similar spacecraft subsystems will lessen, and procurement efforts will diminish. A relatively high fidelity zero-gravity simulation using water immersion is available to establish crew interfaces economically. The flexibility and utility of this space simulation medium for planning and assisting on-orbit operations was exemplified by astronaut evaluations of potential extravehicular activity electrical connectors. The testing was conducted at a National Aeronautics and Space Administration underwater neutral buoyancy training facility.

Aging: Older People and New Cars

Older Drivers' Visibility and Comfort in Night Driving: Vehicle Design Factors BIBA 154-158
  Rudolf G. Mortimer
Older persons are a growing proportion in the population, among drivers and those involved in traffic accidents. Changes in visual abilities of older persons are pertinent to night driving glare. Vehicle headlighting and related factors are reviewed which affect visibility and comfort in night driving. Older drivers, in particular, would be aided at night by: increasing the reflectivity of objects, limiting the mounting height of headlamps, appropriate reflectivities of mirrors for control of glare, automatic headlamp alignment, automatic headlamp cleaning and beam patterns that emphasize glare control.
Age-Related Decrements in Automobile Instrument Panel Task Performance BIBA 159-163
  Brian C. Hayes; Ko Kurokawa; Walter W. Wierwille
This research was undertaken, in part, to determine the magnitudes of performance decrements associated with automotive instrument panel tasks as a function of driver age. Driver eye scanning and dwell time measures and task completion measures were collected while 24 drivers aged 18 to 72 performed a variety of instrument panel tasks as each drove an instrumented vehicle along preselected routes. The results indicated a monotonically increasing relationship between driver age and task completion time and the number of glances to the instrument panel. Mean glance dwell times, either to the roadway or the instrument, were not significantly different among the various age groups. The nature of these differences for the various task categories used in the present study was examined.
Factors to Consider when Designing Vehicles for Older Drivers BIBA 164-168
  Anthony J. Yanik
As the Baby Boom generation gradually moves into its later years, that movement will become a Senior Boom that will have a dramatic effect upon the design of products entering the marketplace. To respond to this market, engineers and designers will require a good understanding and awareness of the changes that take place in vision and cognition as a result of the aging process, and how these changes affect the interaction of older adults with their vehicle systems such as controls and displays, mirrors, entry and exit, and lighting. This paper is an attempt to bring that understanding to the designer and engineer, as based upon current research.

Aging: Performance and Cognition in Older Persons

Arithmetic Stroop Interference as a Function of Age: Maintenance and Modification of Automatic Processes BIBA 169-173
  Wendy A. Rogers; Arthur D. Fisk
This experiment investigated whether well-learned "automatic" processes remain stable as a function of age, as well as whether the ability to modify automatic processes is disrupted for older adults. We used an arithmetic "Stroop" task. Nineteen young (mean 22) and 19 old adults (mean 75) participated in three sessions for a total of 450 trails. The young subjects had faster verification times, overall, than the old adults. Both young and old subjects showed significant Stroop interference. These results support the hypothesis that automatic processes, in this case access of addition and multiplication tables, are maintained for old adults. Furthermore, both groups reduced their RT with practice. For the young adults, there was a decrease in interference with practice suggesting that they were learning to inhibit the automatic process of performing the arithmetical operation. However, the old adults showed no significant decrease in interference, which implies that they were impaired in their ability to inhibit automatic processes, even when those processes interfered with performance. Theoretical and practical training implications are discussed.
Aging, Reaction Time, and Stages of Information Processing BIBA 174-178
  Max Vercruyssen; Barbara L. Carlton; Virginia Diggles-Buckles
Using Sternberg's (1969) Additive Factors Method (AFM), previous investigations in search of the locus of age-related slowing in reactive capacity have found conflicting results possibly due to inconsistencies in research methodologies. This experiment was conducted to examine age differences in the performance of AFM intratask manipulations of a reaction time task using both fixed and variable foreperiod conditions with subject testing at both naive and practiced skill levels. Twenty male subjects, ten young and ten old, performed a visual four-choice RT task with intratask manipulations of stimulus-degradation, stimulus-response compatibility, and response-stimulus intervals (RSIs were fixed at 0, 2, and 5 sec and variable with random presentations at 0, 2, and 5 sec), once when subjects were naive and again when practiced. The results varied by level of practice and RSI, but clearly the older subjects had difficulty with the intratask manipulations. The older subjects took twice as long, on the average, to respond. Interactions of age by compatibility suggest that, according to the AFM, with age comes inordinately long delays in the response selection stage of information processing. Conclusions are made with caution since this research points to limitations and methodological confounds which serve to explain many of the equivocal findings in previous studies.
A Comparative Study of Text-Editing Programs among a Sample of Older Adults BIBA 179-181
  Sara J. Czaja; J. Bonnie Joyce; Katka Hammond
Research indicates that older adults have difficulty acquiring text-editing skills. The data suggest that the cognitive demands associated with text-editing programs create problems for older learners given the age-related changes in cognitive abilities. This study compared the learning efficiency of older adults for three text-editing programs which varied in format and command structure. A total of 45, computer naive, women ranging in age from 40 to 70 years participated. The results indicated significant differences in learning efficiency as a function of text-editing program. Participants using a full screen editor with pull down menus demonstrated significantly better performance than did those using other programs. Data was also collected regarding types of difficulties encountered by subjects during learning. This type of information can be used as input into the design of future software and training programs.
Activities of Daily Living of the Elders -- A Task-Analytic Approach BIBA 182-186
  Ruth Weber; Sara Czaja; Ram Bishu
Human factors research, which focuses on matching human capabilities and limitations with different environmental and task demands, has been wanting in the areas of elderly population. The main objective of this research was to use a task analytic approach to identify the demand profiles for a list of daily activities of the elderly. Sixty-six independently living elderly persons were videotaped performing 25 separate activities of daily. A computerized task analytic approach was used to analyze the activities. Tasks were described through a set of descriptors such as action (e.g., reposition), demand (e.g., carry), object (e.g., broom), body part (e.g., hand), posture (e.g., bend), location (e.g., wash room) and frequency. Crosstabulations were performed on the data to determine pattern of relationships amongst the various task descriptors, both within, and between activities. In terms of demands, few activities account for a large proportion. Lifting/lowering, push/pull appear to be the predominant actions. Relationship among task, posture, body part and demands were significant.

Aging: Environments, Products, and Technologies for the Aging Population

Gerontechnology, The Modelling of Normal Aging BIBA 187-190
  Jan A. M. Graafmans; Tonny Brouwers
Demographics announce the rise of an array of small and bigger challenges, which cannot be taken up adequately by a single research discipline, industrial branch or central administration. The segregation and segmentation of our society causes limiting conditions in facing the most substantial and acute societal problems. The complexity and versatility of these problems require a policy that has to be conceptualized. The concept "gerontechnology" is introduced to cover and provide some coherent elements in order to establish a strategy, that is aiming at an efficient and effective use of essential resources, to match developments induced by an aging population. Normal aging processes can be described within this concept using the man-machine-environment interaction model that is loaded with sets of variables that are characteristic for an aging human function. Sets of variables are distinguished at three levels with increasing complexity from basic research on parameters of aging, via human factors research on grey human factors, to market research on daily consumer needs of the elderly. Two projects are presented as examples of respectively an industrial and a basic research approach in this domain.
The Study of Home Safety Problems for Older Disabled Persons: A Multi-Dimensional Approach BIBA 191-193
  J. Watzke; D. B. D. Smith; N. Somerville; A. Verran
The presentation features beginning efforts on a 5 year project concerned with the identification of home safety problems and technological solutions for older disabled persons. First, the multi-dimensional model guiding the project is presented. Second, pilot survey data concerned with 72 older persons' home accident histories, risk perceptions associated with everyday activities, and tendencies to engage in risky in-home behaviors are discussed. Finally, preliminary survey data from 30 "in-home assessment" professionals will be discussed. These data identify environmental, functional, and psychological in-home safety problems for elderly persons for the given daily activities stipulated by the project's model.
Dysphagia: New Technologies in Aging BIBA 194-198
  Allen Boysen; Paul Haber
The normal process of swallowing is an extremely complicated and highly integrated process, only part of which is under voluntary control. The normal process of swallowing requires that the neuromuscular structure, the cartilaginous and bony elements and their innervation will be intact. A number of high technology and semi-technology procedures have been developed which will help elucidate the cause of the swallowing problem. These include: videofluoroscopy, scintigraphy, manometry, fiberoptic endos-copy, ultra-sound, and clinical auscultation. A deglutition team consisting of otolaryngologist, neurologist, speech-language pathologist, radiologist, nurse practitioner, and dietitian can have a major impact on determining the cause of the swallowing difficulty and correcting it.

Aging: Panel

Human Factors Research on Aging: An International Perspective from Canada and Europe BIBA 199
  David B. D. Smith; Betty Ann Raschko; Stuart Kirk; I. A. R. Galer; Claude Gidman
Most populations of the world are aging. In developed countries the older population will double in the next 30 years; in underdeveloped countries it is expected to quadruple. This has led to world wide interest in the application of human factors to problems of aging (Smith, 1988). The purpose of this panel is to bring a perspective on research and design from outside the U.S.

Communication: Communications Case Studies

Evaluation of Mobile Telecommunication Systems BIBA 205-209
  Demetrios Karis; Bonnie L. Zeigler
Mobile telephony exhibits transmission characteristics and user-interface features distinct from traditional telephony. To study these differences in systems designed for use in commercial airplanes, trains, and automobiles, we used a variety of techniques, including both laboratory and field observations. We found that mobile telephony, viewed from the user's perspective, is quite different from traditional telephone service. In the present paper, we review the assessment techniques that we employed, and consider their strengths and weaknesses for characterizing the performance of mobile telecommunication systems. Our results indicate that there are five major sources of potential user-interface problems in mobile telephony: (1) use of credit cards; (2) system delays; (3) lack of coordination among multiple sources of feedback; (4) the mechanism for completing multiple calls without credit-card reentry; (5) voice dialing. Because solving the problems we have identified does not require new or overly expensive technology, solutions are fairly straightforward to implement during the early design period. However, once units have been manufactured and installed, it can be both very difficult and very expensive to recover from the problems we have identified.
Human Factors Considerations in the Design of Trader Turrets for the New York Stock Exchange BIBA 210-214
  Paul Roller Michaelis
This paper describes the Human Factors evaluation of a new generation of trader turret, a highly specialized telephone used by brokers on the floor of the New York Stock Exchange. The evaluation consisted of three parts: (1) environmental and acoustical studies at the New York Stock Exchange, (2) job analyses, task analyses, and interviews that helped designers determine and satisfy the brokers' needs, and (3) laboratory experiments at Bell Labs in Holmdel that evaluated alternative designs and features.
Analysis of Network and System Management Tasks BIBA 215-218
  Brenda M. Scott
Network and system management tasks revolve around the activities necessary to establish and maintain data communication networks. This can include tasks such as:
  • monitoring the network hardware and software components for problems and
       performance information
  • identifying and correcting problems in the network
  • planning and making changes to the network Task analysis was performed on data available from a customer case study database (Beith, Moore, Pendley, and Percival, 1985). Models were developed for several network and system management tasks. This paper discusses one of the task models, problem determination, and presents recommendations for information structuring and task flow.
  • Communication: Methods for Interface Design

    A Living Systems Theory Approach to Human-Computer Interface Design BIBA 219-223
      Martin J. Abbott
    This paper presents Living Systems Theory (Miller, 1978) as a conceptual framework for human-computer interface (HCI) design. Many researchers and practitioners in the field of HCI design have used systems terms and concepts in their work; however, it is not clear that an integrated systems approach has been taken in the field of HCI design. Living Systems Theory (LST) is proposed as the means for obtaining a conceptual framework for the study of the HCI. Miller clearly defines terms and concepts that can serve as a "common language" to improve communication within and across disciplines. It is likely that a multidisciplinary field such as HCI design could benefit from LST. Specifically, by adopting this "common language", researchers and practitioners in the field of HCI could improve communication with other disciplines which could facilitate the sharing of information across disciplines.
    What Can You Learn from a Low-Fidelity Prototype? BIBA 224-228
      Robert A. Virzi
    A case is made tor using low-fidelity prototypes early in the design phase of new services. The rationale for this is based upon (1) a model of how user interface designs progress and (2) a call to expediency. The design process is viewed as the successive application of constraints that serve to prune the space of all user interfaces. Some constraints are external (i.e., placed on the service by limits of technology or cost). Other constraints are derived by application of heuristic design principles. Even after these constraints have been applied, the design is still not fully constrained and the designer must make high-level design decisions. At these choice points, I propose that low-fidelity prototyping is an appropriate means of gathering design information as it is an expedient solution and may serve as a method of testing the central tendency of entire classes of user interfaces.

    Communication: Language Processing and Voice Interfaces

    When "Not" is Not Bad: A Re-Evaluation of the Use of Negatives BIBA 229-233
      Sandra L. Newsome; Michael E. Hochlerin
    Previous literature has consistently shown that affirmative messages are understood more quickly and accurately than negative messages and that redundancy facilitates comprehension and response selection. However, it was unclear which of these two variables is the most important in the design of system-status messages that must be understood and acted upon. In our experiment, we compared affirmative and negative system-status messages when negative messages contained a word redundant with the appropriate action. The results indicated that affirmative messages were responded to more quickly and more accurately than negative messages only when the negative messages did not contain a redundant word. Redundant negative messages were more accurate than affirmative non-redundant messages.
    Evaluation of Audio Response Time Delay Requirements for Digitized Audio BIBA 234-238
      Paula M. Van Balen; Leslie R. Eisler
    As digital voice data is increasingly replacing analog in system applications, user interface requirements supporting this technology must be established. This experiment was conducted to determine whether system response time affected a user's ability to control movement of recorded speech while keying in a verbatim report of the speech content. Experienced subjects performed a transcription task under four different response times. Upon completion of the task, the subject ordered the response times from shortest to longest and rank-ordered their preferences for response delay times. Performance data was collected to discover if response time differences affected performance.
       Subjects were unable to identify the response time delays correctly; and, based on the preference rankings, the subjects were most satisfied with a response time delay range between 100 ms and 150 ms and least satisfied with a response time delay of 250 ms. Subjects stated that with the longest and shortest response time delays they had trouble positioning in the audio. Response time delays did not affect subject performance, although other significant results were found.
    Short-Term Memory Demands in Processing Synthetic Speech BIBA 239-241
      Margaret Thomas; Richard Gilson; Sharon Ziulkowski; Stephen Gibbons
    The purpose of the present experiment was to investigate the demands placed on the short term memory system by synthetic speech. We compared performance in a typical auditory short term memory task as a function of whether the items were presented by a human voice or by a text-to-speech computer voice generator. Immediate serial recall of digit strings was significantly poorer when presented by synthetic speech than when presented by natural speech. The results are consistent with the idea that comprehension of synthetic speech imposes increased resource demands on the short term memory system.

    Computer Systems: Panel

    Current Research in the Psychology of Programming BIBA 242-244
      Michael E. Atwood; Ruven Brooks; Wayne D. Gray; Raymonde Guindon; Thomas W. Mastaglio
    Computer programming is one of the earliest topics addressed by studies of the human factors of computer systems and studies of how software systems are developed remain one of the most difficult areas of investigation. Early work in the psychology of programming focused on comparisons of time-sharing and batch modes, studies of programming team organization, studies of debugging, and investigations of the differences between novice and expert programmers. As new theories and experimental methodologies were developed, further areas were researched.
       This panel looks at current research in the psychology of computer programming. Topics include studies of programmer behavior, studies of software design, tools for programmers, and experimental methods. Audience members will have an opportunity to describe other areas of study.

    Computer Systems: Tools for User Interface Design

    ITS: A New Method for Computer Application Development and Prototyping BIBA 245-248
      John D. Gould; Stephen J. Boies; Sharon L. Greene; William Bennett
    Perhaps the one thing that user interface designers most want is tools that will help them (a) quickly visualize their work; (b) carry it out more efficiently and faster; and (c) do iterative design; and (d) allow them to do more work without the need of programmers. An on-going research project (called ITS) is responding to these challenges by developing software tools for user interface and application development, together with providing a run-time environment for application execution. There are four key concepts. First, ITS separates the style of an application from the content of an application. Human-computer interface styles are general, rule-based, under parameter control, and designed to handle a variety of applications. Second, ITS envisions four general work roles in application design and development: content experts, content programmers, style experts, and style programmers. Third, end users do four operations: make choices, fill in forms, manipulate lists, and read information blocks. Fourth, ITS aims at creating software tools for each work role.
    ProtoTymer: Human Performance Instrumentation for HyperCard Prototyping BIBA 249-253
      Dwight P. Miller; Andrew C. Stone
    As a result of the popularity of using HyperCard to rapidly prototype equipment and computer interfaces on Macintosh personal computers, the need ensued to evaluate prototype usability by collecting subjects' interactive performance data in real time. Sandia National Laboratories, in collaboration with Stone Design Software, has developed ProtoTymer, a HyperCard stack that can time and record users' interactive sessions with prototypes developed using HyperCard. While operating in the background, ProtoTymer records the times, locations, and targets (objects clicked) of a subject's inputs during an interactive session. At the conclusion of the session, the resultant data file can be reviewed, summarized, printed, or transferred to a spreadsheet for statistical or graphical analysis. This paper describes ProtoTymer's design approach, features, limitations, and considerations for future versions.
    Using Databases in the Design of User Interfaces for Complex Systems BIBA 254-258
      Donald M. Allen; Daniel T. Donohoo; William H. Muto
    Because of the increasing complexity and size of systems for which user interfaces must be designed, manual analysis of user and system requirements are inadequate. Methods for employing database tools in top down design strategies have been developed to manage design information in the development of user interfaces for large and complex systems. These methods have been useful in the design of user interfaces that are internally consistent with the user's model of the system and that are consistent across related software applications.
    Towards a Generic Strategy for Empirical Evaluation of Interactive Computing Systems BIBA 259-263
      Thomas T. Hewett
    Increasingly, the design of interactive computing systems appears to be a process of iterative design and re-design. One important factor in successful iterative design is iterative evaluation -- evaluation as part of each design cycle. This paper argues that different evaluation-design cycles may require different types of methodologies and different types of questions or measures to fully satisfy differing evaluation goals. Furthermore, evaluation procedures and measures themselves need to be designed and re-designed, a process more easily accomplished during system development. Examples based upon design projects illustrate some of the ways in which the nature and uses of evaluation procedures and information may change in different cycles of iterative evaluation.

    Computer Systems: Approaches to User Interface Design

    Development and Testing of an Evaluation Procedure for User Interface Management Systems (UIMS) BIBA 264-267
      Deborah Hix; Kay C. Tan; Robert S. Schulman
    A user interface management system of UIMS is an interactive system for supporting the design, production, and execution of human-computer interfaces. This paper reports on the development and empirical testing of an evaluation procedure to produce quantifiable criteria for evaluating and comparing UIMS. The form-based evaluation procedure results in quantitative ratings along two dimensions: functionality and usability. Specification/implementation techniques used by a UIMS are also quantitatively rated. An empirical study has indicated that the procedure produces reliable, useful results.
    Iterative Tutorial Design in the Product Development Cycle BIBA 268-272
      Ronald Perkins; Louis A. Blatt; Daniel Workman; Susan F. Ehrlich
    Early development of a tutorial fostered a joint effort between human factors professionals, software developers and training consultants that resulted in early resolution of many problems during the development of Wang Freestyle, a new multimedia communication system. It was decided that new users of Freestyle should be able to use the basic annotation features without referring to any hardcopy documentation. To ensure this, iterative tests of evolving prototypes of (1) the software and (2) an on-line tutorial that was designed to teach any features of the system that were not immediately intuitive were carried out. Changes were made in the software and the tutorial, resulting in improvements to both. The methods used and some of the lessons learned from this initial experience with iterative tutorial development are discussed.
    Iterative Usability Testing of a Security Application BIBA 273-277
      Clare-Marie Karat
    This paper reports the results of three iterative usability tests of a security application as it evolved through the application development process and highlights the use of several methodological techniques: 1) reusable color foil prototypes of application panels as an alternative to developing online prototypes during short development cycles, 2) field tests as a complement to laboratory tests, 3) iterative testing of an evolving prototype, and 4) analysis of dollar value of usability work. The techniques used represent an attempt to apply usability engineering to system design (Whiteside, Bennett, and Holtzblatt; 1988) and to provide management with a dollar value estimate of human factors work (Mantei, 1988). Significant improvements in end user performance and satisfaction occurred across the three iterative tests (field prototype test, laboratory prototype test, and laboratory integration test) conducted across 7 months with 27 participants. The product usability objective was met during the third test. By using the reusable foil prototypes of the interface panels, usability staff were able to efficiently and effectively identify problems, make design changes, and retest the panels. The field test furnished unique data necessary to understanding end user issues. Iterative testing provided the opportunity to test the impact of changes made to the interface and a reliability check on previous results. The methodology for computing the value of usability work provided a feasible way of analyzing the cost benefit of the human factors work.

    Computer Systems: Panel

    Theoretical Models for System Design BIBA 278-280
      Michael E. Atwood; Gerhard Fischer; Wayne D. Gray; Peter G. Polson
    In the history of human factors in computer systems, one of the most significant events of the past decade was the work on GOMS and keystroke models (cf. Card, Moran, and Newell, 1983). While a clear success in causing software developers to focus on the importance of interface design and attracting researchers to this areas, GOMS approaches have not significantly improved the quality of the systems that are developed.
       Why has this work, that has a great theoretical impact, had so little practical impact on existing systems? Is it that the GOMS formalism is not valid outside of laboratory contexts? Is it that it misses important aspects of behavior such as how people learn to use systems? Is it that GOMS was developed in the context of computer systems that are less powerful and interactive than we have today? Or, are there other reasons?
       In this panel, we argue that additional cognitive science approaches are needed to improve the quality of developed system. Dr. Gray extends this approach by reporting the first "real world": test of the GOMS-style of system modeling. Dr. Polson extends these models to how people learn to use systems. Dr. Fischer extends this style of research by focusing on cooperative, rather than passive computer systems. Audience members will have an opportunity to describe other approaches to developing theoretical models of system design.

    Computer Systems: Modeling

    Designing Help Systems Using the GOMS Model: An Information Retrieval Evaluation BIBA 281-285
      Jay Elkerton; Susan Palmiter
    Using the GOMS model (Card, Moran, and Newell, 1983), a help system was developed which was complete and well structured. The content of this help system was determined from the goals, operators, methods, and selection rules needed to perform HyperCard authoring tasks. The index to these methods, which was an integrated part of the system, was determined from the hierarchical goal tree provided by the GOMS analysis. To determine the effectiveness of using GOMS as a design aid for help systems, the GOMS help system was compared to a state-of-the art interface developed by Apple Computer which was modified slightly for experimental purposes (Original help system). Two groups of 14 users, using one of the two help systems, retrieved help information about 56 tasks separated into 4 sessions. The results indicated that the GOMS users were significantly faster than the Original users with the largest speed difference occurring in the first session. However, no reliable differences were found for retrieval accuracy between the two groups. This is not surprising since the Original help system was found to have 85.9% of the procedural information contained in the GOMS help system. Interestingly, participants subjectively rated the GOMS help system higher than the Original help system. Overall, the results from this information retrieval study suggest that a GOMS model can aid in the development of help systems which are easy to use, easy to learn, and well liked.
    A Context-Based Model of Attention Switching in Computer-Human Interaction Domains BIBA 286-290
      Wayne Zachary
    COGNET (Cognitive Network of Tasks) is a model-building framework for real-time attention sharing cognitive processes. It is particularly designed for the construction of computational models of human-computer interaction. COGNET is unique in that it leads to context-sensitive models of attention switching based on the human operator knowledge of the real-world domain being modeled. A COGNET model combines an augmented version of the GOMS task analysis language with the blackboard architecture of control. This paper discusses the theoretical organization of the COGNET framework, as well as the augmented GOMS/blackboard tools used to build COGNET models.
    Operator Models for Supervisory Control Systems BIBA 291-295
      Patricia M. Jones; Christine M. Mitchell
    This paper presents a conceptual discussion of four human operator models that are potentially useful for supervisory control applications: the operator function model (Mitchell, 1987), the problem behavior graph (Newell and Simon, 1972), the decision ladder (Rasmussen, 1986), and goal-means network (Woods and Hollnagel, 1987). These models are characterized along the dimensions proposed by Jones and Mitchell (1987) and are further examined in-depth with the use of verbal protocols collected concurrently with the performance of a supervisory control task.

    Computer Systems: Speech and Writing

    Evaluating the Accuracy of a Large-Vocabulary Speech Recognition System BIBA 296-300
      Norman R. Brown; Ann Marie Vosburgh
    The Tangora is a large-vocabulary, speaker-dependent, isolated-word speech recognition system. In this paper, we describe a study designed to test this system under a broader range of conditions than had previously been considered. The experiment itself consisted of four experimental sessions: Sessions 1 and 4 were enrollment sessions, and Sessions 2 and 3 were test sessions. During each test session, participants read 32 preselected sentences and dictated 40 sentences of their own composition The results of this experiment indicated that (a) there was a high degree of inter-subject variability and a high degree of intra-subject consistency; (b) users did not improve with limited experience; (c) the style/content of the test sentences affected recognition performance; (d) recognition errors were more common following misrecognized words than following correctly recognized words; and (e) new users had little difficulty with isolated-word speech. We discuss the implications that these findings have for application selection, interface design, user training, and system evaluation.
    Developing Successful Speakers for an Automatic Speech Recognition System BIBA 301-304
      Catalina M. Danis
    This paper reports on a study of recognition performance for a group of new users during their first month of experience with the Tangora systems. Tangora is a 20,000 work, speaker dependent, isolated-word system which transcribes speech input into text in real-time. Twelve users, six males and six females, participated in 21 sessions each, during which they read aloud unrelated sentences selected from a corpus of office correspondence. Their goal was to develop a speaking style which minimized Tangora's recognition error. To this end, starting with the third session, the experimenter generated hypotheses about each users' speech habits which may have resulted in high recognition error and made suggestions to the user on how to modify his/her speaking style. In addition, each user produced a new speech sample each of the four weeks of the experiment which was used to "train" the system to recognize the speaker. On average, recognition error decreased by 33% from the first to the fourth week. This improvement was attributable to "retraining" the system with, apparently, more representative speech samples. A number of speech habits brought by users to the recognition task were identified as contributing to poor recognition performance by Tangora. These included: (a) a too fast speech rate, (b) failure to pause between words, (c) hyper-correct articulation of the final phoneme in words. Feedback relating to these speech habits was used successfully by a majority of the users to modify their speaking style into one more successfully recognized by the Tangora system.
    Handprinted Data Entry with a Touch-Sensitive Numeric Keypad BIBA 305-309
      Georg Geiser
    A new method for hand printed data entry is proposed for those user tasks where only few characters have to be entered. The basic idea is to use a numeric keypad as writing surface for one finger. For this purpose the keys are equipped with touch sensors, and display elements are fitted to the keys and the intermediate spaces. By means of the arrangement of the keys in the keypad the writing surface has a structure of rows and columns which motivates the user to produce characters with a standard format and uniform line elements. In order to allow characters to be sloppily written to some extent, the method of dynamic programming was applied for a nonlinear adaptation of pattern and prototype vectors. A first series of experiments showed that error rates of the subjects (e.g. omissions, confusions) and of the pattern recognition system (errors, rejections) are very low.
    An Investigation of Techniques for Occasional Numeric Data Entry BIBA 310-314
      Joel S. Greenstein; Anish Baijal
    This work tested six techniques for the occasional entry of unstructured numeric data in the context of a primarily mouse-based, cursor-positioning, human-computer dialogue. Two of the techniques used a separate keypad for numeric data entry. The other four techniques used the mouse already being used for the cursor positioning dialogue. The keypad techniques were more efficient than the mouse techniques for all of the numeric sequence lengths considered. There were no significant differences in efficiency between the two keypad techniques. Among the mouse-based techniques, an approach based on a displayed image of a calculator keypad was consistently among the most efficient.

    Computer Systems: Touch and Gesture

    An Experimental Determination of Human Hand Accuracy with a DataGlove BIBA 315-319
      David L. Quam; George B. Williams; Jeffery R. Agnew; Patricia C. Browne
    A three-part experiment was conducted to determine the accuracy, repeatability and linearity of a human hand manipulating the DataGlove. Accuracy and repeatability of finger flexure were investigated with repeated measurements of three calibration positions. Linearity of finger flexure was investigated with steady finger and thumb curling motions. Accuracy and repeatability of hand location and orientation were investigated with repeated measurements of six hand positions. Finger flexure mean accuracy was 6° for the four fingers and 11° for the thumb, repeatability was 3° for the four fingers and 9° for the thumb, and linearity varied from 2 to 5°. Although the mean location accuracy was 1 inch and the mean orientation accuracy was 17°, the position and orientation receiver was observed to twist on the glove back. Across all subjects, the location repeatability was 0.5 inch, while the orientation repeatability was 9°. However, the within-subject location repeatability was 0.13 inches, while the orientation repeatability was 2°.
    Operator Behavioral Biases Using High-Resolution Touch Input Devices BIBA 320-322
      Dennis B. Beringer; Mary James Bowman
    Real-world applications of touch-input technology often do not occur under ideal conditions. Users often must contend with off-axis viewing and non-optimal positioning, introducing the possibility of vertical or horizontal bias error. In the present study the effects of screen angle relative to line of sight and positioning of targets were examined with a high-resolution (1 pixel or about 1/12 mm) resistive touch input device thought to have minimal parallax. Results replicated earlier findings of Beringer & Peterson (1985) in that a 17-degree declination of the touch surface below orthogonal to line of sight induced a high-touch bias error of 9 pixels (about 3/4 mm) whereas orthogonality of the interface to line of sight virtually eliminated bias. Both software and behavioral compensation strategies are discussed.

    Computer Systems: Panel

    Visual Interface Design BIBA 323-324
      Evelyn Williams; Eliot Tarlin; Barry Mathis; David Dawson; Annette Wagner; Marsh Chamberlain
    User interface design has many components. Usable computer interfaces should be easy to learn, result in high user productivity and high user satisfaction. There are a number of components in user interface design that affect the usability of the interface. Within the human factors community we tend to emphasize the ergonomic and cognitive components of the computer interface. There is another component that is frequently ignored, the visual interface design. This panel will present information on the visual component in various user-computer interfaces and will discuss the contributions of the visual designer to the interfaces and usability.

    Computer Systems: Input Device Comparisons

    A Benchmark Comparison of Mouse and Touch Interface Techniques for an Intelligent Workstation Windowing Environment BIBA 325-329
      Robert Mack; Kathy Lang
    This study presents evidence that a prototype touch interface technology emulating basic interaction techniques of a mouse pointing device is comparable in overall usability to a conventional mouse for a direct manipulation, graphical windowing software environment. The touch technology prototype involves using either a stylus or finger, with an overlay sensitive to changes in capacitance. Users practiced each technique (mouse, stylus, finger, keyboard with no mouse), in the context of carrying out office-related tasks on the first of a two day study, and then eight similar test tasks on the second day, in a completely within-subject design. Significant effects for time on task were found for Techniques and Tasks for five practice tasks on the second day of the study. The clearest significant effect was that the stylus technique was faster than the keyboard. A qualitative analysis of errors indicates that there were problems with the precision of pointing using the finger, and to a lesser extent the stylus and mouse. User comments and ratings indicate that the stylus and mouse were preferred comparably, and were preferred to the finger and keyboard techniques.
    A Comparison of Computer Input Devices: Linus Pen, Mouse, Cursor Keys and Keyboard BIBA 330-334
      Karen Renee Mahach
    Four input devices were compared in a data entry task by speed and accuracy scores. The input devices were: Linus pen (a handwriting recognition system), optical mouse, cursor keys, and alphabetic keys on a keyboard. Data entry consisted of twenty 5-letter words and 100 single letters. Two different screen designs (QWERTY and ALPHA) were used for the mouse and cursor keys conditions. Results showed the keyboard to be fastest and the cursor keys to be slowest in data entry. The mouse and Linus pen had comparable latency scores. Overall, five-letter words were entered faster than five single letters. Latency decreased over trials, and ALPHA conditions required more time than QWERTY conditions. The Linus pen was the least accurate input device. The cursor QWERTY condition produced the highest accuracy scores for letter entry while the keyboard produced the highest accuracy scores for word entry.
    An Expert System for the Selection of Input Devices BIBA 335-339
      Jurine Adolf
    This research effort consisted of the development and implementation of a user interface model in an expert system. The model, User-Input Device Model (UIDM), was composed of three parts: user, device, and task components. The expert system, Input Device Selection Assistant (IDSA), applied primary and secondary measures of ergonomic criteria on combinations of the UIDM components to develop a knowledge base for the selection of an input device. Personal Consultant Plus provided the inference engine to determine the most appropriate device. Results of experimentation and experience taken from human factors literature composed the expertise.

    Computer Systems: Applications of Computer Systems

    A User Interface for a Battlefield Distributed Information System BIBA 340-344
      Floyd Glenn; James Hicinbothom; Stanley Schwartz; Ken Smith; Eric Heilman
    This effort was conducted to redesign and improve the user interface for the Distributed Fact Base (DFB) component of the Army's Smart Weapon System / Information Distribution System (SWS/IDS), which is being initially developed to support battlefield fire control for fighting echelons up to the brigade level. The SWS/IDS consists of multiple clusters of powerful workstations that are networked together over low-speed radio links. The IDS manages the efficient updating and interrogating of nodes of the DFB so as to maximize system performance within communication channel capacity limits, thereby minimizing the amount of information exchange among battlefield units. The user interfaces address the distributed character of both the information and the decision processes as well as the essential complexity of the knowledge domain. Interface design is being accomplished using a general design methodology for distributed intelligent systems that entails systematic consideration of system and user objectives, cognitive capabilities and limitations of the user, and available technology options. An object-oriented approach was used for developing an enhanced interface for map, chart, and list applications using newly devised interface design tools known as Object-Action Specification Tables (OASTs) and an Object-Action Specification Language (OASL). The OASTs are tables that indicate which actions can be performed on which display and control objects and which control objects can perform which actions on other objects. Wherever an object-action combination is feasible, an entry in OASL indicates how the action is accomplished (e.g., by selection of pull-right menu item; mouse-button click with mouse cursor on screen icon; etc.).
    Use of Computer Graphics and Cluster Analysis in Aiding Relational Judgment BIBA 345-349
      Yili Liu
    An experiment is conducted to investigate the use of computer graphics and cluster analysis in aiding human relational judgment. The experimental stimuli were similarity matrices from real-world data sources. The experimental tasks required the subjects to detect the number of clusters or to judge the similarity value between a designated pair of objects in the displayed matrix. Each matrix was either ordered randomly or arranged according to the results of cluster analysis. Each matrix was displayed in one of four schemes: number scheme, color scheme, size scheme or 3-D vertical line scheme. The results indicated that the cluster-ordered displays greatly facilitated cluster detection performance in three out of the four display schemes, with the 3-D line scheme as the only exception. Matrix ordering had no effect on the value judgment task. The proximity compatibility principle (Wickens, 1987) and theories of perceptual grouping (Garner, 1976; Pomerantz, 1981) provided predictions and were tested in this experiment. Theoretical and practical implications were also discussed.

    Computer Systems: Formulation of Expert System Knowledge

    Formulation of Expert System Knowledge BIBA 350
      Deborah A. Mitta
    Expert system knowledge represents expertise obtained through formal education, training, and/or experience. Formal education provides deep knowledge of a particular domain; experience and training result in heuristic knowledge. A knowledge base defines the range of information and understanding with which the system is capable of dealing; therefore, its information must be structured and filed for ready access. The objective of this symposium is to address the challenges associated with establishment of valid expert system knowledge, specifically, knowledge to be used by expert system shells. As expert system knowledge is obtained, structured, and stored, it is formulated. In this symposium, knowledge formulation is addressed as a three-phase process: knowledge acquisition, the mechanics associated with structuring knowledge, and knowledge porting.
       Knowledge acquisition is the process of extracting expertise from a domain expert. Expertise may be collected through a series of interviews between the expert and a knowledge engineer or through sessions the expert holds with an automated knowledge acquisition tool. Thus, the ultimate outcome of knowledge acquisition is a collection of raw knowledge data. The following human factors issues become apparent: documenting mental models (where mental models are the expert's conceptualization of a problem), recording cognitive problem-solving strategies, and specifying an appropriate interface between the domain expert and the acquisition methodology. The knowledge structuring process involves the refinement of raw knowledge data, where knowledge is organized and assigned a semantic structure. One issue that must be considered is how to interpret knowledge data such that formal definitions, logical relationships, and facts can be established. Finally, formulation involves knowledge porting, that is, the movement of an expert system shell's knowledge base to various other shells. The outcome of this process is a portable knowledge base, where the challenges lie in maintaining consistent knowledge, understanding the constraints inherent to a shell (the shell's ability to incorporate all relevant knowledge), and designing an acceptable user-expert system interface.
       The fundamental component of any expert system is its knowledge base. The issues to be presented in this symposium are important because they address three processes that are critical to the development of a knowledge base. In addition to presenting computer science challenges, knowledge base formulation also presents human factors challenges, for example, understanding cognitive problem-solving processes, representing uncertain information, and defining human-expert system interface problems. This symposium will provide a forum for discussion of both types of challenges.
    Knowledge Acquisition: Human Factors Issues BIBA 351-355
      Deborah A. Mitta
    Knowledge acquisition is the process of extracting expertise from a domain expert. Expertise may be collected manually via a series of interviews held between the expert and a knowledge engineer of through sessions the expert holds with an automated knowledge acquisition tool. Several human factors issues become apparent: documenting mental models (where mental models are the expert's conceptualization of a problem), recording cognitive problem-solving strategies, and specifying an appropriate interface between the domain expert and the acquisition methodology. This paper provides a discussion of current manual/automated acquisition techniques, human factors issues associated with knowledge acquisition, and the ways in which several acquisition methodologies have confronted human factors issues.
    On the Use of a Primitive Formal Language and Ill-Defined Quantifiers in Knowledge Acquisition BIBA 356-360
      Gerhard Deffner; Reinhard Ahrens
    This paper describes a tool for knowledge acquisition and its empirical evaluation. The main characteristics are the use of a highly restricted language allowing for the expression of rules by means of cards and their combination. In order to assess the feasibility of the approach, subjects were trained in the use of a computer simulation that only gave them very general, unspecific, feedback about the internal workings of the system. It was their newly gained knowledge about how to control the system that was probed in a subsequent knowledge acquisition step. We observed substantial accuracy and also demonstrated its validity in a comparison against prior performance.
    The Mechanics of Representing Knowledge BIBA 361-365
      Dick B. Simmons; Terry D. Escamilla
    This paper describes mechanical knowledge representation schemes found in several popular expert system building tools (ESBTs). In order to realize the full potential of ESBTs, it must be possible to develop a knowledge base in one ESBT and transfer the knowledge into another. Porting a knowledge base across ESBTs requires a clear understanding of the mechanical knowledge representation properties supported by each tool. In the following discussion, properties considered include: canonicity; truth value; plausibility, certainty, and possibility (PCP); temporality; and procedural knowledge. The nature of each property is described along with comments on related knowledge base characteristics. A summary table appears below relating these properties to several popular ESBTs. Overlap found in many of the mechanical knowledge representation properties suggests that automatic knowledge base translation is feasible.
    Portability of an Expert System Knowledge Base BIBA 366-369
      Tony H. Haverda; Peter B. Reitmeyer; Newton C. Ellis
    To ensure the widest possible use of an expert system knowledge base, the knowledge base, in its final form, must be portable to a broad spectrum of user operating environments. Demonstrating that possibility was the objective of the research reported in this paper. Three cognitive issues, knowledge representation, inference mechanisms and problem solving procedures, as they pertain to portability were examined. Structuring the portability question in terms of these cognitive issues, two commercially available expert system shells, EXSYS and TI PC+, were used to ferret out problems and suggest practical solutions. Results determined that it is possible to formulate a consistent model of domain information in a knowledge base which is portable between shells.

    Computer Systems: Displays and Graphics

    Highlighting in Alphanumeric Displays: The Efficacy of Monochrome Methods BIBA 370-374
      Cheryl G. Spoto; A. J. G. Babu
    Highlighting is used to attract attention to displayed information. Prior work has called into question the efficacy reverse video as a highlighting method in alphanumeric displays. Brightness is highly recommended in guideline documents, but no empirical study of its efficacy in alphanumeric displays has been published. An experiment was conducted to investigate the efficacy of these methods in monochromatic, alphanumeric displays. Search time was significantly faster for reverse video than for high intensity highlighting. Reverse video may attract attention better than high intensity video. Heavy use of reverse video may aid in the systematic search of unhighlighted items. The results are analyzed in terms of a mathematical model.
    The Interactive Display Design Tool: An Application Program for Part-Task Simulation Development BIBA 375-379
      Christina M. O'Donnell; Mark W. Smith
    Traditionally, part-task simulation development has involved large amounts of time and effort. This was due to: 1) the inherent complexity of designing real-time software; 2) difficulty of converting dea/concept into specific software engineering requirements/specifications; 3) the need for extensive interconnected computer systems (both graphical and non-graphical). There are 3 activities involved in the creation of a part-task simulation: 1) the physical display format; 2) the definition of the input (Simulation Logic); 3) the definition of the response to the inputs (Display Logic). The Interactive Display Design Tool (IDDT) was a concerted effort to allow parts of the external interface to be created directly by interface designers, rather than software engineers. The original version of IDDT allowed the designer to interactively create and modify display formats. The current capability of IDDT allows interface designers to partially create and modify display and simulation logic. This paper discusses the specific methodology used within IDDT: display lists and look-up tables, and cites examples and capabilities of the tool. In conclusion, specific instances of significant savings in time and effort required for part-task simulation creation are given.
    Designing Screen Icons: Ranking and Matching Studies BIBA 380-384
      Peter R. Nolan
    Two studies from a screen icon testing program are reported. An appropriateness ranking study is a preliminary procedure that screens several candidate designs and results in a single image content for each icon. Subjects preferred the more concrete icons to the more abstract ones. Familiar image content was also preferred. The matching study determined how well the icons worked as a related set, and how likely it is that individual icons would be confused with each other. The icons for Clock, Drawing, and Voice score high on correct and low on incorrect. The symmetric and asymmetric confusions are identified and explained in terms of visual and conceptual similarity. There is a discussion of the methodology used.
    Differences in Performance and Preference for Object-Oriented vs. Bit-Mapped Graphics Interfaces BIBA 385-389
      Michael F. Mohageg
    This study used a standardized evaluation to compare two direct manipulation graphics interfaces: (1) object-oriented (vector) graphics and (2) bit-mapped graphics (object-oriented graphics interfaces are not to be confused with object-oriented programming or object-oriented data bases). Experienced and novice subjects performed objectively derived benchmark tasks appropriate for two-dimensional graphics packages. Both performance and preference data were collected. Task completion time, aborted attempts, learning effects, and errors constituted the performance measures. For the preference data, subjects completed questionnaires to rate the interfaces on both an absolute and a relative basis. Results indicate the superiority of the object-oriented graphics interface to the bit-mapped interface for most tasks, especially manipulation (e.g., scaling, moving, etc.) of graphics. The implications of these results for the use of direct manipulation graphics interfaces are discussed.

    Computer Systems: On-Line Information/Expert Systems

    The Content of Help Screens: Users versus Developers BIBA 390-393
      Richard S. Keister
    Following a training course where 15 entry operators received hands-on experience with a software application package and its help screens, questionnaires which included 34 help screen features to be rated as to their importance, was administered. Examining the ratings in terms of features which were included in the current help screens indicated that users were reasonably satisfied with the help screens except in two unimplemented areas: intelligent help and the ability to access all help screens from anywhere in the system. The same items were then rated by a sample of 15 software developers. Results showed that the two sets of ratings differed significantly. Examinations of individual items suggested that developers tended to place more emphasis on technical implementation of help systems, while users tended to be more concerned with items directly related to their jobs, such as the existence of step-by-step instructions and the ability to restore the entry screen.
    A Computer Aided Method for Assessing Accessibility of Information in Technical Documentation BIBA 394-398
      Lawrence Rowland; Evelyn Williams
    A methodology and a computer based program for testing documentation organization and location aids (tab-dividers, indices, tables of content and headings) was developed and used to aid the design and evaluation of documentation. The methodology and program allow computer analogs of documents to be tested before they were actually produced (based on detailed outlines).
       The documentation testing program presents the test subject a series of goal oriented user tasks. The subject then selects from a set of books and uses the existing location aids or paging to locate the heading that contains the information required to accomplish the task.
       The program automatically records use of the table of contents, tab-dividers, and index as well as the heading under which the subject believes the information will be found. The subject is allowed to make changes and additions to the tables of content, the index, and main body headings as the test progresses. The program runs in two modes. One mode provides feedback to the test subject on whether the final location is correct and tests how rapidly information can be found. Another model provides no feedback on the correctness of the locations and is used for developing models for the documentation based on user search paths and information content assumed to be under headings.
       The program has been used to evaluate documentation for a large computer operating system (HP-UX, a variant of UNIX) and the results show promise.
    Usability Analysis of Messages from a Security System BIBA 399-403
      William S. Mosteller; James Ballas
    Most software systems issue messages to reflect their progress in processing users' requests and to report error conditions. By instrumenting systems to collect these messages for later processing, a rich source of information about system and user behavior can be tapped. The work described herein is a study of system and user behavior related to messages, in an actual use setting. Our objective is assessing and improving the interaction with VMSECURE, a user directory management and security package for IBM's VM operating system. (VM is IBM's interactive system for mainframe computers. VMSECURE manages user resources and controls data access.)
       Pareto's principle to VMSECURE messages and error messages. A few different messages make up most of the traffic. Password prompting provides efficient, effective protection against unauthorized use of VMSECURE. Users of VMSECURE, when they receive an error messages, often re-enter the same, unsuccessful command again. Users of VMSECURE do not improve their error rates with experience, possible due to the low level of daily use they make of the product.
    An Expert "Critiquer" for Propulsion Gear Design: A Case Study in Intelligent Decision Support BIBA 404-407
      Ellen K. McKinley; Michael L. Mauldin; Emilie M. Roth
    This paper describes an "intelligent" designer's aid that was developed to support the design of marine propulsion gears. Key elements of the system include: conversion of gear design formulas from a procedural to a declarative form to facilitate inspection; a direct-manipulation interface; and encoding of "expert" design constraint knowledge. The case study demonstrates that delivering "expert knowledge" is often only a small element of an "intelligent" support system, and provides a concrete illustration of the importance of a cognitive task analysis in defining the elements of an effective support system. This design solution should have applicability to other engineering design tasks.

    Computer Systems: Computer Systems Potpourri

    A Pilot Study of Navigational Aids' Impact on the Usability of Hierarchical and Hypertext Databases BIBA 408-412
      Rachel E. Vail
    This pilot study investigated the relative effectiveness of various navigational aids for navigating through both hierarchical and hypertext database structures. Previous research has suggested that subjects perform more efficiently when using a spatial map of hierarchical structure. Similar data are not available for hypertext structures. The results of the present pilot study suggest that more in-depth investigation is required to judge the relative merits of the various aids for differing database structures.
    A Dynamic User-Adaptable Menu System: Linking it All Together BIBA 413-417
      John P. Chin
    Creation and traversal of links in a user adaptable menu was examined for syntagmatically and paradigmatically related targets. One group searched for paradigmatic related targets within the same intermediate category under different superordinate categories, while another searched for syntagmatic related targets belonging to different intermediate categories under the same superordinate. Users with syntagmatic targets created and traversed more superordinate category links, while users with paradigmatic targets traversed more intermediate category links. As predicted, more horizontal links at the same hierarchical level were created and traversed than diagonal links joining different levels. Overall, users tended to create links forming hierarchical networks.
    Problem Solving in Naive Users BIBA 418-422
      C. Michael Lewis; Wesley Jamison
    UnixTutor is a menu interface to UNIX being developed at the University of Pittsburgh as a training aid for new users. This paper compares mental models currently supported by the interface and those used by novices by examining subject logs from experiments. The paper concludes that UnixTutor provides good support for consistent aspects of the operating system but fails to support models novices need to deal with inconsistencies. Design enhancements are suggested for resolving this problem.
    Competitive Evaluation in Industry: Some Comments BIBA 423-425
      Jani Gabriel Byrne
    This paper examines competitive evaluations in industry. Competitive evaluations involve systematic comparisons between two or more products on similar (or equated) attributes. These attributes can be either usability criteria or usability characteristics. Three topics are discussed: applications of competitive evaluation information that could be useful to product development; industry pitfalls associated with conducting an evaluation; and timing of the evaluation in the product development process as it relates to the goals of the organization. The paper concludes with general suggestions concerning conducting competitive evaluations in industry.

    Consumer Products: Warnings!

    What is a Warning and When Will It Work? BIBA 426-430
      Thomas J. Ayres; Madeleine M. Gross; Christine T. Wood; Donald P. Horst; Roman R. Beyer; J. Neil Robinson
    The term warning is applied to a variety of stimuli. From a safety standpoint, the most appropriate definition of warning ties it to any information that has the potential to change behavior and prevent accidents. The results of an extensive literature review suggest that warnings are unlikely to be effective unless a series of conditions are met. The failure of many intended warnings, including most on-product warning labels, to reduce accidents reflects the difficulty of overcoming the problems inherent in their use.
    Effects of Warning Explicitness on Product Perceptions BIBA 431-435
      Kenneth R. Laughery; Julie A. Stanush
    A common assumption of manufacturers is that explicit warning labels will deter consumers from purchasing products. This study explored people's reactions to explicit and nonexplicit warning labels, where explicitness refers to how specifically the potential injury consequences were described. 108 subjects completed a 12-item questionnaire for each of nine familiar consumer products. The questions covered the severity of potential injury, product familiarity, product hazards and dangerousness, manufacturer's concerns, and potential purchasing decisions. Results suggest that products are perceived as more dangerous and related injuries as more severe when warnings are explicit. Also, with explicit warnings subjects report that they better understand the hazards, that they are being provided with all the necessary safety information, and that manufacturers are more concerned about safety. There was no clear indication that more explicit warnings either deter people from purchasing a product or increase the likelihood of a purchase.
    Pest-Control Products: Reading Warnings and Purchasing Intentions BIBA 436-440
      David C. Leonard; Kathryn A. Ponsi; N. Clayton Silver; Michael S. Wogalter
    This research is part of a large study examining people's perceptions of household pest-control products. Described in this report are the variables associated with peoples' willingness to read warnings on these products and the variables associated with likelihood to purchase. Two subject samples, comprised of 70 undergraduates and 20 adults, examined 22 pest-control products and responded to a questionnaire assessing perceptions of the products, the packaging, and the warnings. Results showed that product hazardousness, warning understandability, and warning attractiveness strongly related to subjects willingness to read the warnings. Unexpectedly, readability analyses indicated subjects would more likely read warnings with more sentences/statements and written at higher grade levels. A different set of variables was related to purchasing intentions. Subjects reported greater willingness to purchase products that were more familiar and which had more attractive packaging. Regression analyses were also performed to obtain models predictive of reading warnings and purchasing intentions. The results are discussed in terms of manufacturers' concerns of sales and consumer safety. The relative independence of subjects' purchasing intentions and the variables related to reading warnings suggests that manufacturers can place appropriate and effective warnings on pest-control products without the fear of reduced buying intentions.

    Consumer Products: Computer Hardware Design

    Reduced Keyboard Designs Using Disambiguation BIBA 441-444
      J. G. Kreifeldt; S. L. Levine; C. Iyengar
    There are a number of important applications where the accuracy of typed copy is less important than other criteria, such as the speed of entry, ease of learning, reduced keyboard size, provision of innovative keyboard designs and work methods, etc. Some of these applications include communication devices for the motor handicapped and rough drafting. The applications in question still provide single finger typing as opposed to multifinger entries for chord keyboards.
       One approach to keyboard design for such applications involves using a multicharacter set. Because there is more than one character on a key, the number of keys can be reduced to a point limited only by the required accuracy of the text produced which is itself limited by the ability of "disambiguation" algorithms to decode the ambiguous text strings. Reducing the number of keys increases test entry rates and reduces learning time.
       Experiments with keysets of 10, 12, 14, and 16 keys have produced keystroke rates of 3.3 to 1.7 characters per second and a 6% keying error while the disambiguation programs can produce an accuracy of 85 to 95%. Learning time in the experiments was about 9 to 12 minutes.
       The experiments demonstrate the feasibility of increasing text entry rates and freeing the keyboard from architectural constraints.
    Designing a Computer Pencil and Tablet for Handwriting BIBA 445-449
      Ellen Francik; Kenichi Akagi
    We designed a computer pencil and tablet for Freestyle, a multimedia communications system based on handwritten annotations. Although graphics pens and tablets are already in use for handprinted character recognition and CAD applications, designing a pen and tablet specifically for rapid, continuous handwriting required substantial changes. Design criteria came from a laboratory study in which evaluators performed various writing and drawing tasks with a working pen and tablet. Evaluators rated the working system, plus model pens and tablets that were variants on a proposed design. Field observations of working prototypes also contributed to the final product.
    Datahand: Design, Potential Performance, and Improvements in the Computer Keyboard and Mouse BIBA 450-454
      Leland W. Knight; Dale Retter
    This paper presents the design and preliminary evaluation of a new computer key and spatial entry system called Datahand. It is intended to improve human-to-computer data entry and control, as well as providing possible reduction of five major identifiable problems with conventional keyboards which subject operator to injury. The overall physical form of this product, its keys, and their organization, are unique in shape and function. Such a departure from traditional keyboards has presented an opportunity to consider new approaches to hand position, key design, spatial control and function. Preliminary empirical results from first users are covered in this paper.
    Product Evaluation of Three Competing Document Production Devices BIBA 455-459
      Patti L. Kelly Harrison; James R. Sayer; Harry L. Snyder
    Three competing document production devices were evaluated in terms of ease of learning and ease of use. Forty temporary office workers were hired to learn each device and then perform 16 identical exercises on each machine. After each exercise, the subjects were to rate the features assessed in that exercise along several seven-point rating scales anchored on either "Easy to Do" -- "Hard to Do" or "Easy to Remember" -- "Hard to Remember." After completing these exercises on each of the devices, the subjects were then asked to perform six additional exercises on the machines and to compare and rank them.
       Data consisted of subjective ratings from the exercises, the times required to complete each of the exercises, and the subjective rankings of the machines. Analyses of variance of the subjective ratings identified 78 out of 160 factors by which to distinguish the devices. These subjective factors were supported by an analysis of variance of the time data. Nonparametric analysis of variance of the subjective rankings of the devices identified an additional 23 out of 26 features by which the devices reliably differed.

    Consumer Products: Panel

    Challenges of Applying Human Factors to the Design of Commercial Products BIBA 460-464
      Wayne Fisher; Mark S. Hoffman; Paul Tynan; Robert M. Waters; Lothar R. Schroeder; Glen R. Gallaway
    Human Factors practitioners in engineering and manufacturing firms have significant challenges in applying and assuring the implementation of usability features in products designed for commercial markets. Educational programs, specialized training, and in general, the direction of the human factors profession which emphasize empirical methodologies and promotion of attitudes which reinforce the classical approach to applied research are often inappropriate for contributing to product developments.
       Root causes of the discrepancy between the use of formal Human Factors methodologies and the challenge of using these in product development are traceable to the origins of our profession. Frank discussion is needed within the profession to address this growing concern.
       The purpose of this panel is to provide insight into techniques used by practicing human factors professionals, foster discussions on how we can broaden the application of our discipline, and contribute more effectively to solving the challenges of integrating technology with users. Panelist represent a cross section of human factors specialists from product development firms. Each member promotes a different approach to practicing human factors; these approaches will help broaden the influence of our profession. A summary of these approaches is presented below.

    Consumer Products: Potpourri I

    Design of a Consumer Computer Terminal for Automated Access to Overnight Delivery Services BIBA 465-469
      Michael E. Maddox; James A. Turpin
    Consumer product design is seldom approached in a truly systematic framework, especially in applied settings. Although most designers know about systems design techniques, real design projects usually appear to be driven by severe scheduling constraints, cost limitations, strongly held opinions on the part of management and designers, or all of these characteristics. There has also historically been friction between human factors professionals and industrial designers. The result is that most consumer products have not undergone a truly systematic process of design and testing.
       This paper describes a case study in which a real product with potentially significant financial impact has been designed and is being tested using a systematic process. More significantly, this product represents a collaboration among company management, human factors professionals, and industrial designers. The overall design and testing process is described. Results from several tests, successively increasing the fidelity of the test items, are presented.
    Sentence Orientation and Semantic Processing Speed: Applicability to Label Design BIBA 470-473
      Tony J. Brown; Anthony Salvador; Brian E. O'Hearn; Jane E. Anderson
    Sentence orientation and category size were examined using a sentence verification task to determine whether the rotation of sentences would influence semantic processing. A total of 28 participants were asked to read sentences presented with five levels of rotation (-90, -45, 0, +45, +90) and two category sizes (small and large). A significant difference in the speed of sentence verification was found for sentence orientation. As the degree of rotation increased the time taken to process the sentences increased; this was especially true for vertically aligned sentences (oriented at +90 degrees). The category size variable did not yield a significant main effect. The findings of this study may have direct implications for the positioning of labels on consumer products with varying orientations.
    Riding Mower Control Placement Guideline Development BIBA 474-478
      Christopher C. Heasly; Randy M. Perse; Thomas B. Malone; Stephen A. Fleger
    Accident investigations and subsequent hazard analysis studies of power mower accidents conducted by the Consumer Product Safety Commission (CPSC), indicated that the current version of the American National Standard for Turf Care -- Equipment Power Lawn Mowers, Lawn and Garden Tractors, and Lawn Tractors -- Safety Specifications (ANSI/OPEI B71.1-l986) might benefit from review and/or revision. The analyses indicated control activation, placement and/or operation may have contributed to a number of the accidents reviewed. Accordingly, special emphasis was to be focused on review of Part 111: Ride-On Mowers, Lawn Tractors, and Lawn and Garden Tractors, paragraph 13., Controls.
       This paper describes the approach utilized in development of the inputs to update ANSI/OPEI B71.1-1086. Additionally, the paper describes a brief overview of the voluntary standard review/acceptance process.
    Developing a Voluntary Safety Standard for Step Stools BIBA 479-482
      Beth A. Loring
    American Institutes for Research (AIR) assisted the Consumer Product Safety Commission (CPSC) to identify the human factors issues that should be addressed in a forthcoming voluntary safety standard for step stools. According to CPSC data, older people, children, and women of all ages are over-represented in step stool accidents. We studied the accident scenarios, recommended requirements for step stools, and evaluated the completeness of a draft of the standard with respect to user interaction.

    Consumer Products: Potpourri II

    Knurls on Pop Bottle Lids BIBA 483-485
      Stephan Konz; H. Ravishankar
    Do knurls improve torque capability? A "pop-bottle" size lid (28 mm diameter, 15 mm high) was varied with six designs: 1) a smooth lid, 2) a lid with 13 knurls/cm, 3) a lid with 7.9 knurls/cm, 4) a lid with 3.9 knurls/cm, 5) a lid with 3.9 knurls/cm but for only 4 mm of height, and 6) a lid with 2 protrusions ("radiator type"). The 18 subjects rotated each lid. Using the smooth lid torque of 1.49 Nm as 100%, the lid with 7.9 knurls/cm had 170%, the radiator type had 164%, the 13 knurls/cm had 163%, the 3.9 knurls/cm had 141%, and the 3.9 knurls/cm for only 4 mm had 110%.
    Optimal Position of D-Handles on Snow Shovels BIBA 486-489
      M. Ali Montazer; Roberto G. Ruiz; Matthew S. Sanders
    Handles and handle designs have been the subject of numerous studies over many years. There are a number of studies concerned with parameters such as the size, shape, and length of handles as they affect human performance and work efficiency. This study is concerned with D-handles on snow shovels. A simulated snow shoveling experiment with 13 subjects was conducted to determine the optimal position of D-handles on snow shovels. The shovels used were identical with respect to the length and size of their handles as well as blade shape. However, they differed in the angular position of the D-handle with respect to the shovel blade. Subjective rates of perceived exertion and body parts discomfort were collected. Analysis of the data showed significant subject differences but insignificant shovel type differences. The graphical examination of the data reveals that D-handles positioned in the 0 to 30 degree range scored the lowest rates of overall exertion and body parts discomfort.
    Human Factors Design Guidelines for the Disabled BIBA 490-492
      John T. Ward
    In an effort to develop human factors guidelines for designing consumer products for the disabled a series of interviews and surveys were conducted in the homes of noninstitutionalized disabled people. Thc study covered a variety of disabilities, and where possible, individuals with several different levels of a given disability were included. A detailed set of recommendations of specific controls for use on products to be used by disabled people was found to be impractical because interfaces which are desirable to one disabled person are often a bad choice for another. The greatest problem for most disabled consumers is the variety of controls often found on a product. If one key control is inoperable by a person, the product may be unusable for that person. A preferred method for designing for the disabled is to use less variety in the selection of controls on each product. By reducing the within product variability along certain key design dimensions an individual capable of using some of the controls is more likely to be able to use them all.

    Educators' Professional: Human Factors Education: Issues and Answers

    Now the First Class has Graduated: Some Thoughts on Beginning and Maintaining a Human Factors Program BIBA 493-496
      Thomas A. Dingus
    The objective of this paper is to describe the experience of beginning and maintaining a human factors graduate program, and to provide some thoughts on and insights into the program's future. The curriculum developed for the program is described, as well as impressions about student requirements and success, coursework, the job market, industry support and the potential for program expansion.
    Human Factors as Design: An Attempt to Bridge the Gap between Basic and Applied Research BIBA 497-499
      Neville Moray
    This paper describes a course in the human factors of the design of complex systems. The course content, methods, and source materials were chosen to emphasize the possibility of using "basic" research in the applied problem of designing complex human-machine systems. Students were required to handle interdisciplinary knowledge and work with engineers on designing a process control plant.
       Three important principles are proposed to enable basic research to be applied to design problems. These are the Principle of Boundary Conditions which allows false theories to be useful: the Principle of Limiting Values, which allows exact quantities collected in context free research to be used in context dependent design: and the Principle of Importance in statistics, which states that significant results which have small magnitudes should be ignored in design.
       The paper will describe the experience of centering human factors training on design rather than knowledge acquisition.
    Educating Engineering Psychologists: Are We "Going Around in Academic Circles"? BIBA 500-504
      Dennis B. Beringer; David W. Martin
    In 1972 Hunt, Howell, and Roscoe examined and compared the goals of various educational programs for engineering psychologists. Two years later Martin considered "What is wrong with human factors students?" The present treatise is an attempt to discover whether we are operating in a closed universe and have in fact come 'round to our starting point or have progressed in our attempts to equip students for gainful employment. Comparisons are drawn between the state of the educational process then and its present condition, including data on basic skills (NAEP, Spring 1989) and higher-level thinking abilities (anecdotal and empirical) or lack thereof. Contemporary problems are outlined and sources of these difficulties are identified where possible. Problem areas include deficiencies in student preparation, academic and industrial short-term corporate memory, supply-demand communication, economic forces, and the issue of certification (individuals and programs). The authors conclude by examining where current trends may be taking us.

    Educators' Professional: Demonstration

    Use of Microcomputers to Teach Human-Factors Engineering: New Directions BIBA 505-506
      Andrew G. Stricker; Paul M. Grunzke; Schuyler Huck; Gary Macomber
    Assorted software used to assess and instruct students is presented. Both in-house and commercially available software were selected on the basis of their innovative approaches to the microcomputer learning experience. Also, software samples are presented which illustrate the teaching of cognitive-behavioral skills in addition to the domain knowledge.

    Educators' Professional: Educating from A Group Perspective: What, Why, and How

    Educating from a Group Perspective: What, Why and How BIBA 507-511
      David B. Porter
    "What a person thinks on his own, without being stimulated by the thoughts of others, is, even in the best case, rather paultry and monotonous" -- Albert Einstein (in Winokur, 1984, p. 106). Einstein also make his disdain for traditional approaches to education clear: "The crippling of individuals is the worst evil of our educational system. An exaggerated competitive attitude is inculcated into the student, who is trained to worship aquisitive success..." (in Seldes, 1983, p. 223). Current developments in cognitive and social psychology support Einstein's candid observations. These developments suggest our perspective on education should be broadened to include interpersonal, group and organizational factors.

    Environmental Design: Occupied Indoor Space

    Computer Aided Design of the Thermal Environment BIBA 512-516
      Kenneth C. Parsons
    The use in design, of knowledge and understanding of human thermal comfort, heat stress and cold stress, is often complex and time consuming. A computer based system (IBM-PC) was developed to allow human factors practitioners to assess and manipulate knowledge, data and simulations of human response to thermal environments, thus allowing computer aided design. A description of the system, its design and development and examples of its use are provided. The role of such systems in design and assessment should be considered by human factors practitioners.
    An Evaluation of Floor Surfaces BIBA 517-520
      Malgorzata Rys; Stephan Konz
    Three floor surfaces (concrete, a San-EZE-7/8" thick resilient rubber mat, and a Traction Mat-3/8" rubber mat with raised knob design) were evaluated based on foot dimensions, lower leg and foot temperature and body comfort. Nine college students (2 females) stood for one hour on each of the floor types performing two types of visual inspection: inspecting pennies for a particular year, and inspecting pennies for several years at a time. There was a significant difference in body comfort between floor surfaces. Both mats were better than concrete (although not always statistically significantly so). The Traction mat was better for upper, mid and lower back comfort; the San-EZE mat was better for lower leg, ankle, hindfoot and forefoot. The temperature of the calf and instep was significantly higher for both mats than for concrete.
    Lighting the Computerized Office: A Comparative Study of Parabolic and Lensed-Indirect Office Lighting Systems BIBA 521-525
      Alan Hedge; William Sims; Frank Becker
    A comparative field survey of the effects of two alternative lighting systems, a parabolic downlighting system and a ceiling suspended, lensed-indirect lighting system, on computer workers in a virtually windowless office was conducted. A questionnaire, collecting data on work content, perception of ambient environmental conditions including office lighting, work-related health symptoms, job stress and job satisfaction, and self-reported productivity was completed by 96 workers. Results show that the lensed-indirect lighting system was rated significantly more favorably on several subjective lighting quality scales, and significantly more appropriate for computer based work. Workers reported less problems with glare on their computer screen and with work being hindered, fewer eye problems (tired eyes, trouble focusing eyes), better productivity, and significantly higher satisfaction for the lensed-indirect system compared with parabolic lighting.

    Environmental Design: Space and Transportation

    A Cross-Cultural Survey of Personal Preferences in Design and Operation of a Lunar Base BIBA 526-530
      James A. Wise; Kristiina McConville
    This paper reports the results conducted at the International Space University during its inaugural summer of 1988. The survey concerned personal preferences in design and operations options for a hypothetical lunar base which was the focus project for the class. The results showed potential cultural differences in desires for dress codes, alcohol usage, calendar observances, and other design and operations procedures. These differences suggest that in the planning of future space bases, significant attention should be directed towards the special needs of culturally diverse crews to ensure that optimal habitability, job performance, and crew relations goals are realized.
    Crew Quarters for Space Station BIBA 531-535
      F. E. Mount
    The only long-term United States manned space mission completed has been Skylab, which has similarities as well as differences to the proposed Space Station. With the exception of Skylab missions, there has been a dearth of experience on which to base the design of the individual Space Station Freedom crew quarters. Shuttle missions commonly do not have sleep compartments, only "sleeping arrangements". There are provisions made for each crewmember to have a sleep restraint and a sleep liner, which are attached to a bulkhead or a locker. When the Shuttle flights began to have more than one working shift, crew quarters became necessary due to noise and other disturbances caused by crew task-related activities. Shuttle missions that have planned work shifts have incorporated sleep compartments. To assist in gaining more information and insight for the design of the crew quarters for the Space Station Freedom, a survey was given to current crewmembers with flight experience. The results from this survey were compiled and integrated with information from the literature covering space experience, privacy, and human factors issues.
    Human Factors Design Considerations for Military Trains BIBA 536-540
      Daniel McCrobie
    This report describes a research project to develop and verify habitability and human factors design criteria as applied to the design of a train Verification of these design criteria was done via an iterative, usability test program with actual user personnel. The results of the first set of studies suggest that this test process improved the design of the system. The methods and results sections of this report contain specific design solutions and general comments that were developed during the test process.
    An Evaluation of the Signposting System in a Large Subway Station BIBA 541-545
      Ruth J. Arnegard; Monty L. Hammontree; Melinda J. Montgomery; Gwen L. Pearson; Harm J. G. Zwaga
    The purpose of this study was to objectively evaluate the signposting system within the Metro Center subway station of the WMATA (Washington Metro Area Transit Authority). The approach taken was: first, to estimate the prevalence of passenger behaviors indicative of deficiencies in wayfinding; second, to evaluate the adequacy of the signposting within various decision areas of the station; and finally, to evaluate the individual components of the signage system.
       The first objective was addressed by observing 507 passengers selected via a pseudo-random sampling technique. From this sample an overview of traffic patterns was developed and it was determined that roughly 7% of these passengers followed a route that did not comply with the directions provided by the stations sign posting system. It was further found that an additional 2% asked for direction. These figures were combined with data provided by the WMATA to project that 6,000 to 7,000 of the passengers disembarking a train within Metro Center will evidence some form of inefficient wayfinding behavior each day. To address the second question, portions of the randomly sampled data were combined with data gathered from a selectively sampled group of passengers operationally defined as needing wayfinding assistance (n = 359). This data was analyzed to determine the relative difficulty that information needy passengers had in finding their way through the various areas of the station. The final objective was addressed by comparing individual components of the signage system to current human factors guidelines.

    Environmental Design: Panel

    Technological Support for Group Work: Merits and Limitations of Computer-Supported Cooperative Work BIBA 546-549
      Paul Cornell; Robert Luchetti; Lisbeth A. Mack; Gary M. Olson; Phil Stone; Eric Sundstrom
    There is a strong trend in American business towards the use of teams and groups. New products are being introduced to support this emerging work style. A new field of study, commonly known as computer-supported cooperative work (CSCW), has emerged which focuses on provided electronic support for group activities. One particularly active area is the electronic meeting room, where computers support teams meeting in the same time and place. These facilities typically provide meeting participants with a terminal, keyboard and mouse and link them to a large public display. Existing rooms, some of which have been in operation for several years, accommodate anywhere from two to 48 people. To date, most of the research attention has been devoted to developing the hardware and software for these facilities. This focus is shifting and research is now underway addressing the impact of CSCW on group performance and viability. This panel has three objectives: to discuss the merits and limitations of CSCW in the context of organizational, environmental and technological factors, to predict its potential impact now and in the future, and to discuss a research agenda. The opinions of the panelists are mixed. Some feel CSCW has already proven its value, even though the technology is in its infancy and the data are anecdotal -- its worth will only improve with time. Others are concerned about trying to design and provide tools for a process that is not well defined or measured -- other more important issues need to be addressed first. Consensus exists on the need for more empirical research, but the nature and priorities of that research agenda is a subject of debate.

    Forensics Professional: Forensics Forum: Research for Litigation

    Risk Perception and the Use of Warnings BIBA 550-554
      S. David Leonard; G. William, IV Hill; Edward W. Karnes
    The purpose of the studies was to develop information about how the general public perceives the degree of danger represented by signal words in warnings. Although many organizations have guidelines for the determination of what signal words are to be used with specific hazards, these are usually unknown to the public. For 15 items that have been rated for the seriousness of risk, 288 subjects were asked to indicate which signal word they would use to inform others of the hazard. Signal words that can had been found to rate high in seriousness by Leonard, Karnes, and Schneider (1988) tended to be used more with items rated as high risks. Differences were found among age groups with older subjects using signal words that carried more serious connotations. The possible warnings that might be used were discussed.
    Broadening the Range of Signal Words BIBA 555-559
      N. Clayton Silver; Michael S. Wogalter
    Most guidelines on warning design recommend using an appropriate signal word that connotes the degree of hazard involved. Usually three levels of signal words, DANGER, WARNING, and CAUTION are suggested for warnings that convey high to low degrees of hazard. The purposes of the present research were threefold. The first goal was to examine whether these terms differed in implied hazard level. The second goal was to determine whether an additional group of five words recommended in guidelines or used in previous research differed in connoted hazard level. The third goal was to explore the possibility of increasing the number and range of words that connote different levels of hazard. Subjects rated a list of 84 potential signal words on six questions assessing strength, severity of implied injury, likelihood of implied injury, attention-gettingness, carefulness, and understandability. The results indicated that DANGER connoted greater strength (arousal) than WARNING and CAUTION, but the results failed to show a difference between WARNING and CAUTION. Among other words tested, DEADLY was seen as having strongest arousal connotation, and NOTE the least. From the long list of 84 terms, a "short" list of 20 signal words was developed based on understandability, low variability, shortness of word, and frequency of use. It is suggested that an expanded list of signal words might alleviate potential problems of habituation from overuse of the currently recommended terms.
    Public Knowledge and Understanding of Overhead Electrical Power Lines: A Second Look BIBA 560-564
      Kent P. Vaubel; Kimberly A. Donner; Susan L. Parker; Lila F. Laux; Kenneth R. Laughery
    Public knowledge and understanding of the hazards associated with overhead power lines were examined in the greater Houston, Texas area. A 1988 public opinion survey was conducted as a follow-up to a similar 1982 survey which found the public to be ill-informed about power lines. Partly as a result of these 1982 findings, the Houston Lighting and Power Company initiated a public education program aimed at increasing its customers' power line hazard knowledge The program consisted of TV and radio broadcasts, newspaper advertisements, and bill inserts (stuffers). The purpose of the present research was to determine the effects of this educational program. 306 respondents were interviewed by telephone over a two month period. Results of the present survey were similar to those found in 1982 indicating virtually no change occurred in power line hazard knowledge as a result of the safety education program. Specifically, people did not know that power lines are uninsulated, nor did they have an understanding of the amount of electricity transmitted by these lines.

    General Sessions: Panel

    Human Factors Research with Special Populations will Further Advance the Theory and Practice of the Human Factors Discipline BIBA 565-566
      Douglas Griffith; Daryle Jean Gardner-Bonneau; Alistair D. N. Edwards; Jerome I. Elkind; Robert C. Williges
    The advent of Public Law 99-506 (ensuring access to electronic office equipment by individuals with disabilities) is causing an increasing number of human factors professionals to examine what the field of human factors has to offer the design of equipment for special populations. Historically the involvement of human factors people in these efforts has been small. So, a reasonable proposition to examine is the title for the panel discussion: Human factors research with special populations will advance the theory and practice of the human factors discipline. One possible view of this proposition is negative; namely, that the involvement of human factors professionals with special populations will benefit neither the discipline nor the population. If a positive view is taken, then there are both weak and strong forms of the proposition. The weak form argues that there is a need to expand human factors methodologies to handicapped populations because there are significant numbers of people who would benefit and that the human factors data base would be significantly expanded. The strong form maintains that the basic theory and practice of human factors will be advanced to the ultimate benefit of the nonhandicapped population.

    General Sessions: The Work of the NAS/NRC Committee on Human Factors

    The Work of the NAS/NRC Committee on Human Factors BIBA 567
      Douglas H. Harris
    Since 1980, the National Academy of Sciences (NAS) has had a standing committee on human factors as part of its operating agency, the National Research Council (NRC). The Committee on Human Factors, like other NRC committees, serves as an independent advisor to the federal government -- identifying critical theoretical and methodological issues, defining the state of knowledge with regard to these issues, and determining research needs and their priorities. In this capacity, the Committee has the opportunity to provide new perspectives on human factors and to guide the direction and support of future human factors research and development. The purpose of this symposium is to provide an overview of the origins and purposes of the Committee on Human Factors, and to present examples of some of its recent work.
    The National Research Council Committee on Human Factors BIBA 568-570
      Harold P. Van Cott
    The Committee on Human Factors, a standing committee of the National Academy of Sciences/National Research Council (NAS/NRC), advises its sustaining sponsors and other requesting organizations on issues involved in the design of socio-technical systems and on the research and methods needed to help enhance their operability and safety. This paper describes the origins, purposes, operations and program of the committee and emphasizes the special attributes of this and other NAS/NRC committees.
    Ergonomic Models of the Human at Work BIBA 571-575
      Karl H. E. Kroemer
    A COHF/NRC Workshop assessed the status of anthropometric, biomechanical, and human-machine interface models. Their development into an integrated model, or compatible modules, appears feasible and needed.
    Human Factors Research and Nuclear Safety BIBA 576-578
      Neville Moray
    This study was undertaken at the request of the United States Nuclear Regulatory Commission to advise them as to the necessity for a new program of research into human factors of nuclear safety following the decision to terminate research in that area in 1985. The study showed in a particularly striking way how necessary a systems approach is to the application of human factors to complex systems. It is not possible to foresee the impact of human factors on complex human-machine systems without extending the definition of human factors to include disciplines such as social and organizational psychology, management sciences, and sociology. Following the presentation of the report to the Nuclear Regulatory Commission human factors research has again begun, and the report seems to have had a significant impact on the direction and scale of work supported by NRC in this area.

    General Sessions: Coping with Automation: Testing the Limits of Human Performance

    Teleoperator Interfaces for Remote Control Centers/Test Beds BIBA 579-583
      H. McIlvaine Parsons
    A survey has been conducted to create a data base of design aspects of human-machine interfaces in remote control centers and test beds for teleoperated vehicles, which are a proliferating technology challenging human factors engineers and scientists. Such vehicles, some of which carry manipulators as well as sensors, can be viewed as a subset of robotics.
    End-Effector Velocity and Input Frequency Effects on Teleoperator Performance BIBA 584-588
      John V. Draper; Stephen Handel
    End-effector velocity defines two types of servomanipulators: operator-paced systems and machine-paced systems. Input frequency limits below human bandwidth may also cause machine-pacing. Two experiments varied end-effector velocity limits (1.01 meters per second, 36.4 centimeters per second, and 76.2 centimeters per second) and input frequency limits (0.16 Hz, 0.32 Hz, 0.61 Hz, and 1.27 Hz). Multivariate analyses of variance found statistically significant input frequency limit effects in one experiment, and significant input frequency and velocity limit effects in the second experiment. Machine-pacing caused by input frequency occurred in the range hypothesized (between 0.32 Hz and 0.64 Hz). The critical velocity limit appeared to be lower than expected (between 76.2 cm and 86.4 cm per second). These results are valuable for future teleoperator designs.
    Modifying Fault Diagnosis Strategies BIBA 589-592
      Marc A. Sullivan; George J. Boggs; Kathryn M. Dobroth
    This study investigated the ability of trained diagnosticians to alter their strategies in situations where either time or testing must be kept to a minimum. Four subjects, extensively trained in previous experiments on fault diagnosis, participated in time bonus and testing efficiency bonus conditions. They isolated faults in networks of 25 nodes connected by links. In the time bonus condition, subjects were rewarded for the number of problems completed within a time limit. In the test bonus condition, subjects were rewarded for minimizing the number of tests used to diagnose a fault. Total diagnosis time was lower in the time bonus condition, and the number of tests was lower in the test bonus condition. In the time bonus condition, subjects tended to make initial tests more rapidly than they did in the test bonus condition, and the location of initial tests was relatively "shallow" in the network. The between-subject variability in diagnosis time was larger in the test bonus condition than in the time bonus condition. There was no significant difference for between-subject variability in testing efficiency. These results suggest two important conclusions regarding fault diagnosis. First, trained diagnosticians can rapidly adapt their diagnosis strategies to changes in their problem domain. Second, explicit payoffs can, in some cases, reduce the individual differences in fault diagnosis performance. This appears to be partly due to strategies becoming more similar under explicit payoffs. It is suggested that in future studies the use of explicit payoffs should be considered.

    General Sessions: Panel

    Contracting for User Interface Design in Military Systems BIBA 593
      Jane N. Mosier; Mildred D. Jarvis; Donald L. Monk; Larry H. O'Brien; Robert Simon
    Many of the systems the Government acquires contain a large amount of software. Some are limited almost exclusively to off-the-shelf computer hardware, and software that is developed by a contractor. But human factors in military systems is regulated by documented standards and procedures that were developed before software gained an important role in military systems, and so do not deal with issues specific to user interface design. The purpose of this panel is to discuss user interface design issues and to propose changes to the acquisition process to improve user interface design for military systems.

    General Sessions: Innovative Methods and Techniques in Applied Human Factors

    Methods for Combining Human Factors Research Results: Meta-Analysis BIBA 594-596
      Nancy S. Anderson
    Meta-analysis has been used frequently for combining research results across a series of studies. A brief review of those content areas of the social and behavioral sciences using meta-analysis is presented and reasons are suggested why these techniques are not presently used by human factors specialists.
    MIPS and BIPS are Megaflops: Limits of Unidimensional Assessments BIBA 597-601
      William W. Banks; Michael Pihlman
    We believe that a failure to incorporate human performance measures into system test protocols will result in imprecise and incomplete data when an attempting to estimate field test performance from a total systems perspective. Traditional methods of evaluating local area network performance generally refer to the network's throughput, time delays, data rate (BIPS), or media access protocol efficiency. These measures are quite acceptable when determining point-to-point benchmark network performance but do not take into account the more global man-machine performance issues associated with people using network systems to perform tasks and execute functions concurrently within a "total systems" context. This paper experimentally compares differences in human productivity/efficiency while using: 1) an existing data gathering system consisting of several geographically distributed, unconnected, and disparate mainframes; and 2) a prototype Intelligent Gateway (Local Area Network) connecting mainframes and offering the user less complexity in procedure execution and an easy to use interface. Tests were conducted with volunteer users in a repeated measures experimental design. Each test subject was randomly assigned to each of two conditions and required to execute routine tasks with each of two systems. ANOVA results revealed significant differences in task completion times and human error rates between the two systems. An increase in human productivity/efficiency was observed using the gateway LAN. We propose to extend the traditional computer performance measurement (monitoring) boundaries, which now encompass only the network hardware, to include an overall "input-to-output" local area network performance measure, combining both measures of user productivity and network performance. A discussion of trade-offs between unidimensional assessment methods using large sample sizes and multiple methods with small sample sizes is also presented. We further believe that without the addition of specific behavioral measures, MIPS and BIPS are truly Megaflops.
    Dollars and Sense: Using Effect Size Estimates to Make Design Decisions BIBA 602-605
      Jon Weimer; Arlie Hart
    An alternative to using large numbers of test participants is offered for HF professionals with limited budgets. This alternative justifies design decisions using effect size estimates which have been calculated from published data germane to the design of the particular system. The calculations for effect size estimation are given in simple algebra, using only the information available from published ANOVA summary tables.
    Integrated Research Paradigm for Complex Experimentation BIBA 606-610
      Robert C. Williges; Beverly H. Williges
    Most human factors design problems involve large data spaces with so many factors that a single experiment investigating all of these factors simultaneously is unreasonable. The design of a computer-based telephone inquiry system is presented as an example interface which required consideration of over 100 independent variables which could affect end-user performance. An integrated research paradigm involving the three major steps of selecting, describing, and optimizing these independent variables is presented. Specific methods and design implications are described for each of these steps. This overall strategy for sequential experimentation is discussed in terms of its usefulness in human factors design applications.

    General Sessions: Automobiles and Highways

    Commuter Behavior and Decision Making: Designing Motorist Information Systems BIBA 611-614
      Woodrow Barfield; Mark Haselkorn; Jan Spyridakis; Loveday Conquest
    This research reports on the results of a large sample survey designed to investigate the response of the survey was to investigate the impact of traffic information on commuter's route choices, mode choices, and departure times, and to determine whether motorists could be categorized according to their specific information needs. The surveyed population consisted of 9,652 home-to-work Interstate five (I-5) commuters, of which 3,892 (40%) returned usable surveys for analysis. Using the cluster analysis statistical technique, four commuter subgroups were shown to exist with respect to their willingness to respond to the delivery of real-time traffic information. These groups were: (1) route changers, those willing to change routes on or before entering I-5 (20.6%), (2) non-changers, those unwilling to change time, route, or mode (23.4%), (3) time and route changers (40.1%), and (4) pre-trip changers, those willing to change time, mode, or route before leaving the house (15.9%). The response of these commuter groups with respect to several variables and some applications of this data to the creation of motorist information systems are discussed.
    A Human Factors Evaluation of Freeway Guide Sign Lighting Systems BIBA 615-619
      Jonathan E. Upchurch; Jeffrey T. Bordin
    The objective of the study was to identify a lighting system for freeway guide signs which is more economical and which adequately satisfies motorist's needs in terms of legibility, illumination, color rendition, and other factors. Through the use of technical data and specification review, photometric tests, and computer analyses, ten lighting systems were selected for field testing (10-14 months). Luminance levels, power consumption, maintenance requirements, and lamp life were noted. A human factors study determined legibility distance and rated viewing comfort, lighting uniformity, and color rendition. Senior citizens and young adults were used to detect possible age-related differences. None were noted other than seniors placed more importance on color rendition. It was determined that the differences between the best human factors performing lighting systems and the best regarding economics was only marginal concerning human factors. The most economical system was thus recommended.
    Analyses of Automobile Interiors Using a Semantic Differential Method BIBA 620-624
      Youji Shimizu; Takayuki Yanagishima; Mitsuo Nagamachi; Tomio Jindo
    It is important to design and engineer cars with greater emphasis on human sensibilities in order to create an attractive, habitable car interior. In this research, the impressions people receive from a car interior were evaluated using the semantic differential method. The results made clear the evaluation structure of interior habitability and the relationship between subjective impressions and design/aesthetic elements. The knowledge gained through this research provided the foundations for establishing a simulation procedure for evaluating car interior impressions.
    The Effects of 48 Hours Total Sleep Deprivation on Human Physiology, Mood, and Memory BIBA 625-629
      Mary L. Rankin; Georgia Latham; Robert D. Peters; David M. Penetar
    Previous research regarding the effects of sleep deprivation (SD) on human physiology and mood has yielded conflicting results. These findings may in part be due to the use of small sample sizes and the failure to separate out the pure effects of SD from those of circadian rhythms during data analysis. One purpose of this study was to clearly identify the effects of 48 hours of SD on blood pressure, temperature, heart rate, and mood by overcoming the limitations of previous research. A second purpose was to evaluate the effects of SD on recognition memory. A repeated measures design was employed to collect physiological, mood, and memory data over a 48 hour period. While strong circadian rhythms were observed for most of the physiological and mood variables, recognition memory was unaffected by 48 hours of SD.

    General Sessions: Panel

    The Practical Aspects of a Usability Lab BIBA 630-631
      Hardy Mason; Deborah Mrazek; Kathy Uyeda; Robert Virzi; Ricky Savage
    This panel will explore the practical issues behind the scenes of a Usability Lab. The following topics will be discussed: how the labs are designed and built, including types of video equipment; what situations produce the need for a lab; the history of some of the labs; lessons learned in running a lab; and how Usability Labs will be utilized in the future.
       The panelists will be from different industries, testing different types of ideas, theories and products. Some of the Labs represented are several years old and some are just under construction.
       Usability lab testing is no longer restricted to academia and larger corporations. It is useful for many of us.

    Industrial Ergonomics: Strength Assessment

    Isokinetic Strengths and Working Posture BIBA 632-636
      Anil Mital; Ashraf M. Genaidy
    This paper presents isokinetic (dynamic) pull-up strength profiles of males and females, engaged in infrequent force exertion, in fifteen different working postures ranging from kneeling to standing. Maximum pull-up force was exerted with two hands in the stooped posture. Least force was exerted with the preferred hand at reach distance, in the sagittal plane (arm fully extended), in the sitting posture. As expected, large differences existed in the force exertion capability of males and females.
    Isometric Pushing, Pulling, and Lifting Strengths in Three Postures BIBA 637-640
      Sean Gallagher
    Nine underground coal miners (Mean age = 36.9 yrs + 6.3 SD; height = 174.5 cm + 7.4 SD; weight = 87.8 kg + 12.5 SD) participated in a Bureau of Mines study examining the effects of posture on isometric strength. Five tests of static strength (i.e. maximum push, maximum pull, maximum lift with elbows flexed at 90 degrees, maximum lift with lifting handle 45.7 cm [18 inches] above floor, and maximum push up with handle at eye height) were performed in three postures: standing, kneeling on one knee, and kneeling on two knees. Results indicated that neither test of lifting strength was affected by posture (p > 0.05). However, maximum pulling strength was significantly greater when kneeling on one knee (p < 0.001) than when standing or kneeling on both knees. Also, maximum pushing strength was greater when kneeling on both knees than when standing (p > 0.05). The test of maximum push up was not affected by posture (p > 0.05), and the force generated in the three postures for this test were highly correlated (r = .94). Results of these strength tests may be useful when recommending appropriate postures to assume when performing specific underground materials-handling tasks.
    Maximum Forces in Simulated Meat Cutting Tasks BIBA 641-645
      M. J. Jorgensen; M. W. Riley; D. J. Cochran; R. R. Bishu
    This study attempts to evaluate maximum force capabilities of subjects performing fourteen different simulated meat cutting tasks. The different tasks represent different cutting positions related to the orientation in which the meat is presented and the types of trimming cuts. The experiment was conducted to measure maximum force capability against two constant velocities produced by a Cybex II dynamometer through the range of motion for the simulated meat cutting tasks. The results of this experiment produced a basis for selecting cutting orientations based on force capability for cutting in these fourteen motions. Based on this, the desirability of different cutting orientations for meat trimming jobs has been established.
    Effects of Fatigue on Muscle Groups under Dynamic Exertions BIBA 646-650
      Gary A. Mirka; Carolyn M. Sommerich; William S. Marras
    The present study was a quantitative investigation into the substitution patterns and other fatigue-related characteristics of the muscles of the upper leg during dynamic activity. Subjects performed fatigue-inducing leg extensions under varied force and velocity conditions. Electromyographic (EMG) data revealed subject dependent muscle substitution patterns that varied as a function of force/velocity combinations. The results also indicate an interaction between leg angle dependent variables and fatigue. Explanations for these effects are discussed.

    Industrial Ergonomics: Manual Materials Handling

    A Psychophysical Study of Two-Person Manual Material Handling Tasks BIBA 651-653
      Steven L. Johnson; David M. Lewis
    Over the past ten years, there has been extensive work performed on the development of guidelines for manual material handling tasks both within individual companies and within governmental agencies. However, these guidelines address only individual, one-person lifting tasks. In both manufacturing and service industries, there are many team lifting tasks, such as furniture moving and at loading docks. This paper presents the results of a study that used psychophysical methods to investigate lifting tasks that require two workers. In addition to simple lifting tasks, the study also compared one and two-person carrying tasks. The results of the study indicate that subjects' judgments of their lifting capability are significantly greater for the two-person lifts than for the individual lifts. The same relationship was observed for the carrying tasks. These results and conclusions are important to consider when it is necessary to extrapolate from the conditions used in the development of manual material handling guidelines to other situations such as team lift carrying tasks.
    Effects of Measured versus Proposed Horizontal Distance on the NIOSH Action Limit and Maximum Permissible Limit for Manual Materials Handling BIBA 654-656
      Arun Garg
    The objective of this research was to compare action limits and maximum permissible limits based on measured horizontal distances with those based on the rule of thumb proposed in the NIOSH Guide. Thirteen male subjects were required to lift three different boxes (25, 38 and 51 cm wide), at four different frequencies (0.2, 3, 6 and 9 lifts min-1) and at two heights (floor level to bench height (0.8 m) and bench height to 1.5 m). Each lift was performed for one hour and horizontal distances for all thirteen subjects were measured at the origin of lift. Action limits and maximum permissible limits were computed for all lifting tasks using the measured and the proposed horizontal distances. The actual measured horizontal distances were much greater than those based on half the box width plus 15 cm. The action and the maximum permissible limits based on measured horizontal distances were significantly lower than those based on H = W/2 + 15 cm. For the floor to 0.8 m lifts, the AL and MPL based on measured horizontal distances were 74% (range = 67% to 80%) of those based on H = 15 + W/2. The corresponding ratio for the 0.8 m to 1.5 m lifts was 62% (range = 56% to 66%).
    Weight Discriminability and Subjective Assessment of Load Heaviness: A Pilot Study BIBA 657-661
      Waldemar Karwowski; Craig Shumate; Nai Pongpatana; James W. Yates
    The main objectives of this pilot study were to investigate human ability to: 1) estimate weight of boxes on a lifting task, 2) discriminate among different levels of load, and 3) relate this ability to subjective perception of load heaviness expressed in terms of linguistic descriptors. The effects of color and load differential, defined as a constant weight difference among a series of five boxes, on perception of load heaviness, were also studied. It was shown that the human ability to discriminate among weights of boxes lifted is severely impaired as the load differential decreases below 4 lbs. In addition, as weight of the box exceeds 30 lbs., the difficulty in load differentiation and load estimation, as measured by the number of errors made, significantly increases. This study also suggests that the use of linguistic (verbal) descriptors in the estimation of weights of boxes lifted from the floor to table height, allows for better judgement than the use of numerical values alone.

    Industrial Ergonomics: Occupational Biomechanics

    Three Dimensional Measures of Trunk Motion Components during Manual Materials Handling in Industry BIBA 662-666
      W. S. Marras; L. R. Sudhakar; S. A. Lavender
    The objective of this study was to monitor and document the three dimensional spine motion components experienced during the performance of industrial work that is associated with various risks of low back disorder (LBD). An industrial study was performed that examined on-the-job trunk motions of 64 workers from 13 different industries. Trunk range of motion, velocity and acceleration were documented. Worker anthropometry, health history, external load moments, job satisfaction and risk (identified from OSHA 200 logs) were also recorded for the various jobs. The results identified and quantified those trunk motion characteristics as well as other workplace variables that were associated with high risk jobs. A regression model of job related LBD risk was also created based upon this information. The relationship between these motions and biomechanical loading of the spine as well as means to reduce the risk of LBD in the work place (based upon this study) are discussed.
    Activity Patterns of Several Trunk Muscles during an Asymmetric, Non-Isokinetic Lifting Motion BIBA 667-671
      Carolyn M. Sommerich
    The purpose of this study was to investigate muscle recruitment patterns for a task routinely performed in industry, under conditions which might be encountered in industry rather than in a controlled laboratory setting. Subjects encountered two asymmetric loading conditions (minimal and substantial) and two trunk motion speed conditions (normal and fast) and performed several repetitions of each condition. Electromyographic (EMG) voltage data pertaining to four pairs of trunk muscles were collected for analysis. Thc timing of certain events in each signal (start, peak, and end times of elevated activity) were determined. From these events, networks were constructed which portrayed average muscle recruitment order results which were found to occur under all loading and velocity conditions encountered by the subjects. Only two event-pairs were found to occur consistently for all subjects. Event-pairs which were related to changes in resistance or only one pair was found to occur for all subjects.
    Optimization Techniques in Occupational Biomechanics BIBA 672-676
      Ashraf Genaidy; Abdolazim Houshyar
    In most detailed representations of joint mechanics incorporating the effects of muscle forces in biomechanical models the number of available force-carrying structures crossing the joints are in excess of the number of available equilibrium of the joint. Unless one makes gross anatomical and functional simplifications, the mathematical description of joint mechanics involves an undetermined set of equations. Different approaches have been taken by researchers to solve this statically indeterminate problem, but the intuitive reasonableness of optimization in body function has led investigators to use numeral optimization procedures in the prediction of muscle force activity. This paper reviews and evaluates various optimization techniques applied to occupational biomechanics.
    Safety of Back! What is the Margin? BIBA 677-681
      Shrawan Kumar; Anil Mital
    Despite many efforts to control low back pain problem it still continues to be a concern. Since the causation of low back pain is under multifactorial control, it will always be the factor most vulnerable at a given time which will determine safety. The present study is an integrative inferential synthesis of the published work to discern the margin of safety. An attempt has been made to conclude, on the basis of objective evidence, an all encompassing criteria to ensure system safety. Though psychophysical approach integrates biomechanical and physiological variables the role of sensory conditioning needs to be addressed.

    Industrial Ergonomics: Industrial Ergonomics Case Studies

    Physical Demands of Bakery Workers BIBA 682-686
      T. L. Doolittle; Barton Daniel
    Job analyses were conducted at three bakeries of a West Coast company to determine the metabolic and strength demands imposed upon the workers. The physically demanding tasks were consolidated into four job families. Masses, distances, frequencies and other data were obtained. From these it was determined that individuals were working at 3.5 to 4.0 METs continuously with peek efforts reaching 5 METs. Strength requirements exceeded the NIOSH action limit for some tasks. Preassignment screening standards were recommended as an administrative control.
    How Can Manufacturing Human Factors Help Save a Company: Intervention at High and Low Levels BIBA 687-689
      C. G. Drury; B. M. Kleiner; J. Zahorjan
    Now that manufacturing has become a respectable topic in industry, an obvious question is how human factors/ergonomics can contribute to the improvement of manufacturing. The traditional route for ergonomics intervention has been a Project route, with a set of objectives agreed between the human factors engineer and people within the company. Projects, however, do not ask the question of whether human factors intervention is likely to have an impact on the company's strategic objectives, for example, remaining in the manufacturing of a particular product.
       Case studies in a variety of industries are used to contrast the project approach with a more strategic approach. It is concluded that the project may represent sub-optimization in that a successful outcome of the project may have no impact upon company survival without a careful examination of the strategic plans of the company.
    An Ergonomic Evaluation of Customer Service Operations -- A Case Study BIBA 690-693
      Robert E. Thomas; Jerome J. Congleton; William H. Horsford
    Computer equipment repair services are a major and highly competitive industry. An ergonomic evaluation of the activities, methods, facilities and tools used by individual field service representatives of a major computer manufacturer were studied. Results indicated that good ergonomic interventions could reduce employee injuries while increasing productivity and rate-of-return on operations.
    Ergonomics Analyses of the AT&T Operator Service Position System BIBA 694-697
      Bahador Ghahramani
    The Operator Services position System (OSPS) is an advanced Ergonomically sound workstation designed to furnish AT&T operators with enhanced call processing facilities. The predecessor for the OSPS system originated as the Traffic Service Position System (TSPS) about 40 years ago and replaced the manual corded operator positions. At that time, the TSPS represented a significant improvement for the operator working environment. Ergonomics advancements in the past 40 years since the TSPS design, have been applied to the replacement OSPS.
       Additional features were provided to the TSPS system in 1986. The Computerized Position Information System (COMPIS) is an auxiliary system designed to enhance operator work efficiency and productivity. The COMPIS system is the old TSPS system augmented by a Video Display Terminal (VDT) and a movable keyboard with a long cord.
       This COMPIS "add-on" was acceptable when COMPIS use required only 10% of the operators' 8-hour working day. The COMPIS was so successful that usage quickly climbed to 50%. COMPIS equipment was an interim system intended to enhance operator capabilities until the new Operator Services Position System (OSPS) is installed in late 1990.
       The primary objective of this paper is to discuss the significant Ergonomics considerations of this system and describe their applications within the communications industry. The Ergonomic goals of AT&T are: development of procedures to be utilized for system feedback and keying of calls; and, provision of a console and screen display layout that can support the maximum use of Human Factors principles as they apply to the operators' duties.

    Industrial Ergonomics: Hand/Wrist Characteristics

    Ranges of Motion in the Human Wrist BIBA 698-702
      Regina M. Neese; Stephan Konz; Mark Reams
    Measurements of wrist ranges of motion were made for 40 males and 83 females; only 1 subject worked in a factory. Age ranged from 16 to 88. Flexion was 57° for females and 56° for males; extension was 53° for females and 50° for males. Adduction was 24° for both females and males; abduction was 55° for females and 57° for males. Pronation was 139° for females and 130° for males; supination was 89° for females and 78° for males. Pronation increased significantly with age ² = 21%).
    Development and Evaluation of Regression Models for the Prediction of Human Torque Strength Applied in the Prone Position BIBA 703-707
      Thomas Weaver; Subramanian Deivanayagam
    This paper describes an experimental investigation conducted to develop and test predictive models for human torque strength in simulated maintenance tasks performed in the prone position. Eight linear regression models were developed for the prediction of human torque strength applied with a socket wrench while lying in the prone position. The models utilized anthropometric and strength data from 40 subjects in conjunction with task point location variables in their formulation. The predictability of each model was evaluated by comparing the observed and predicted torque values from 10 additional subjects.
    Glove Size and Material Effects on Task Performance BIBA 708-712
      Yuxiang Chen; David J. Cochran; Ram R. Bishu; Michael W. Riley
    Two experiments were conducted to measure the effect of glove size and material on task performance. The first experiment tested the glove size and material effects on a maximum torque exertion task while the second experiment tested the glove size and material effect on a small parts assembly task. The results of the first experiment showed that for the maximum exertion task, the glove size had no significant effect while the glove material did have a significant effect. For the assembly task the results indicated that glove size and material combination may be important to performance.
    The Use of Force Sensing Resistors in Ergonomic Tool Design BIBA 713-717
      Gerald L. Fellows; Andris Freivalds
    With more leisure time and greater reliance on the fix-it-yourself approach, more and more people, will be using hand tools. The proper ergonomic design, as related to grip force exerted and fatigue generated, is an important consideration for these tools. To measure grip force distribution, Force Sensing Resistors were calibrated appropriately, placed on two different grip type (wood and foam) and interfaced to a personal computer. Results of a lopping task indicated a very uneven distribution in grip pressure. In all cases, grip force decreased with time while forearm flexor muscle EMG increased with time, indicating fatigue buildup. Forearm EMG for the foam grip was significantly lower than for the wooden grip. Most subjects also strongly preferred the foam grip.

    Industrial Ergonomics: Prevention of Cumulative Trauma Disorders

    Validation of a Hand/Wrist Electromechanical Goniometer BIBA 718-722
      Richard W. Schoenmarklin; William S. Marras
    This paper describes a new hand/wrist electromechanical goniometer that measures wrist angle, velocity, and acceleration in the radial/ulnar and flexion/extension planes. The research objectives of this paper were to validate the angle and motion measures from this goniometer. The results of this research show that the coefficient of variation of the angle measured by the goniometer and the angle measured by a video-based Motion Analysis system was 3%. By smoothing the voltage data three times in software, the goniometer estimated well the velocity and acceleration measures under controlled dynamic conditions. Three smoothing repetitions appear to be the best smoothing regimen for the goniometer because it reduced signal noise while still maintaining the sensitivity of the velocity and acceleration output. Overall, the goniometer is an easy-to-use, accurate system of measuring wrist angle and motion. This goniometer will be used to build a database of wrist motion in industrial tasks.
    Exercise as a Prophylactic Device Against Carpal Tunnel Syndrome BIBA 723-727
      Thomas L. Williams; Leo A. Smith; Richard T. Herrick
    The null hypothesis that participation in an on-the-job strength and flexibility exercise program typical of those directed toward prevention of musculoskeletal stress has no prophylactic effect against carpal tunnel syndrome when used as an intervention measure in a population of female garment workers was examined. Grip strength, Phelan's test results, and hand/wrist thermograms obtained by liquid crystal thermography were taken on an experimental group of female employees in a southern garment manufacturing facility before, after five weeks, and after ten weeks of an exercise program and compared with data obtained from a control group. Although the test results suggested the exercise program may have had some benefit, the null hypothesis could not be rejected. An engineering economic analysis, assuming the exercise program was effective and implemented throughout the corporation, indicated the payback period would be approximately eleven years thus casting doubt on its economic efficacy also.
    A Study of Several Performance Measures of Workers with Carpal Tunnel Syndrome BIBA 728-732
      Jeffrey E. Fernandez; Don E. Malzahn; Robert J. Marley; Alan R. Bonebrake
    Objective measures of anthropometry, strength, range-of-motion, muscle activity, and task performance, and subjective ratings of pain were observed in a group of individuals diagnosed with carpal tunnel syndrome (CTS). These measures were compared to a control population showing no symptoms of CTS. Results indicate that individuals with CTS had significantly lower values on some strength tests, less range of motion on several measures, and reduced performance on a simulated task than did the control group. Ratings of pain and distress for the CTS group were also significantly higher than the control group. Occupational and personality factors associated with the CTS group were also identified and discussed.

    Industrial Ergonomics: Determining Human Capacities in Industrial Ergonomics

    Evaluating the Effects of Automation on the Human Operator BIBA 733-736
      Brian M. Kleiner; Colin G. Drury; Joseph Sharit; Sara J. Czaja
    This study was designed to evaluate the symbiosis of human-machine systems with varying levels of automation. This paper focuses on the protocol methodology employed in the study. The approach required the use of both qualitative and quantitative techniques to derive a comprehensive evaluation of the human-machine system. Protocol Analysis supported by ethnographic software was used to evaluate the verbal transcripts. A qualitative process of code mapping and analysis was developed. The Modified Cooper-Harper scale was used to evaluate mental workload and objective measures of performance provided quantitative data of the system. The results confirmed the usefulness of a proposed classification scheme for human-machine systems. Using the methodology, human capabilities could be assessed against system demands for various configurations of a human-machine system. The importance of understanding the human's role in increasingly automated systems was again demonstrated.
    Predictive Models of Hand Torque Strength for Circular Electric Connectors BIBA 737-741
      S. Keith Adams; Xianqiang Ma
    Maintenance and its associated costs have become a serious problem for nearly all military and civilian organizations using aircraft and other complex hardware. This paper describes extensions of development work designed to provide basic elemental task configuration versus strength data for tightening and loosening circular electrical connectors by proposing a mathematical formulation of the problem, showing a model relating hand torque strength to specific task variables and dimensions, and giving the results of predictive tests in which predicted hand torque strength was compared against values obtained in a comprehensive statistically balanced set of hand torque strength tests. Results strongly support the theoretical basis and structure of the predictive model and indicate directions for refinement as more data are obtained in future applications.
    Accuracy of a Ratio-Estimation Method to Set Maximum Acceptable Weights in Lifting Tasks BIBA 742-744
      Stephen J. Morrissey; Alvah C., Jr. Bittner
    This study examined the accuracy with which trained and conditioned females could set Maximum Acceptable Weights (MAWs) using ratio estimation. Examined were two lifting ranges, floor-to-knuckle and knuckle-to-shoulder, and four lift frequencies (lifts every 9-, 20-, 60-, and 120-seconds). In each of the eight conditions subjects set the MAW using the method of adjustment. Immediately after the MAW had been set, the task was changed, performed for a few cycles, and rated using ratio estimation. This rating was used to establish an estimated MAW for the second lifting task. On a later day, the MAW was set for the second task using the method of adjustment and the MAW for the original task estimated with ratio estimation. This allowed comparison of the accuracy of MAWs set by psychophysical and ratio estimation methods as affected by the frequency and lifting zone of the standard task. Consistent with previous research there were significant effects on the MAW due to frequency of lift and the lift range. Also, and importantly, there were no significant differences between MAWs set by ratio estimation and by the traditional method of adjustment (p>0.6). This indicates that ratio estimation is an accurate method to quickly establish MAWs for a variety of lifting tasks. This indicates that MAWs for entire classes of lifting tasks can be quickly and accurately determined with ratio estimation.
    Human Lifting Strength in Different Postures BIBA 745-749
      C. Chomcherngpat; P. Mandhani; C. Lum; C. Martin
    A laboratory study was conducted to determine static lifting strengths on 13 males and 12 females from 18 to 28 years of age. Using the strength monitor, the average strength and peak strength were measured in four different postures: standing, sitting, lying on stomach with elbows support, and without elbow support. Five sets of data were collected at constant heights. There was a significant difference in lifting strengths between standing lifts and lying on stomach without elbow-support postures; maximum lift occurred in the standing position. It was found that there was no significant difference in lifting strengths between sitting and lying on stomach with elbows support. The average female strengths were found to be about 49% to 55% of male subjects in all postures.

    Industrial Ergonomics: Panel

    A Round-Table Discussion of Ergonomic Issues in the Meat-Packing Industry BIB 750-751
      Deven Scott; David J. Cochran; Dan MacLeod; Dan Habe; Ulrika Wallersteiner; A. K. Arnold; Sharon Falkenberg; Thomas J. Albin

    International Technology Transfer: Dimensions for International Technology Transfer

    Training: An Essential Aspect of Human Factors in Technology Transfer to Developing Countries BIBA 752-756
      Michelle M. Robertson; Eric P. Di Giovanni
    The creation and planning of a successful international training program is dependent upon the establishment and implementation of a systematic approach or process which integrates the educational goals, with the development needs for the country. This paper examines various planning processes, approaches, techniques and models of training systems and the critical elements necessary to design, develop and implement a cost-effective training system in developing countries. General alternatives and possible options for development and improvement of international training systems, which incorporate unique characteristics, socio-cultural factors and cultural mores are presented in six models.
    Appropriate Technology Transfer to the Developing World: Microcomputers in Colombian Firms BIBA 757-760
      Mary McEniry
    This paper discusses the aspects that comprise the appropriate transfer of microcomputers to small and medium-sized Colombian manufacturing firms. The paper draws on the experience gained from an 18-month study carried out in Colombia among small and medium-sized manufacturing firms. The paper argues that the issue of appropriateness lies more in how to use" microcomputers rather than "whether or not" to use them. International mechanisms that could improve the "how to use" microcomputers are identified and discussed and the creation of an international center for the appropriate transfer of microcomputers to the developing world proposed.
    Lesson Prototyping in Multinational Computer-Based Training Program Development BIBA 761-764
      Bruce C. Lierman
    Many training projects seek to obtain the maximum return from investment in computer based training (CBT) by adapting the training materials to all potential trainees in diverse nations and settings. Lesson prototyping, especially modeling of the interactivity between trainee and the program, provides a means to confirm the effectiveness of the program before investments are made in preparing multi-cultural presentation materials. The interactivity model enables program designers to gather data on trainee interaction at the earliest possible stage of development. Data collected from the trainee and expert interaction with the interactivity model is used to modify the structure of the presentation and insure that all training requirements have been addressed. Data collection from an interactivity model is particularly valuable in determining assistance requirements and cultural factors in the program structure early in the development process. This methodology may help to reduce overall training development costs and lead time.
    Requisite Variety: A Concept to Analyze the Effects of Cultural Context for Technology Transfer BIBA 765-769
      Gail Demel; Najmedin Meshkati
    The Law of Requisite Variety states that "the system must possess as much regulatory variety as can be expected from the environment" (Ashby, 1957). This law may have some implications for culture. Specifically, the four cultural dimensions by which national cultures differ (as proposed by Hofstede, 1980a): Power Distance, Uncertainty Avoidance, Individualism-Collectivism, and Masculinity-Femininity influence Requisite Variety depending on the country to which the technology is transferred. Therefore, it is proposed in this study that Requisite Variety can be used as a concept to systematically investigate the influence of culture for technology transfer. This approach constitutes the incorporation of Human Factors considerations in technology transfer, as stated by Meshkati (1986 and 1989b) and Wisner (1985).