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

Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting 1993-10-11

  1. HFS 1993-10-11 Volume 2
    1. INDUSTRIAL ERGONOMICS: Kinematics of the Trunk and Wrist
    2. INDUSTRIAL ERGONOMICS: Biomechanical Risk Factors
    3. INDUSTRIAL ERGONOMICS: Spine Loading and Postural Stability
    4. INDUSTRIAL ERGONOMICS: Upper Extremity Strength and Biomechanics
    5. INDUSTRIAL ERGONOMICS: Strength
    6. INDUSTRIAL ERGONOMICS: Panel
    7. INDUSTRIAL ERGONOMICS: Measurement
    8. INDUSTRIAL ERGONOMICS: Quantitative Applications
    9. INDUSTRIAL ERGONOMICS: Cognitive Biomechanics
    10. INDUSTRIAL ERGONOMICS: Application Research
    11. INDUSTRIAL ERGONOMICS: Industrial Ergonomics Potpourri
    12. MEDICAL SYSTEMS AND FUNCTIONALLY IMPAIRED POPULATIONS: Human Factors in Health Care and Universal Design
    13. MEDICAL SYSTEMS AND FUNCTIONALLY IMPAIRED POPULATIONS: Panel
    14. ORGANIZATIONAL DESIGN AND MANAGEMENT: Panel
    15. ORGANIZATIONAL DESIGN AND MANAGEMENT: A Macroergonomics Toolbox
    16. ORGANIZATIONAL DESIGN AND MANAGEMENT: Macroergonomics Perspectives on the Same Old Safety Problems
    17. PERSONALITY AND INDIVIDUAL DIFFERENCES IN HUMAN PERFORMANCE: Individual Differences in Personality and Human Performance
    18. PERSONALITY AND INDIVIDUAL DIFFERENCES IN HUMAN PERFORMANCE: Panel
    19. SAFETY: Warnings and Compliance
    20. SAFETY: Contemporary Safety Issues in Driving
    21. SAFETY: Arnold M. Small Lecture in Safety
    22. SAFETY: Perception of Risk and Warning Effectiveness
    23. SAFETY: Industrial Safety and Personal Protection
    24. SAFETY: Environmental and Nuclear Power Safety
    25. SPECIAL SESSIONS: Demonstrations
    26. SYSTEM DEVELOPMENT: Viewing Complexity in System Development
    27. SYSTEM DEVELOPMENT: Panel
    28. SYSTEM DEVELOPMENT: Developing Human Factors Guidelines for Intelligent Vehicle/Highway Systems: First Progress Report
    29. SYSTEM DEVELOPMENT: Design Issues in System Development
    30. SYSTEM DEVELOPMENT: Perspectives on Decision Analysis for Decision Support System Design
    31. SYSTEM DEVELOPMENT: Panel
    32. TEST AND EVALUATION: Usability Evaluations
    33. TEST AND EVALUATION: T&E Theory and Application
    34. TEST AND EVALUATION: Panel
    35. TEST AND EVALUATION: The Measurement and Evaluation of Collective Unit Training and Performance
    36. TEST AND EVALUATION: T&E in Systems Evaluation
    37. TRAINING: Training Interventions for Complex Skills
    38. TRAINING: Training for Team Coordination and Decision-Making Effectiveness: Theory, Practice, and Research Directions
    39. TRAINING: Panel
    40. TRAINING: Training Issues in Aviation
    41. TRAINING: Issues in Training Problem Solvers
    42. VISUAL PERFORMANCE: Preattentive Processing in Visual Search
    43. VISUAL PERFORMANCE: Information Processing and Formatting
    44. VISUAL PERFORMANCE: Visual Performance Using HUDS and HMDS
    45. VISUAL PERFORMANCE: Visual Psychophysics and Methods
    46. VISUAL PERFORMANCE: Panel
    47. VISUAL PERFORMANCE: Attention and Workload

HFS 1993-10-11 Volume 2

INDUSTRIAL ERGONOMICS: Kinematics of the Trunk and Wrist

Wrist Motions in Industry: Variance between Jobs and Subjects BIBA 649-653
  Richard W. Shoenmarklin; William S. Marras
Ergonomists assume that they can design out injurious postures and motions with engineering controls by guiding the worker to use the preferred, less injurious motions. The variance between workers performing tasks in ergonomically-designed jobs is assumed to be dominated by the variance between jobs. However, little research exists that quantified whether this assumption is valid.
   The present study examined the wrist motions of 40 industrial workers who performed highly repetitive, hand-intensive jobs of low and high risk of cumulative trauma disorders (CTDs). The position and angular velocity and acceleration of these workers' wrists were measured in all three planes (radial/ulnar, flexion/extension, pronation/supination) with goniometry. The results of this study show that for all the kinematic variables, the variance between subjects within jobs accounted for a substantial, and often majority, amount of variance. The results of this study demonstrate that ergonomists should consider the variability in motion patterns between workers when designing existing or new jobs and also should monitor at least two subjects per job in quantitative surveillance studies of wrist motion.
Workplace Factors and Trunk Motion in Grocery Selector Tasks BIBA 654-658
  Thomas R. Waters
A project was recently undertaken by the National Institute for Occupational Safety and Health (NIOSH) to evaluate the physical demands of warehouse grocery selectors. A small study was designed to collect workplace measures and trunk motion data to determine the level of physical stress associated with a particular lifting task. A subset of these measures was used to apply the model developed by Marras et al. (1993) to predict if warehouse grocery selectors were at high risk for LBD.
Dynamics of Trunk Performance during One-Handed Lifting BIBA 659-663
  W. Gary Allread
This study investigated the biomechanical effects of using one hand to perform a materials handling tasks. Subjects were asked to lift a box from a lower to an upper platform using either one or two hands. Three weight levels and four lower platform positions were examined. Subjects wore a back monitor (from which was calculated motion components in the three cardinal planes of the body), stood on a force plate, and were asked to give a rating of perceived exertion for each lift. Results of this study showed that one-handed lifts produced significantly higher ranges of lumbar spine motion in the lateral and transverse planes and greater flexion in the sagittal plane. Back motion risk factors previously found to be associated with high risk of injury jobs all were significantly higher for one-handed lifts. Two-handed lifts, however, produced overall faster motions in the sagittal plane, and equal or larger acceleration and deceleration magnitudes in all planes of motion. Results from the psychophysical measure found no differences in perceived exertion between one- and two-handed lifts. These results suggest that one-handed lifts load the spine more than two-handed lifts due to the added coupling and increase one's risk of suffering a low back disorder. This study also agrees with previous research finding that increased load weight and lifting from asymmetric positions increase risk of low back injury.
Variation in Trunk Mobility throughout the Work Day BIBA 664-668
  Fadi A. Fathallah; Patrick L. Wright; William S. Marras
Low back disorders have been a major concern for both industries and the public in general. Diurnal variation in trunk flexibility has been previously observed and quantified in terms of range of motion. It was hypothesized that decreased disc height as the day progresses allows the spinal ligaments to slacken, resulting in an increase in the range of motion (flexibility) and possible reduction in risk of injury. Evidence suggests that this risk may be accentuated under dynamic motions of the spine. This experiment focused on observing the change in dynamic components of trunk flexibility (trunk mobility) as a function of time of the day. Trunk motions of twenty-one male participants were obtained at three specific times of the day using a tri-axial electrogoniometer. No variation in trunk range of motion in any of the cardinal planes was observed. However, velocity and acceleration in the sagittal plane showed significant variations, suggesting the re-examination of the "slack ligaments" hypothesis. This study asserts that identifying flexibility by only its static component, range of motion, gives only partial information. Industrial injuries occurring in the early morning hours may be a result of insufficient trunk mobility. The relation between trunk mobility and back injury incidence rates should be further investigated.

INDUSTRIAL ERGONOMICS: Biomechanical Risk Factors

Exposure Assessment of Biomechanical Stress in Repetitive Manual Work using Spectral Analysis BIBA 669-673
  Robert G. Radwin; Mei-Li Lin; Thomas Y. Yen
Theory for a quantitative exposure assessment strategy is presented for measuring physical stress associated with manual tasks containing repetitive motion, postural stress, and forceful exertions. Physical stress is measured directly using electrogoniometers for particular motion, and sensors or electromyography are used for assessing forceful exertions. A method is described for reducing the large quantities of biomechanical data that can be recorded for repetitive manual work into quantifiable metrics based on recognized exposure factors, including repetitiveness, postural stress, forcefulness, and duration. A frequency domain approach is used for averaging elemental data from repetitive cycles. This paper shows how parameters for frequency-weighted filters may be developed from psychophysical data for equivalent discomfort levels. Low force repetitive wrist flexion was used as an example of the feasibility for implementing this approach. Applications of this theory include assessing exposure to physical stress in a manner analogous to the way sound level meters are used for measuring exposure to acoustic noise. A suitable data reduction method is necessary for conducting large scale detailed epidemiological investigations of cumulative trauma disorder risk factors. Development of frequency-weighted filters based on human response to stress at different frequencies may make it possible to establish quantitative exposure limits.
Fatigue in High and Very High Frequency Manual Lifting, Lowering and Carrying and Turning BIBA 674-678
  Anil Mital; Hamid Founooni-Fard; Max L. Brown
This paper presents the results of a study undertaken to determine the perceived exertion and physiological responses of highly trained and experienced workers to high (up to 16 repetitions per minute) and very high frequency (above 16 repetitions per minute) manual lifting, lowering, and carrying and turning tasks. The results indicate that workers engaged in such highly repetitive and physically demanding tasks operate at work loads that may clearly be considered physically fatiguing and unacceptable by the current physiological design criteria. The workers, however, perceived these exertions to be generally acceptable. The physiological responses of the workers are also compared with previous and recommended physiological design criteria.
Work Sampling as a Method for Assessing CTDs BIBA 679-682
  David Mahone
Work sampling is proposed as a method for evaluating aggregate risks for cumulative trauma disorders in jobs. The approach assumes that an assessment of cumulative trauma disorder (CTD) risk factors within individual tasks has been made, and can be used in conjunction with the resulting estimates of proportion of time spent per task or activity to arrive at an overall estimation of CTD risk for the job. Important advantages of work sampling include that it estimates the availability of rest and recovery time within jobs, that the method can be applied to both cyclical and noncyclical jobs, and that small, practical samples may provide reasonable estimates in many cases. A case study utilizing work sampling in a workers compensation carpal tunnel syndrome (CTS) claims investigation using a single day sample interval is presented. Results suggest little or no CTD risk, a finding that was supported by historical evidence from a large population of workers (27,200) performing the same job. Only .0000025% of workers had reported a CTD over a period of 3 years. While support for causation of CTD was not found, the method identified a probability of aggravation of a possible pre-existing condition, which is also compensable. Details regarding the studied job are provided. The use of a work sampling method to assess CTD risks is discussed.
A Catastrophe Theory-Based Model for Quantification of Risk of Low Back Disorders at Work BIBA 683-687
  Waldemar Karwowski; William S. Marras
This paper discusses applications of the catastrophe theory in the dynamic modeling of occupational low back disorders, and offers a framework for conceptualization of such disorders in view of the elementary cusp catastrophe models. It was proposed that low back disorders due to manual lifting should be considered as a discontinuous phenomenon, reflecting dynamic changes in the state of human musculoskeletal system, which are dependent upon the combination of human strength abilities, muscular fatigue and endurance, spinal loading tolerance, as well as dynamic equilibrium between these variables. The behavior of the proposed cusp-catastrophe based model for the risk of LBDs due to manual lifting jobs was examined based on empirical data collected in industry.

INDUSTRIAL ERGONOMICS: Spine Loading and Postural Stability

Trunk Muscle Activations while Resisting Asymmetric Loads in a Laterally Bent Trunk Posture BIBA 688-692
  Steven A. Lavender; Ing-Ho Chen; Jordan Trafimow; Gunnar B. J. Andersson
Asymmetric material handling frequently results in lateral bending of the torso. Each of these factors have been linked via epidemiological investigations to the incidence of low back disorders (LBD). Very little literature is available which describes the response of the trunk muscles in situations which would be analogous to handling materials while bent to the side. Such activities are observed frequently in industrial settings, especially during the initial and final portions of a lift. The objective of the current study was to describe the internal response of the trunk muscles as asymmetric loads were applied to the laterally bent torso. Specifically, this investigation quantified the electromyographic activities (EMG) of 8 trunk muscles under conditions where the trunk was isometrically loaded while the trunk was maintained in a 20 degree laterally bent posture. Moments with a magnitudes of 20 and 40 Nm were applied to fifteen subjects. The direction of the external moments was varied in 30 degree increments completely around the subjects. The EMG data indicates that the muscles showed the greatest activity when they were in opposition to the load's sagittal and frontal plane moment. The muscle showing the largest response was the External Oblique. Significant activity was also observed under conditions in which muscles were creating an antagonistic moment in either the sagittal plane, the frontal plane, or in both planes.
Optimization-Based Biomechanical Evaluation of Isometric Exertions on a Brake Wheel BIBA 693-696
  Christian A. Johnson; Jeffrey C. Woldstad
A static three-dimensional low-back biomechanical model was developed to estimate the levels of compressive force on the L3/L4 spinal joint during an experiment that simulated wheel turning. We recorded three-dimensional body posture and the resultant forces at the hands for analysis by the model. The model employed a standard link analysis procedure to resolve the external forces acting on the body to a resultant moment about L3/L4. The model then implemented an optimization algorithm to estimate the internal lumbar muscle forces generated to resist the external forces. The muscle forces and external forces were added to arrive at a prediction of compressive force at L3/L4. The experiment investigated the effects of general body posture, left hand grip, gender, and hand brake torque level upon predicted compressive force at L3/L4. A repeated measures analysis of variance (ANOVA) revealed all but one main effect and some interaction effects to be significant at p<0.05. Average predicted L3/L4 compressive forces at maximum wheel torque levels ranged from 1644N for females to 6926N for large males.
Postural Stability while Holding Loads of Various Postures BIBA 697-700
  Mary Ann Holbein; Mark S. Redfern
Stability while handling loads is an important issue in the prevention of injuries. This study investigated the effects of load positioning on recovery from an unexpected balance disturbance while standing upright holding loads. Fifteen subjects were tested while holding a box in one of five postures. An empty box and a 25 lb box were tested. Subjects stood on a posture platform while perturbations of the supporting surface were induced. Postural sway was recorded via center of pressure displacements calculated from three dimensional foot forces. It was found that laden standing with the heavier load resulted in increased sway magnitude and slower sway velocities than unladen standing. The load position also affected stability. Raising the center of gravity of the body-and-load system appears to increase sway. These results require consideration when designing safe material handling tasks, especially if the supporting surface is unstable or if slip potential is present.
Slip Potentials on Ramps BIBA 701-704
  Mark S. Redfern; Edward J. McVay
Falls are a major cause of injuries at work, in public places and at home. In over 50 percent of falling accidents, slips led to the injury. Ramps have the potential to be particularly hazardous with regards to slips and falls since higher shear forces are created. The purpose of this study was to determine the effect of ramp angle on slip potential at the feet during downward and upward gait. This was accomplished by investigating the relationship between the horizontal and vertical foot forces during gait as a function of ramp angle. A ramp was designed and built which incorporated a force plate. Foot forces were measured while subjects walked up and down the ramp. The ramp angle was varied from 0 to 20 degrees in 4 degree intervals. Normal forces were divided into the shear forces, thus calculating a "required" coefficient of friction (RCOF) for the entire trial. The results showed shear forces increase both in magnitude and duration as ramp angle is increased. The RCOF also increased as ramp angle increased. The maximum RCOF for each trial increased almost linearly as the ramp angle was increased ² =.92;p<.01), with levels often over 0.6 at angles of 20 degrees. Most guidelines for ramp design suggest a surface with a minimum COF of 0.5; however this study indicates that high ramp angles can generate RCOF values greater than this recommended level. Thus, the guidelines may be too low and a higher surface COF necessary.

INDUSTRIAL ERGONOMICS: Upper Extremity Strength and Biomechanics

Coactivity Effects upon Carpal Tunnel Contact Forces BIBA 705-709
  Sue A. Ferguson; Fadi A. Fathallah; Kevin P. Granata; Jung Y. Kim; William S. Marras
Contact force on the carpal tunnel structures due to flexor tendon forces have been identified as an important contributor to the compression of the median nerve. Therefore, a pilot study was conducted to assess the increase ln carpal contact force due to the antagonistic coactivity of the finger extensor muscles. Surface EMG activities of the superficial finger flexor and extensor muscles of four subjects were measured during several isometric power grip exertions at seven different wrist angles. The results showed that a linear relation between EMG and muscle force holds under the prescribed isometric conditions. An EMG-assisted model was developed to predict tensile forces in an equivalent flexor tendon. For a given angle, the model predicts increased tensile force in the flexor tendon with increased extensor (antagonist) coactivity in response to isometric grip exertions. It was found that if one accounts for muscle coactivity, predisted force in the flexor tendons would be as much as 33% greater than force predicted by models which neglect coactivity. This increase would also be observed in carpal contact force since this force is linearly related to the flexor tendon force. Models that neglect coactivity severely underestimate flexor tendon forces and consequently contact forces in the carpal tunnel.
A Finger Model with Constant Tendon Moment Arms BIBA 710-714
  Koo-Hyoung Lee; Karl H. E. Kroemer
A kinematic finger model was developed with the assumption that the tendon moment arms at the finger joints were constant, and that the finger moved in the sagittal plane. Equations of static equilibrium for the model, derived using the principle of virtual work, were indeterminate. The number of variables was reduced based on the muscular activities in finger movements. The finger strengths were computed from the equilibrium equations, and mathematically expressed as functions of finger positions, tendon moment arms, and lengths of phalanges. Experiments were performed to measure finger strengths, and the measured finger strengths were compared to the computed results.
Quantification of Hand Grip Force under Dynamic Conditions BIBA 715-719
  Katherine R. Lehman; W. Gary Allread; P. Lawrence Wright; William S. Marras
A laboratory experiment was conducted to determine whether grip force capabilities are lower when the wrist is moved than in a static position. The purpose was to determine the wrist velocity levels and wrist postures that had the most significant effect on grip force. Maximum grip forces of five male and five female subjects were determined under both static and dynamic conditions. The dominant wrist of each subject was secured to a CYBEX II dynamometer and grip force was collected during isokinetic wrist deviations for four directions of motion (flexion to extension, extension to flexion, radial to lunar, and ulnar to radial). Six different velocity levels were analyzed and grip forces were recorded at specific wrist positions throughout each range of movement. For flexion-extension motions, wrist positions from 45 degrees flexion to 45 degrees extension were analyzed whereas positions from 20 degrees radial deviation to 20 degrees ulnar deviation were studied for radial-ulnar activity. Isometric exertions were also performed at each desired wrist position. Results showed that, for all directions of motion, grip forces for all isokinetic conditions were significantly lower than for the isometric exertions. Lower grip forces were exhibited at extreme wrist flexion and extreme radial and ulnar positions for both static and dynamic conditions. The direction of motion was also found to affect grip strength; extension to flexion exertions produced larger grip forces than flexion to extension exertions and radial to ulnar motion showed larger grip forces than ulnar to radial deviation. Although, males produced larger grip forces than females in all exertions, significant interactions between gender and velocity were noted.
Use of the Actigraph for Objective Quantification of Hand/Wrist Activity in Repetitive Work BIBA 720-724
  Katharyn A. Grant; Traci L. Galinsky; Peter W. Johnson
Valid and reliable measures of hand/wrist activity are needed to address the relationship between work tasks and the development of upper extremity musculoskeletal disorders. The utility of the actigraph for measuring wrist activity in manual work was examined in this study. Ten grocery cashiers and four non-cashier retail workers wore actigraph monitors on both wrists and the left ankle during their normal work activities. Work activities were periodically observed and recorded on videotape. Data recorded by the actigraphs were matched against observational data. The results indicated that actigraphy was effective in detecting significant work-related variations in physical activity in the three limbs studied. Compared to traditional observational procedures, actigraphy represents a cost-effective approach for obtaining objective and quantitative information about the intensity and duration of work over long time periods. Traditional observational procedures, however, are necessary to provide additional information needed for a complete job analysis (e.g., postural data). Continuous activity recordings can be used in conjunction with sampling protocols to examine the relationship between work-related physical activities and musculoskeletal trauma.

INDUSTRIAL ERGONOMICS: Strength

Maximum Lifting Capacity in Single and Mixed Gender Three-Person Teams BIBA 725-729
  Marilyn Sharp; Valerie Rice; Bradley Nindl; Tania Williamson
Little information is available regarding isoinertial lifting ability in teams of two or more people. The relationship between the sum of individual lifts and the lifting capacity of a three person team was examined. Eleven men and ten women were randomly combined into 18 teams for each of the following four combinations: three men (3M), three women (3W), two men with one woman (2M&1W), and one man with two women (1M&2W). While the absolute load lifted from floor to knuckle height decreased with a decrease in the number of males on the team, team lifting strength as a percentage of the sum of individual lifting strength was generally higher for single gender teams (91.0% for 3W and 85.0% for 3M) than for mixed gender teams (82.7% for 1M&2W and 74.4% for 2M&1W).
Wheel-Turning Strength for Four Wheel Designs BIBA 730-734
  Mark L. McMulkin; Jeffrey C. Woldstad; Paul B. McMahan; Timothy M. Jones
This paper reports the results of an experiment to evaluate the isometric wheel turning strength of 12 male and 12 female subjects using four different wheel designs. Three of the wheels investigated were new designs developed specifically for this study, while the fourth was a wheel currently used on many railroad car hand brakes. The three new designs considered were a cylindrical tube (4.3 cm in diameter), a cylindrical tube (2.5 cm in diameter) with spheres mounted along the edge, and a circular zig-zag design. Strength data were collected using a mock-up of the ladder and platform arrangement found on most railroad hopper and box cars. The task simulated the final tightening exertion required to secure railroad car hand brakes. Strength capabilities were measured using two methods: 1) a three second average during a six-second trial; 2) the peak reached on a separate trial in which subjects did not sustain an exertion. Results showed that the torque generated by the subjects was highest for the zig-zag design, followed in order by the wheel with the spheres, the cylindrical wheel, and the standard wheel; average torque values were 191 Nm, 147 Nm, 132 Nm, and 95 Nm, respectively. The average strength values (three-second average) for six-second maximum exertions produced lower average torque values (122 Nm) than the ramp to maximum exertion (161 Nm).
Determination of the Maximum Acceptable Weights of Lifting and Lowering using the Direct Estimation Method BIBA 735-738
  F. Aghazadeh; H. Lu; S. J. Morrisey
The maximum acceptable weights of lifting and lowering were determined using the direct estimation method. Five task frequencies (1, 2, 4, 6, and 8 handlings per minute) were studied. Both lifting and lowering were fixed at knuckle-shoulder height. A base load for each individual subject was first established using the psychophysical approach. The direct estimation method was then applied. The results revealed that task frequency exerted a significant role in the variation of the data. The type of tasks (lifting and lowering) also significantly affected the maximum acceptable capacity performing the tasks. The study shows that the direct estimation method is a faster and feasible way to determine the maximum acceptable weight that an individual can handle.
Evaluation of Limiting Strength Constraints in a Comprehensive Biomechanical Model BIBA 739-743
  Carter J. Kerk; Don B. Chaffin
The strength constraints in a two-dimensional static human force exertion capability model (HFEC) have been evaluated using eight male and female subjects of varying anthropometry and strength capability. The model comprehensively estimates feasible exertion capability under symmetric conditions using a set of fifteen linear constraint equations from three constraint classes: strength, stability, and coefficient of friction (COF). This evaluation examines the nature of the limiting strength constraints. The computer model aided in designing tasks (combining posture with force exertion direction) that isolated upper extremity strength constraints and hip/torso strength constraints from stability and COF constraints. Subject performances of maximum exertions were recorded using force platforms and a multi-axis load cell to record external reaction forces at the hands and feet. Body posture was recorded with a 2D motion analysis system. The observed hand force exertions were compared to the exertions predicted by the model. The identity of the limiting constraints was well predicted by the model. The location of the constraints was logical and predictable. The results are discussed in the context of other modeling approaches as well as implications for future research. The HFEC approach shows excellent potential as an ergonomic engineering tool for teaching, evaluation, and design.

INDUSTRIAL ERGONOMICS: Panel

Ergonomics Efforts in the Retail Food Industry BIBA 744-748
  Thomas J. Sluchak; Douglas C. Antonelli; Pat Bower; Mark S. Hoffman; Gary B. Orr; Thomas R. Waters
This panel is composed of individuals from retail, ergonomic consulting firms, equipment manufacturers and NIOSH, who are currently involved with ergonomics efforts in the retail food industry. Presenters summarize their ergonomics efforts and discuss key challenges in the industry today.

INDUSTRIAL ERGONOMICS: Measurement

PVAT -- A Video Analysis Tool for Microgravity Posture Evaluation BIBA 749-753
  Mihriban Whitmore; Darlene Merced-Moore; Susan C. Adam
PVAT (Posture Video Analysis Tool) has been developed to meet the special needs of ergonomist and human factors analyst attempting to evaluate microgravity working posture from video footage. These specialists often have very little or no control over the video coverage. Moreover, the majority of Shuttle mission videos are not recorded for quantitative analysis. The purpose for developing PVAT is to provide a structured methodology in which these specialists could optimize the data collection technique. PVAT is specifically designed to document microgravity postures using videos of astronauts working in a space environment. The primary focus of PVAT is identifying the microgravity working postures and relating them to design issues in the workplace. This tool is currently an interactive software prototype written in Supercard. Users are provided with a set of input parameters such as: subject code, body orientation, targeted body part, camera view (given subject location), body movement, and rating level. A secondary set of inputs are also available which provides the ability to document extraneous behaviors or activities such as bending, reaching and interruptions. The tool allows for the input parameters to be customized as needed. Once the setup is defined, the user begins documenting the target posture and/or behaviors. The paper will discuss PVAT, its space applications and plans for its use.
A Hand Posture Measurement System for Evaluating Manual Tool Tasks BIBA 754-758
  Myung Hwan Yun
A measurement system of describing the loads in the hand during manual tool tasks is presented. The system consists of a network of force sensitive resistors and an angle transducer glove (Cyberglove, Virtual Technologies). Eighteen different cylindrical grip tasks for six subjects were studied using the developed measurement system. Fourteen flexion and abduction angles and the ten force data from ten locations of the hand was measured for the sixteen tool tasks. The results showed that the flexion angle for the five fingers decreased with increasing grip span. Grip force was mainly controlled by the opposing action of the thumb and the index finger. The contribution of the thumb and index finger force to the total grip force was greater when the grip size was increased. A regression approach to estimate the joint flexion angle based on the hand anthropometry and grip characteristics showed significant results. It was possible to use the data from the measurement system as an input to the calculation of the joint torques and moments in the finger joints. The simultaneous measurement system of the finger joint angles and finger forces was useful in collecting the information on the hand force postures during the duration of the task. The system was also useful in providing detailed input data for the biomechanical analysis of the hand.
Tracking Median Nerve Conduction as a Method of Early Detection of Carpal Tunnel Syndrome BIBA 759-763
  Steven L. Johnson; Bobby Evans
Cumulative trauma disorders in general, and carpal tunnel syndrome (CTS), in particular, have been an increasingly costly problem for both the afflicted individual and the company that employs that individual. This research involved a longitudinal study of cumulative trauma in six poultry processing plants. The primary objective of this research was to evaluate the potential of a procedure that tracks changes in motor median nerve latencies as a method of early detection of carpal tunnel syndrome. Although there was a statistically significant difference between the average latencies of the non-symptomatic group and the symptomatic group, the use of motor median nerve latencies for predictive diagnostic purposes is definitely questionable. There was no systematic shift in latencies observed as a function of the time that the person had been performing processing tasks which are generally considered to be associated with CTS. A second important result was that the incidence rate of objectively evaluated CTS appears to be far lower than that generally reported in both the popular media and the research literature. Probably the most important conclusion of the study, however, was that the variation within people, over time, independent of exposure, can lead to serious misdiagnosis of CTS. These results and conclusions are very important for both assessing the magnitude of the problem of CTS, as well as questioning the efficacy of one of the most widely used criteria to justify CTS surgery.
Feasibility of Using the Gap Detection Tactility Test for Monitoring Cutaneous Sensory Deficits BIBA 764-768
  One-Jang Jeng; Robert G. Radwin
Periodic worker monitoring methods are needed for detecting cumulative trauma disorders, such as carpal tunnel syndrome (CTS), in the early stages. An experiment was conducted for studying the feasibility of using a new aesthesiometer for periodically measuring functional tactile sensitivity. It was conducted to investigate gap detection sensory threshold differences between five normal subjects and seven subjects diagnosed having CTS. The gap detection test was used because of its functional resemblance to many work-related activities. Average gap detection sensory threshold using the index finger was 0.21 mm (SD = 0.14 mm) for the normal subjects and increased 114% to 0.45 mm (SD = 0.16 mm) for the CTS subjects when finger probing was allowed. Average gap detection sensory threshold using the index finger was 1.57 mm (SD = 0.56 mm) for the normal subjects and increased 61% to 2.53 mm (SD = 0.82 mm) for the CTS subjects when finger probing was not allowed. The results suggest that people suffering from CTS may experience similar functional deficits in daily living and work activities. A strong relationship was also observed between electrophysiologic variables and the gap detection sensory thresholds when both the CTS and normal hands were pooled. This suggests that performance in the gap detection test might measure the level of median nerve function in CTS.

INDUSTRIAL ERGONOMICS: Quantitative Applications

The Influence of Anti-Fatigue Mats on Back and Leg Fatigue BIBA 769-773
  C. Stuart-Buttle; W. S. Marras; J. Y. Kim
Prolonged standing is common in many industrial workplaces. It is also quite common for workers to complain of discomfort in the back and legs as a result of prolonged standing. Mats are often provided for the worker to relieve this fatigue. However, there is no quantitative evidence that these mats relieve leg and back fatigue. Five subjects were asked to stand on a concrete surface and two mat surfaces for prolonged periods of time. Spectral electromyo-graphic (EMG) analyses indicated that mats reduce localized muscle fatigue in the erector spinal muscle only. Furthermore, this fatigue reduction occurred only with the more compressible of the two mats tested. These results imply that localized muscular fatigue in the leg may not be relieved with "anti-fatigue" mats and some of these mats only benefit the back.
Case Study: An Application of the Revised NIOSH Lift Guide to a Multiple Task Job BIBA 774-778
  David B. Mahone
The newly revised NIOSH lifting guide offers a multiple task strategy for frequency weighting multiple lifting tasks performed in a series; in close proximity of time. This strategy allows calculation of a composite lifting index (CLI) during assessment of jobs for which lifting variables are changing throughout the task. While the approach is useful, the number of calculations and table look-up procedures required is much larger than a single task strategy requires, and the process becomes tedious and error prone if performed manually. Consequently, a computer program was developed by Continental Insurance Corporate Loss Control in FORTRAN to automate table look-ups and required calculations. A case-study applying the multi-task approach to an actual job is shown. The job involves manual lifting/lowering of boxes from a queuing turntable to a pallet stack. The results indicate that the job is unacceptably hazardous, which agrees with subjective responses of workers. Possible worksite retrofit changes are also evaluated in a "what-if" manner. These results show that changes would improve the risk level, but proposed improvements were not sufficient to attain an acceptable risk level. Mechanization of the job is therefore suggested. Details regarding the multi-task application are discussed.
The Effects of Posture and Technique on Forces Experienced when Hanging Continuous Miner Cable BIBA 779-783
  Sean Gallagher; Christopher A. Hamrick; Mark S. Redfern
Analysis of lost-time back injuries in underground coal mines indicates that handling continuous miner cable places workers at high risk of injury. Manual hanging of this type of cable is a common lifting task in underground mines. This study was performed to assess the ground reaction forces associated with hanging cable in various postures and employing different methods of securing the cable. Seven experienced coal miners (mean age: 41.4 years +/- 2.1) performed a series of 12 cable hanging tasks. Independent variables included a set of six posture/vertical space constraint conditions (LIFTCOND), and two techniques of securing the cable to the ceiling (METHOD). The dependent variables consisted of ground reaction forces measured using two force plates. LIFTCOND (F(5,66) = 21.31, p < 0.0001) and METHOD (F(1,66) = 10.89, p < 0.005) both significantly affected the magnitude of the peak resultant forces generated during the tasks. Post hoc analysis indicated that kneeling postures resulted in significantly lower forces than stooping for the same ceiling heights. Greater forces were associated with higher lifting conditions, attributable in part to the fact that higher lifts require more cable to be hoisted. Forces were also increased when subjects twisted baling wire to secure the cable, as compared to hanging it on a hook. An interaction between LIFTCOND and METHOD was identified with lateral shear forces -- stooping conditions where the subjects twisted the cable with wire resulted in higher lateral shear forces. Results of this study will be used to develop recommendations to reduce back injury risk when handling cable.
Ground Reaction Forces during Miner Cable Pulling Tasks BIBA 784-788
  Christopher A. Hamrick; Sean Gallagher; Mark S. Redfern
The handling of mining machine cables in underground coal mines has been identified as a particularly stressful task and is a likely contributor to low back pain. In this experiment, seven experienced miners performed a cable pulling task while ground reaction forces and cable tension were measured. The independent variables were two levels of cable resistance (low and high) and lifting conditions (kneeling under a 1.2 meter [48 inch] roof, stooping under a 1.2 meter [48 inch] roof, stooping under a 1.5 meter [60 inch] roof, and unrestricted standing). The dependent variables were the peak values of the following: actual tension measured in the cable, ground reaction forces in the X (anterior), Y (lateral), and Z (vertical) directions and the magnitude of the resultant force vector. Work posture significantly affected the peak ground reaction forces in the Y-direction. The Y-forces were highest in the kneeling condition, indicating that there is less postural stability when performing cable pulling tasks in a kneeling posture. Thus, there may be a greater likelihood of injury in this posture. Additionally, biomechanical stresses which contribute to musculoskeletal injury may be greater in the kneeling posture.

INDUSTRIAL ERGONOMICS: Cognitive Biomechanics

Can Biomechanically Determined Stress be Perceived? BIBA 789-792
  Deborah D. Thompson; Don B. Chaffin
Back and overexertion injuries are a costly and debilitating problem in industry. It has been suggested that the best protective action in the prevention of back injuries is to rely on a person's perception of the risks, and allow them to operate within them. However, this assumes that a person is aware of the sensory information from the body concerning unsafe levels of stress, particularly in the back. Unfortunately, there is some question as to whether this assumption is valid. The purpose of this study was to determine how well physical stress resulting from performing occasional lifting exertions could be perceived. This required an evaluation to determine how perception (psychophysical approach) relates to physical tolerances (biomechanical approach). The results showed that back stress resulting from occasional lifting exertions is not well perceived in general. The fact that the stress was not well perceived by some may indicate why low back injuries are so pervasive in the population, and why engineering and ergonomic changes are needed to reduce the exposure to conditions that would overstress the back.
The Performance of Female Young Adults in Perception of Efforts of Varied Nature and Magnitudes BIBA 793-797
  Shrawan Kumar; Maureen Simmonds; David Lechelt
Ten normal young adult females performed maximal and graded exertions of the stoop lift, hand grip, and finger pinch. The levels of graded exertion required were 80%, 60%, 40% and 20% of maximal voluntary contraction (MVC). The sequence of all conditions were fully randomized. Each of the randomized conditions was tried three times in succession. The entire experiment was carried out on four different days at the same time of the day on Monday, Wednesday, Friday of one week and Friday of the next week. The data obtained were subjected to descriptive and statistical analysis with t-test, analysis of variance, and correlation and regression. There were significant differences in the efforts produced in three different activities (p<0.01). The levels of exertion from 20% to 80% were significantly different from each other (p<0.01). However, there were no significant differences between the three trials of any given condition and the exertions produced on four different days. The 80% and 60% of exertions were overestimated and 20% was underestimated compared to the objective values based on MVC (p<0.01). At 40% effort there was no significant difference between the objective level of exertion and subjectively gauged and produced effort. The reliability of perception among the female subjects was similar for finger pinch, hand grip, and stoop lift activities.
The Effects of Obstructions on Arm Movement Time during Reach and Positioning Movements of a Simulated Maintenance Task BIBA 798-802
  Susan A. Taylor; Thomas Z. Strybel
The purpose of this study was to investigate the fundamental issue of how an obstruction affects movement time during reach and positioning components of a simulated maintenance task. Eight obstruction locations for two target locations provided the experimental manipulation for the study, while movement time was measured as the dependent variable. Data for all the trials were obtained using a three-dimensional magnetic sensing device placed on the back of the subject's hand as he/she moved in space from the starting point to the target in a wooden mockup replicating the work space of a maintainer in an aircraft horizontal stabilizer. Results indicated that movement times increased when the vertical position of the obstruction was within roughly 5.72 cm of the target. Subjects' perceived difficulty in those conditions with longer movement times was attributable more to the inability to see the target during the end of the motion than the lack of positioning space around the target. These findings emphasize the role visual feedback played in a task of this type, and its effect on maintenance procedure times in general.
Psychophysical Assessment of Simulated Assembly Line Work: Combinations of Transferring and Screw Driving Tasks BIBA 803-807
  Sheila Krawczyk; Thomas J. Armstrong; Stover H. Snook
Upper extremity cumulative trauma disorders have been linked to the repeated and/or forceful exertions and/or awkward postures sometimes required by upper extremity intensive work. The combined effect of these physical stressors can be evaluated using psychophysical methods. The purpose of this study was to examine different combinations of repetitive upper extremity work using established psychophysical methods to determine design recommendations for upper extremity tasks. The tasks studied simulated assembly line type work where a part is transferred from a storage bin and attached with a pneumatic tool to another larger part.
   Twenty-four experienced industrial workers performed five combination tasks of transferring an object along a conveyor and screw driving using a pistol shaped pneumatic screwdriver: 100% transfer; 75% transfer and 25% screw drive; 50% transfer and 50% screw drive; 25% transfer and 75% screw drive; and 100% screw drive. The cycle time was 24 seconds. Each combination task was performed for an hour. Overall, transferring, and screw driving perceived exertions were measured using 10 cm visual analog scales (VAS) with verbal descriptions at the endpoints. The left and right sides corresponded to "Easiest imaginable work" at 0 cm, and "Hardest imaginable work" at 10 cm, respectively. Body part discomfort surveys were utilized to assess discomfort from each of the tasks.
   The overall perceived exertion (VAS) rating increased, as the task utilized more of one upper extremity than the other and involved more of either the transferring or screw driving tasks. The mean overall VAS ratings were 5.3, 4.3, 3.5, 4.4, and 5.3 for the five combination tasks, respectively. As the transferring (or screw driving) proportion of the task increased, the transferring (or screw driving) VAS increased. A repeated measures ANOVA showed that the combination task effect was significant (p<0.01). This psychophysical data can provide guidance in the analysis and design of upper extremity work. Since less varied work which utilized more of one upper extremity than the other had greater overall perceived exertion, upper extremity tasks should be designed as varied as possible utilizing as many body parts as possible. Body part discomfort surveys verified that this decreased discomfort severity and distributed the discomfort more evenly throughout the different body parts. This study provides evidence of the positive effects of work enlargement.

INDUSTRIAL ERGONOMICS: Application Research

Validation of Ergonomic Improvements to a Shipping Workstation BIBA 808-811
  John L. Wick; Rick DeWeese
A shipping workstation was analyzed by doing detailed task analysis from video tape. The analysis showed an excessive number of damaging wrist motions left and right, high force pinch grips left and right, extreme right shoulder abduction, extreme neck flexion and extreme back flexion. Solutions were developed to address the causes. The new design was validated. It was found that it eliminated the high force pinch grips, extreme shoulder abduction and extreme back flexion as well as reducing cycle time by 12%. However, it failed to solve the excessive number of damaging wrist motions and extreme neck flexion and introduced extreme shoulder flexion. New solutions were developed. The next validation proved successful. This study demonstrates the importance of a methodology that includes a validation step. Without validation, the new workstation would not have been much better than the old one.
Ergonomic Improvements in a Medical Device Assembly Plant: A Field Study BIBA 812-816
  Mukund Narayan; Linda Rudolph
This study reports the results of an ergonomics demonstration project implemented at a medical device manufacturing plant that was concerned about the high incidence of upper extremity cumulative trauma disorders (UECTD). Plant records were reviewed to target high risk jobs for intervention and to establish baseline incidence and severity rates for future comparisons. A multi-disciplinary team based approach was to used identify problems and effect workplace changes. With the guidance of the ergonomist, the team conducted task analysis of selected high risk operations, developed solutions, validated them for feasibility and cost-effectiveness on a prototype workstation, and, after implementing the changes on the production line, measured the effectiveness of the changes. The plant-wide severity rate based on lost-time was reduced from 154.9 to 67.8 lost-time days per 200,000 worker-hours over a one-year period. The incidence and severity rates were reduced significantly for the redesigned jobs.
An Evaluation of Workstation Adjustment and Musculoskeletal Discomfort BIBA 817-821
  Craig A. Halpern; Paul J. Davis
Ninety (90) office workers were administered a survey to gather a subjective evaluation of appearance, layout, useability and efficiency of their workstations, and to develop a body part discomfort rating. All ninety workstations were then reconfigured and adjusted to fit each user's anthropometric dimensions. After approximately four months, a follow-up survey was conducted. Results from the reconfiguration and "fitting process" indicated a significant decrease in body part discomfort, and an increase in the perceived efficiency, and useability of the office furniture and equipment. Use of office equipment properly adjusted to fit the user through ergonomics and anthropometric principles may enhance productivity and performance, reduce awkward postures, and the associated cumulative trauma injuries.
The Ergonomic Evaluation and Improvement of a Cable Forming Process: A Case Study BIBA 822-825
  Kelly A. Eckbreth
Since 1986, twelve (12) injuries and illnesses had occurred among cable formers in several shops of a major telecommunications equipment manufacturer resulting in significant lost time and restricted days. The process engineer, supervisor, plant ergonomist, production associates, and maintenance personnel analyzed the problem elements of the job and developed possible solutions. Ergonomic training, repair of the existing boards, a new cable board design, anti-fatigue mats, step stools, and new scissors were implemented. Significant improvements were realized in employee morale and board set-up time. The degree of musculoskeletal stress suffered by these workers was also reduced.

INDUSTRIAL ERGONOMICS: Industrial Ergonomics Potpourri

The Effects of Extra Vehicular Activity (EVA) Gloves on Dexterity and Tactility BIBA 826-830
  Ram R. Bishu; Glenn Klute; Byungjoon Kim
Human capabilities such as dexterity, manipulability, and tactile perception are unique and render the hand as a very versatile, effective and a multipurpose tool. This is especially true for unknown microgravity environments such as the EVA environment. Facilitation of these activities, with simultaneous protection from the cruel EVA environment are the two, often conflicting, objectives of glove design. The objective of this study was to assess the effects of EVA gloves at different pressures on human hand capabilities. A factorial experiment was performed in which three types of EVA gloves were tested at five pressure differentials. The independent variables tested in this experiment were gender, glove type, pressure differential, and glove make. Six subjects participated in an experiment where a number of dexterity measures, namely time to tie a rope, and the time to assemble a nut and bolt were recorded. Tactility was measured through a two point discrimination test. The results indicate that a) With EVA gloves there is a considerable reduction in dexterity, b) performance decrements increase with increasing pressure differential, and c) some interesting gender glove interactions were observed, some of which may have been due to the extent (or lack of) fit of the glove to the hand. The implications for the designer are discussed.
Development of a Pressure-Related Assessment Model of Seating Discomfort BIBA 831-835
  Wenqi Shen; Ian A. R. Galer
This study consisted of the development of a factor model and a sitting interface pressure related assessment model of sitting discomfort, based on an extensive literature review. The factor model identified the force applied on the sitter's body as one of the main factors causing seating discomfort. The assessment model proposed that sitting discomfort mainly arises from feelings in the lumbar and buttock areas, and that local discomfort either depends upon or, is reflected by, the interface pressure. A pilot experiment was conducted to explore the utility of the assessment model by change of postural angles. Eleven subjects attended a 40 min sitting session. The independent variables were seat angle and seat-to-backrest angle. A pressure measuring device was used to record interface pressure between the subject and a prototype seat surface. A general comfort scale was administered after each pressure measurement. Results showed that all pressure measures were sensitive to postural changes of varied angulation, and that subjective ratings of comfort correlated with pressure measures, especially maximum pressure, average pressure ratio and maximum pressure gradient. Evidence from the pilot suggested that the model may have utility and eventually be used to assess seating discomfort.
Development of an Object-Oriented Anthropometric Database for an Ergonomic Man Model BIBA 836-840
  Eui S. Jung; Dongsoek Kang; Sung H. Han; Min K. Chung
An object-oriented anthropometric database was developed as a framework of integrating into an ergonomic interface model, data for workplace modelling, and ergonomic evaluation functions as well as basic anthropometric data required to construct a man model. In order to develop an ergonomic man model representing operators that interact with their working environments, not only anthropometric data but also efficient handling of such data and accurate representation of the workspace are needed as a prerequisite to proper ergonomic evaluation. In this research, these three sets of data with distinct characteristics were incorporated into a common integrated database needed for the manipulation of an ergonomic man model together with the generation of an anthropometric man itself. An object-oriented database scheme was used for designing the database to achieve flexibility and expandability, and to efficiently interface to any CAD system. UniSQL/X, an object-oriented database management system and the X-window system on a SPARC workstation were used for implementation. The ergonomic man model generated from the object-oriented database is found to possess great flexibility and performance compared with existing ergonomic interface models or ergonomic CAD systems.
What Difference Can the Data Make? BIBA 841-845
  H. A. Romero; L. T. Ostrom; C. A. Wilhelmsen
The anthropometric data which is readily available to the ergonomic practitioner contains gaps in the statures of individuals covered. This study fills in those gaps by analyzing the data sources available to interpolate the dimensions for those statures not represented. The interpolation method used was linear regression relating a specific dimension to the standing stature of the individual. Additionally, this paper compares several sources of data to demonstrate significant differences. Both these pieces of information are important to the practitioner. By filling in the gaps, the practitioner is provided with initial quantitative reference points for individuals when properly arranging a workstation. Currently, only qualitative information is provided concerning optimum workstation design for individuals not represented in the data sources. By demonstrating the lack of a significant difference between data sources, the practitioner may use whichever source is readily available. The results show a significant relationship between the individual's stature and eight different workstation measurements. Finally, there is no significant difference between the data sources examined.

MEDICAL SYSTEMS AND FUNCTIONALLY IMPAIRED POPULATIONS: Human Factors in Health Care and Universal Design

Human Error in Health Care Delivery: Cases, Causes and Correction BIBA 846-848
  Harold P. Van Cott
Health care delivery is viewed as a complex, people-intensive system whose reliability depends on human performance. Examples of the human errors that occur in health care are described, and human factors interventions and remedies that might be taken to improve reliability and safety are suggested.
Development of Tactile Displays for Blind Access to Computers BIB --
  Steven F. Wiker; Gregg C. Vanderheiden; Seongil Lee
The Effects of Physical Attributes of Computer Interface Design on Novice and Experienced Performance of Users with Physical Disabilities BIBA 849-853
  Sherry Perdue Casali; Joseph D. Chase
It is well accepted that with even very simple tasks, a user's performance with a cursor control device improves substantially over some period of time before stabilizing. Although no systematic studies are available concerning how particular attributes of screen or device design affect the rate at which users learn to interact with a system, past studies with input devices have shown that the overall period of time required to learn to physically interact with a system is generally quite short. Hence the lack of attention paid to the "learning" phase with respect to physical interaction is probably justified. For users with mobility impairments, however, not only may the overall physical learning phase be significantly longer than for nondisabled users, but certain features of the interface design may require a longer learning period than others. Depending on how different "initial" performance is from "practiced" performance, systems meant for "walk up and use" or casual use may need to be designed differently to allow easy access for persons with mobility impairments. In addition, adaptive interfaces which change the physical design of features over time as a user becomes more proficient may facilitate access for individuals with impaired motor control.
   Twenty persons with impaired hand and arm function (as a result of spinal cord injury) performed a target acquisition task with five cursor control devices. The task required that the user select targets of different sizes and distances using both "point and click" and "drag" modes of interaction. Time and errors were recorded. The results indicate not only that some physical design attributes negatively effect performance, but that the magnitude of the effects differ for "initial" performance and "practiced" performance. In fact, in some cases attributes which had no effect once performance had asymptoted were shown to have a significant effect on novice performance. Also, some features required significantly longer periods of time for the users to become proficient at using than others. The implications for interface design are discussed.
Developing the User-System Interface for a Communications System for ALS Patients and Others with Severe Neurological Impairments BIBA 854-858
  Robert A. Murphy; Annamaria Basili
In developing a computerized communications system for the severely neurologically handicapped, the user-system interface required adaptation to the special limitations of this population. The needs of health care workers, who assist the patient in the use of Blink-writer, were also addressed as part of the system design.

MEDICAL SYSTEMS AND FUNCTIONALLY IMPAIRED POPULATIONS: Panel

Risk Assessment and Approaches to Addressing Human Error in Medical Uses of Radioisotopes BIBA 859-862
  Isabelle Schoenfeld; Dolores Morisseau; James R. Callan; Kerm Henriksen; Edwin D. Jones; Ronald D. Kaye; Michael L. Quinn
The objective of this panel is to provide a forum for the presentation of the results of the human factors analyses of two discrete medical systems (Teletherapy and Remote Afterloading Brachytherapy) and the risk assessment of a third (Gamma Knife). Although each of these systems uses some form of radiation to effect patient treatment, each is unique in the method used to effect the treatment.
   Records maintained by the Nuclear Regulatory Commission (NRC) indicate that human error is a primary or contributing factor to misadministration of prescribed doses of radiation during medical treatment. Such misadministrations, whether by machine or human error can have adverse consequences. Hence, the NRC undertook human factors analyses of the teletherapy and the remote afterloading brachytherapy systems and a risk assessment of the use of the gamma knife to determine the root causes of human errors and their potential risks.
   Results of these analyses will be discussed and include identification of the factors that contribute to human error in these systems, the impact of those factors on the performance of functions and tasks, their safety significance, and alternative approaches for resolving the safety significant human factors problems (e.g., improvements in human-machine interfaces, task design, procedures, training, and organizational practices). The risk analysis was designed to include a task based approach that departs from conventional probabilistic risk assessment techniques and provides risk profiles that can identify relatively high-risk or critical tasks.
   Hence, this panel will provide the human factors community with insights into techniques and results of human factors analyses and risk assessment performed on medical systems heretofore unexamined in this depth or across such a broad range of considerations.
Human Factors and Medical Care: Issues and Examples BIB --
  Marilyn Sue Bogner; Melvin H. Rudov; Roberta Klatzky; Lee T. Ostrom; William A. Hyman; John W. Senders

ORGANIZATIONAL DESIGN AND MANAGEMENT: Panel

Making Human Factors Usable BIBA 863-866
  Susan Dray; Tom Dayton; Deb Mrazek; Frederick A. Muckler; Mike Rafield
Over the years, Human Factors as a discipline has matured, and evolved. This panel brings together a variety of participants who represent various aspects of the Human Factors community. It is the position of the participants that boundaries still exist between Human Factors professionals and the "users" they profess to assist.
   These boundaries take a variety of forms, including organizational, philosophical, and linguistic (i.e., the jargon of the Human Factors profession, and the jargon of their "users"). We believe that bridges must be built to span these boundaries, bringing together the Human Factors community and their customers -- in effect, making Human Factors usable.
Team Training, Group Processes, and Organizational Psychology: Major Theoretical and Research Issues that Bridge Boundaries BIBA 867-869
  Richard E. Christ; Alvah C. Bittner; Allen T. Bramwell; Eduardo Salas; Winfred, Jr. Arthur; Richard A. Guzzo; Joseph W. Huff; Michelle M. Robertson
As is generally true for most people during their normal day-to-day existence, there is a tendency for researchers and practitioners who deal with behavioral and social issues to communicate predominately with those who share with them a common frame of reference in matters of professional significance. For example, if the issue at hand is the behavior of people in relatively small groups -- groups with highly specific goals, instrumental relationships, and no necessity for permanence -- there are clearly at least two clusters of individuals interested in the issue. Individuals within each cluster have a common frame of reference and communicate among themselves information concerning their attempts to acquire and apply knowledge about the behaviors of people in groups as well as the behavior of the groups themselves. These two clusters of individuals are often differentiated by their respective associations with (a) team training and performance, typically in a military or aviation context, and (b) group processes and productivity, typically in an industrial or organizational context.
   It can be easily shown that there is a high level of activity within and meaningful output from each of these two clusters of researchers and practitioners. The problem is that there is the ever present danger that individuals within each of these two clusters will not be sufficiently aware of and hence not be able to benefit from the activities and products of the other. In short, the situation as described minimizes the opportunity for a positive synergism among those who really share a larger set of common interest and goals.
   The objective of this panel is to provide a forum for discussion of issues that are part of the larger set of common interests and goals. The panelists are individuals who might be identified as representing principally only one of the two clusters of researchers and practitioners. Each one, however, probably prefers to be and is in fact recognized as a major contributor by members of the other cluster. The desired impact of the brief presentations by the panelists, together with subsequent interactions among the panelists and others in the audience, is to facilitate a recognition and appreciation of the total set of contributions being made in the area of team, group, and organizational research and practice.
Performance Enhancement and Accident Reduction in Complex Systems: Perspectives and a Research Program BIBA 870-872
  Barrett S. Caldwell; Bruce G. Coury; Najmedin Meshkati; Neville Moray; Harold E. (Smoke) Price
Accidents in complex systems seldom arise from a single source, and are most often the result of multiple factors occurring at different levels of the system. Understanding the "systems" aspects of human performance (and performance error) in complex systems is a necessary part of any effort to avoid serious mishaps due to human error. This panel is intended to coincide with the development of a major research effort at the University of Wisconsin to address these issues. The Center for Human Performance in Complex Systems will apply the disciplines of systems engineering and ergonomics design to improve complex systems processes from the perspective of human performance. The purpose of this panel is to foster and demonstrate the Center's interest in bringing together a variety of perspectives and expertise bases to improve the overall quality and breadth of its activities. Each of the participants has a long-standing interest in improving the quality of human performance in complex and critical systems environments. Although they cannot represent the entire spectrum of relevant disciplines and perspectives of ergonomics and systems analysis, they provide a balance of insights, experience, and enthusiasm. This balance is essential to improving our understanding of factors affecting complex socio-technical systems, and implementing strategies to prevent and ameliorate the effects of system degradation and breakdown.

ORGANIZATIONAL DESIGN AND MANAGEMENT: A Macroergonomics Toolbox

Diagnosing Macroergonomic Problems: A Case Study in the Use of Concept Mapping for TQM Initiatives BIBA 873-876
  Brian S. Zaff; Edward R. Hughes; Michael D. McNeese; Clifford E. Brown; Maryalice Citera
This paper presents the results from a case study involving the use of concept mapping in a Total Quality Management (TQM) program. Concept mapping is a knowledge acquisition technique that has proven successful in a variety of instances when it was necessary to elicit information directly from domain experts and communicate that information to other individuals needing the information. The concept mapping technique produces, during the course of an interview, a graphical representation that becomes a communications medium through which ideas can be easily shared in a group setting. In TQM programs it may be necessary to elicit detailed information from employees about the nature of their work domain and about the various problems they may be encountering. The success of TQM programs often depends on establishing open lines of communications through which employees can articulate their concerns and upon the ability of TQM team members to uncover hard-to-detect problems. Concept mapping proved successful in the TQM setting. The concept mapping technique facilitated the uncovering of insights that were not obvious to the TQM team during their initial brainstorming sessions or from the use of a survey. In addition it appears that the concept mapping technique has other significant TQM advantages over and above its utility as a knowledge elicitation technique. Concept mapping, not only facilitates user-centered knowledge acquisition, but also appears useful as a means of facilitating team-building.
Note: Paper ends on page 881
Macroergonomics Research Methodology: Determining Future Job Requirements of a Customer Service Representative (CSR) in a Bank BIBA 877-880
  Mark S. Hoffman; Cynthia K. Lowe; Karen S. Wilson
Macroergonomic research techniques were used to determine current and future organizational changes, information technology requirements, and personnel training and recruiting demands for Customer Service Representatives (CSRs) in a bank. This research demonstrated the power of suite of behavioral science methods that included: group interviews, task analysis, focus groups, and concept mapping. Concept mapping proved to be an effective method for illustrating differences in group perceptions; five clusters were mapped for both CSRs and managers. Responses differed significantly among four of the clusters. The sequence used in the application of these methods was critical to maximize the value and validity of the results. The results from this study are useful for identifying the challenges that the retail banking industry has to address in order to change the role of the CSR to meet anticipated future business demands.
Growing a Styleguide: Macroergonomic Strategies for Achieving Consistent User Interface Design BIBA 882-885
  Robert W. Root
Consistency in user interface design is generally recognized as a desirable goal. The main problem facing most practitioners is how to achieve it. In many cases the solution begins with a user interface styleguide that defines the design criteria for user interface developers. A styleguide is a necessary, but not sufficient, part of the solution. In practice, achieving consistency requires a multi-faceted approach ranging from design guidelines to organizational structures and processes. This paper discusses macroergonomic aspects of styleguide development in a large software development organization, focusing on the processes and organizational strategies used to develop content and achieve initial buyin by user interface designers and developers.
The Resurrection of Span of Control BIBA 886-890
  Brenda M. Wenzel; Richard E. Christ
Operating environments have been undergoing unique changes that are causing management to reexamine factors that impact organization design. In attempting to respond to this design challenge, it became clear that there is a need for high quality empirical research directed at the organizational concept of span of control (SOC). The concept of SOC refers to the number of subordinates that one leader can effectively command and control. The purpose of this research paper is to summarize the outcome of a comprehensive analysis of the literature relevant to SOC and to discuss research issues on this topic. Six interrelated factors emerged from the literature review as important in determining a leader's proper SOC. The critical factors are tradition, environmental uncertainty, level of technology, subordinate's task characteristics, leadership behavior, and leader's workload. A research program is being developed to investigate these six factors with the goal of establishing a theoretical groundwork for the concept of SOC. Additionally, democratization as a design principle is introduced as an innovative approach to organization design.

ORGANIZATIONAL DESIGN AND MANAGEMENT: Macroergonomics Perspectives on the Same Old Safety Problems

The Integration of Ergonomics in a Safety Improvement Program: Design and Implementation of an Ergonomics Initiative BIBA 891-895
  Robert L. Getty
When safety performance is characterized by high levels of strains, sprains and cumulative trauma injuries the need for ergonomics is clearly indicated. In addition, when workmanship defects and worker compensation costs are at an unacceptable rate the need for accelerated action is evident. When there is limited ergonomics orientation in a particular company, ergonomics cannot be prescribed as a cure-all. The program must enhance overall company safety, quality and productivity objectives. This paper describes an ergonomics-oriented safety improvement program based on these conditions, a benchmarking effort and the review of Human Factors Society proceedings and other ergonomics literature. The highlights of the program are participatory ergonomics, in-house ergonomic expertise development and integration with other company goals, medical management and other safety programs. Since the company size is much larger than most company programs and the need for accelerated improvement is required, a quick-fix initiation is recommended. This is accompanied by a development of long range medical management and prevention procedures. The initial phases of the program are underway and have been met with enthusiasm and an attitude that this involvement approach makes good sense. It is anticipated that the description of the development and initiation of this ergonomic program will provide beneficial interchange of professional experiences.
Process Safety Management System Performance Measures for the Chemical Industry BIBA 896-900
  Edward Connelly
The Center for Chemical Process Safety of the American Institute of Chemical Engineers has developed a twelve-element model management system for process safety. Concord has worked with CCPS to develop performance measures for two of the elements, namely "Management of Change" and "Training". A unique feature of the measures is that they continuously assess the performance of the elements, a feature somewhat analogous to the control of a plant. This contrasts with an audit evaluation which captures a snapshot of the management system performance at a particular instant of time.
   Of special interest here is the method used to build the measures which employed chemical plant process safety experts performing the functions for which they are accepted as experts. For instance, analysis of the management systems used a method well known to chemical engineers for assessing chemical process safety, the Hazard and Operability Study (HAZOP) (AIChE/CCPS 1985) process. Further, synthesis of the performance measures employed process safety experts in a role they perform in their professions -- assessment of the level of performance of various demonstrations of process safety management systems. This methodology is believed to be a reliable way of obtaining information from experts. That method is described in this paper.
Physical and Psychological Factors in Perceived Safety: A Macroergonomic Case Study BIBA 901-904
  Andrew S. Imada; Roy J. Hubert
This paper describes on-going efforts to reduce real and perceived safety risks in a large newspaper publisher. These risks have been traditionally treated by analysis and remediation of physical conditions exclusively. This case illustrates how psychological and organizational factors can alter perceptions of unsafe conditions. Organizational culture, attitudes and affective states appear to influence perceptions of risk and harm. A macroergonomic analysis and participatory approach have been effective in reducing complaints and costs to date.
A Compensatory Rest Break System for VDT Operators BIBA 905-909
  Robert A. Henning; George V. Kissel; Douglas C. Maynard
Short rest breaks at 10 or 15-min intervals are being proposed as a means to moderate health problems and discomfort associated with continuous VDT use. This laboratory study evaluated an alternative to administering frequent breaks on a regimented schedule; short breaks were not administered unless the operator's spontaneous rest pauses were insufficient. Undergraduate volunteer typists (N=38) were assigned to one of two conditions: regimented (20-sec breaks every 5 min), or compensatory (20-sec breaks every 5 min only if the spontaneous pauses did not total 20 sac). Participants entered lines of randomized upper and lower-case characters that appeared on their VDT during a 48-min work period. Mood and musculoskeletal discomfort were assessed before and after the work period, followed by a questionnaire about the break system. Performance measures included keystroke output, error rate, and correction rate (backspace use). Large pre-to-post work period differences in both mood and musculoskeletal discomfort were found. Both the number and length of computer-administered breaks decreased in the compensatory condition. Back discomfort was lower in the compensatory condition, however, no differences in performance, mood, nor acceptance of the break system were found. These results indicate that rest breaks administered on a compensatory basis during repetitive computer work can eliminate unnecessary breaks and improve well-being without being any more disruptive to work than regimented breaks.

PERSONALITY AND INDIVIDUAL DIFFERENCES IN HUMAN PERFORMANCE: Individual Differences in Personality and Human Performance

The Influence of Personality in the Processing of Display Formats BIBA 910-914
  John H., Jr. Kelleher; Bruce G. Coury
The importance of personality characteristics in the processing of displays is examined. Forty-six people, screened for specific information processing and decision making preferences using the MBTI, learned to classify instances of system data into one of four state categories. System data were presented in one of three types of display formats: a polygon; a barograph; and a digital display. The experiment involved two sessions: a training session where each person learned the classification task; and an extended practice session with no feedback. The ability of people to accurately classify instances was found to be influenced by both the type of display and their personality type. The importance of individual differences in display research is discussed, with emphasis placed on the implications for training, and selection of display formats.
Expert and Novice Differences in Recognizing Similar Situations BIBA 915-919
  Pat-Anthony Federico
To test hypotheses regarding expert and novice differences in recognizing similar scenarios, 28 senior naval officers and 52 junior naval officers (1) classified tactical situations each of which appeared on a note card, (2) labeled every created cluster to convey a category description, and (3) signified their criteria for sorting scenarios. Principal-components and discriminant analyses, and associated statistics, established that when categorizing situations (1) experts are more context-dependent than novices, (2) experts and novices do not differ significantly in the number of schemes and scenarios per schema formed as well as in the access avenues ascribed for these schemes, (3) experts do not process scenarios at significantly deeper levels of analysis than novices, and (4) experts do not assign significantly more importance to conceptual aspects or deep structures than novices, and less importance to perceptual properties or surface features than novices.
The "Right Stuff": Personality Tests and the Five-Factor Model in Landing Craft Air Cushion Crew Training BIBA 920-924
  David R., Jr. Street; Kathleen T. Helton
The purpose of our investigation was to determine if personality testing and a five-factor model could improve the selection of Landing Craft Air Cushion (LCAC) vehicle operators. Vehicle operators for the LCAC are currently selected on the basis of their performance on a computer-based psychomotor selection system. The various psychomotor tests in the selection system have demonstrated predictive validity in LCAC crew training. Certain personality characteristics may also be involved in the LCAC vehicle operator training success. In fact, various researchers have found that personality testing may improve the selection of Navy/Marine Corps aviators. There is increasing evidence that a five-factor model may be useful in describing the personality characteristics involved in training success. We believe that a five-factor model may improve the selection system used for LCAC vehicle operators. A principal component analysis with varimax rotation was conducted to determine the underlying structure of the Adult Personality Inventory (API) with 168 LCAC crew candidates. The resulting factor scores were then entered into a series of hierarchical multiple regression analyses to determine the relation of the personality factor scores and the performance-based test to an underway grade in training criterion. The results indicated that one personality factor, openness, significantly improved predictions of the criterion (p < 0.05). Based on these results, we believe that personality testing may improve the selection of LCAC vehicle operators.
The Preferences Scale: Multinational Assessment of a New Measure of Morningness BIBA 925-929
  Carlla S. Smith; Simon Folkard; Robert A. Schmieder; Luis F. Parra; Evelien Spelten; Helena Almirall
Several self-report scales have been developed to measure morningness, or the preference for early morning or late evening activity (i.e., larks vs. owls). This individual difference in human circadian (time-of-day) rhythms has applications in the selection and placement of shiftworkers for night work in industry.
   Researchers have recently questioned the suitability of existing scales for people with alternate sleep-wake schedules and lifestyles. These factors may also render existing scales inappropriate for use in some cultures. To address this deficiency, we developed a new morningness scale (the preferences scale) that is not yoked to specific times of the 24-hour day and has a simplified response format.
   Data on the preferences scale were collected from university students (total N=1,212) in four countries (U.S., England, Holland, and Spain). Responses on external validity measures (self-rated alertness over the waking day and actual and preferred arise and bed times) and another morningness scale (for comparative purposes) were also collected. Although scale statistics (aggregate and by country) suggest that the psychometric properties of the preferences scale were adequate, scale mean differences existed across countries. These results may indicate cultural, as well as the established biological, differences in morningness. However, a more thorough psychometric assessment is needed to substantiate this possibility.

PERSONALITY AND INDIVIDUAL DIFFERENCES IN HUMAN PERFORMANCE: Panel

Individual Differences in Technology Stress BIBA 930-934
  Janet J. Turnage; Bonnie J. Walker; Linda J. Kirk; Jennifer L. Greenis; Jennifer L. Dyck; Janan Al-Awar Smither
Two years ago, we convened a panel discussion at the Annual Meeting of the Human Factors Society (Turnage & Howell, 1991) to examine the possible negative effects of advanced computerized technologies. The session, titled "Technostress: Fad, Fallacy, or Fact?", explored whether or not the concept of technostress could be sufficiently well-defined and operationalized to lend itself to scientific scrutiny. The consensus of those in attendance was that the concept of technostress does deserve further research attention, particularly by human factors specialists who can offer a unique perspective to an area which heretofore has been treated from clinical and organizational psychology perspectives.
   Recognizing that the main goal in studying the phenomenon is to develop interventions to ameliorate technology stress through understanding the interrelationships among individual, organizational, and human-computer components, Turnage (1992) proposed an integrative model of technology stress. The model, like many other models of job stress, depicts technology stress as a multi-determined, multi-symptomatic construct that is composed of objective and subjective stressors which lead through various decision processes to stress responses. Stress responses are largely shaped by both individual and situational moderators and are translated by performance processes into individual and organizational consequences. Intervention strategies may be directed toward alleviating the stressors themselves, various components of the stress response, or symptomatic consequences of the stress response.

SAFETY: Warnings and Compliance

The Effectiveness of an Interactive Warning in a Realistic Product-Use Situation BIBA 935-939
  Richard R. Duffy; Michael J. Kalsher; Michael S. Wogalter
Warning labels are widely used to convey information about the safe use of products. In an attempt to design better warnings, researchers are exploring factors that influence their effectiveness. One design factor that appears promising is an interactive label that requires manipulation by the consumer using the product. In the present research, the effectiveness of two interactive warning labels (with and without a color component) were compared to a standard label in the context of a realistic product-use task. Additionally, task load was manipulated (low vs. higher). The results showed that the interactive labels were noticed, recalled and complied to more often than the standard on-product label. No effect of increasing task load and adding color to the interactive label was observed. The results indicate that the interactive label is a viable means of facilitating warning effectiveness.
The Impact of Color on Warnings Research BIBA 940-944
  Paul B. Kline; Curt C. Braun; Nancy Peterson; N. Clayton Silver
Researchers have examined a variety of attributes that influence a warning's ability to communicate important product hazards. These attributes include font type, signal words, and the use of icons. One attribute that has been noticeably absent from the warnings literature is color. Therefore, the purpose of the present study was to determine the appropriateness of achromatic stimuli in product warning research. Thirty-three undergraduate students rated color and achromatic versions of twelve labels. These labels varied across four levels of product class and three levels of signal word. All labels were evaluated on six attributes: salience, readability, hazardousness, likelihood of injury, carefulness, and familiarity. A composite variable called "perceived hazard" was formed from the averaged ratings of hazardousness, carefulness, and likelihood of injury. Moreover, an additional variable "perceived readability" was composed of the mean ratings of readability and saliency. Results showed that color labels were perceived as more readable and hazardous than achromatic labels. Implications for warning research are discussed.
Compliance with Warnings in High Risk Recreational Activities: Skiing and Scuba BIBA 945-949
  Alison G. Vredenburgh; H. Harvey Cohen
Warnings research generally has focused on identifying which factors influence people to read and remember the content of warnings. Additional research has determined that people tend to read warnings if they perceive an activity or product to be dangerous or if they are less familiar with it. However, for practical purposes, reading the label or warning does not go far enough. In addition to examining whether warnings have been read, the current study also addresses user compliance by surveying people immediately after they have completed a high risk recreational activity (either skiing or scuba diving). The three areas examined in this study were whether the perception of danger affected the reading of, and compliance with warnings; whether familiarity with an activity affected reading and compliance; and whether there was any difference in responses between men and women. As expected, the perception of danger and familiarity with the activity increased the reading of and reported compliance with warnings. Many differences were found between the responses of men and women. Although there was no sex difference in whether subjects read warnings, women reported complying with the warnings significantly more than men. In accordance with stereotypes, men were more likely to participate in high-risk sports; claim to have a higher ability in the activity; and participated in the activity more often than the women (in the two years prior to this study).
Behavioral Compliance with Personalized Warning Signs and the Role of Perceived Relevance BIBA 950-954
  Michael S. Wogalter; Bernadette M. Racicot; Michael J. Kalsher; S. Noel Simpson
Recent research has shown that compliance to a posted warning sign is much lower than the same warning located within a set of task instructions, even when the sign is highly visible. One possible reason for this finding is that participants' believe the sign to be less relevant to the task and to themselves than the within-instructions warning. One purpose of the present research was to examine whether a personalized sign (with the participant's name) is more effective than a more conventional impersonal sign (with the signal word CAUTION). A second purpose was to examine the influence of a dynamic display compared to a static display. A sign composed of programmable light-emitting diodes (LEDs) presented the warning message using special effects (apparent motion) or it was displayed continuously. A third purpose was to examine whether various sign placements in a cluttered laboratory environment influences compliance. The wearing of protective equipment by participants as directed by the warning was the measure of behavioral compliance in a chemistry laboratory task. More participants wore the protective equipment when a warning was present than when it was absent. The personalized sign increased compliance compared to the impersonal sign. No effect of dynamic presentation was found, and the only effect among sign placements was found for perceived accuracy. The effect of personalization is explained in terms of the special alerting feature of one's own name and increased perceived relevance that results when the message is directed to them. Implications for flexible control of personalized warning messages using available technology are discussed.

SAFETY: Contemporary Safety Issues in Driving

The High-Mounted Brake Lamp: A Cause Without a Theory BIBA 955-959
  Rudolf G. Mortimer
Studies are described that formed the basis for the Federal high mounted brake light standard and some that have been done since. One purpose of this paper is to show how some details of the new Standard are hard to derive based on the underlying research. In addition, there was no adequate theory of driver performance upon which the standard was based. Although experimental field studies forecast reductions in rear-end crashes of about 50%, analyses of actual reductions in rear-end crashes since the standard took effect estimated them to be 22% to 3.5%.
Age Differences in the Useful Field of View in a Part-Task Driving Simulator BIBA 960-963
  Jonathan Walker; Catherine Sedney; Kathryn Wochinger; Deborah A. Boehm-Davis; William A. Perez
This study investigated age-related differences in the useful field of view (UFOV) using a part-task driving simulator. Thirty-six licensed drivers, aged 20-25, 40-45, and 65-70, participated. Dynamic roadway images were projected on screens to the front and sides of the driver. Target stimuli consisted of full-size simplified images of a van moving forward on the side screens at a speed below the motion threshold. Subjects performed forward view tracking and cognitive tasks while responding to the van stimuli on the side screens. Increased levels of the forward view task load adversely affected response times to the vans for the older group only, but performance of the tracking task declined for all age groups with increased load.
Diagnosis of Alcohol Intoxication: Effectiveness of Cognitive and Neurovestibular Field Sobriety Tests BIBA 964-968
  Robert S. Kennedy; Janet J. Turnage; William P. Dunlap
Tests from an automated performance test battery of cognitive tests and the standardized field sobriety tests (FST) used nationwide by law enforcement officers were administered in three experiments involving graded dosages of alcohol. In the first experiment, subjects were raised to one of four levels of alcohol dosage in four different sessions. In the second experiment, the descending branch of the blood alcohol level (BAL) curve was monitored from .15 BAL, and cognitive and motor performances were assessed by the Automated Performance Test System (APTS) and FST. In the third experiment, the ascending and descending limbs of the alcohol dosage curve were followed. Dose-response relationships were conducted and were statistically significant (p < .001) in all three studies for all but one test when evaluated singly. Using either test battery, composite scores could be employed to index degraded performance from elevated blood alcohol levels. The best single test was gaze nystagmus from the FST battery and the next best was code substitution from the cognitive battery. Taken singly, the individual tests ranged from 66% to 81% in terms of correctly detecting the dichotomous criterion of < 0.10 versus 0.10 BAC and above. These results are discussed in the context of standards setting for driving under the influence (DUI) and the use of behavioral tests to evaluate over-the-counter and prescription drugs.
Evaluation of Pushbutton Arrangements in Automobiles BIBA 969-973
  Helmut T. Zwahlen
The need for more fingertip operated pushbuttons on automobile dashboards, consoles and steering wheels has increased over recent years with the emergence of new, sophisticated entertainment systems, driver aids, and communication devices. The space to place these controls within a driver's reach envelope has remained fairly constant, or has actually shrunk due to the down sizing of cars and the addition of crash protection devices. For this reason designers are forced to design smaller pushbuttons and to place these pushbuttons closer together in order to fit them into the allotted space along with the accompanying displays. With designers reducing the pushbutton sizes and putting them closer and closer together, the driver is forced to devote more time, more and/or longer foveal eye fixations, and more concentration to push the correct pushbutton. This could impose safety problems if too much time and concentration are diverted from the driving task. An exploratory study was conducted in the field, during daytime under fairly realistic conditions to examine the push location distributions when required to push exactly at a certain coordinate point in a car as a function of coordinate point location, car speed, driving task and road surface condition. This study resulted in a database of 5400 coordinate points of push locations. A model was developed to allow a designer to determine the size and spacing of round, square and rectangular pushbuttons based on a desired probability level of pushing the correct button. This model also takes into consideration the desired probability level of pushing any adjacent incorrect buttons. A computer program was developed based on the model and the experimentally collected data. The designer is required to enter information about the pushbutton shape, size, in car location, speed, road surface condition, driving task and the population percentile value of the fingertip width. The model uses a fingertip width concept which requires the user to input the distance expressed as a percentage of the fingertip width by which the fingertip center lies outside the button border and will still result in the activation of the pushbutton. The software then outputs the probabilities of pushing the correct, any adjacent incorrect, and none of the buttons. Correctly designed pushbutton arrangements (adequate size and spacing) should minimize activation time, foveal eye fixations, fixation times and errors resulting in fewer repeated pushes, which in turn, should improve safety while driving and operating pushbuttons in the modern automobile.

SAFETY: Arnold M. Small Lecture in Safety

Integrating Human Factors and Applied Behavior Analysis for Occupational Health and Safety BIB --
  E. Scott Geller

SAFETY: Perception of Risk and Warning Effectiveness

Effect of Warnings in Advertising on Adolescents' Perceptions of Risk for Alcohol Consumption BIBA 974-978
  N. Kimberly Bohannon; Stephen L. Young
The present study examined the effect of warning labels in alcohol advertising on the perception of risk for alcohol consumption. Under incidental conditions, subjects from two age groups, young (M = 13.6 years) and older (M = 23.3 years), examined a collection of magazine ads. Three of the ads in the booklet were for alcoholic beverages and these were either accompanied by a warning or the warning was absent. When present, the warnings were manipulated by the orthogonal combination of text voice (2nd vs. 3rd person) and pictorial (presence vs. absence) in a between-subjects design. A fifth condition served as the no-warning control. After examining the magazine ads, subjects answered a questionnaire which assessed several dimensions related to the ads: number and type of ads, attractiveness of the ads, and number and type of warnings in the ads. Examination of the questions dealing with the risk of alcohol consumption indicated that adolescents rated their own risk lower than the risk to adolescents in general, but that this bias in risk ratings was not evident when warnings were present. There were also several other age and gender effects. While no individual warning manipulation was found to be consistently superior to another, the results suggest that warnings can be effective in producing proper estimations of risk in different age populations.
Effect of Labels on Risk Perceptions of Consumer Products BIBA 979-983
  S. David Leonard; G. William, IV Hill
Previous studies have shown many individuals do not know the meanings of terms often used as stand-alone descriptions of hazards. Leonard and Digby (1992) found subjects rated the danger associated with different products very differently despite being given the same hazard description. One possibility for the differences in ratings is that substances are experienced in very different quantities. While gasoline is usually seen in multigallon amounts, fingernail polish remover is seen in quantities of a few fluid ounces. An alternative explanation is that people's experiences (direct or vicarious) with the substances have given them different concepts of the characteristics of the substances. This study examined these alternatives by asking 88 subjects to rate the risk of a dangerous event occurring with the same specific quantity of each substance. Mean ratings over all subgroups indicated that they perceived less risk from certain substances than from others, although the substances are equally dangerous. Evidence for an experiential component of risk assessment was provided by differences between older and younger subjects on specific items. The importance of presenting information about the consequences of hazards in warnings was discussed.
Toward a General Theory of Risk Perception BIBA 984-988
  Christopher William Schacherer
Several risk perception studies employing univariate techniques have found very strong predictors of risk perceptions, but these results are of limited use in describing the cognitive process that results in perception of risk. Also, although a few multivariate investigations have been conducted, the validity of the obtained results are similarly limited due to concern over deriving easily interpretable solutions. The present study, therefore, attempts to derive a more valid model of the risk perception process through confirmatory factor analysis based on previously reported findings.
The Ability of Two Lay Groups to Judge Product Warning Effectiveness BIBA 989-993
  J. Paul Frantz; James M. Miller; Bruce W. Main
How well can lay people assess the effectiveness or "adequacy" of product warnings without assistance from expert testimony? To begin to answer this question, two studies were conducted to determine the extent to which law students and engineering students could assess the relative effectiveness of two drain opener warning label designs. In the first experiment, only 18 of the 38 engineering students (47%) correctly identified the warning label design that had, in a previous study, been shown to be significantly more effective with similar subjects who actually used the product. In addition, these subjects did not accurately predict the likelihood that their peers would read and comply with the precautions. In the second experiment, only 14 of the 42 law students (33%) correctly identified the more effective of two label designs. This research contradicts several legal authors who postulate that juries are capable of determining the effectiveness of a warning unaided by well-founded expert testimony. More specifically, these studies do not support the assertion that the "knowledge of ordinary people" is sufficient to 1) distinguish between warnings that differ in their behavioral effectiveness and 2) accurately predict the likelihood that people such as themselves will read and heed safety instructions when using a product.

SAFETY: Industrial Safety and Personal Protection

The Safety Distance for Two-Hand Controls BIB --
  Harold G. White; Tarald O. Kvalseth
Industrial Robot Use: Survey Results and Hazard Analysis BIBA 994-998
  Fereydoun Aghazadeh; Robert Hirschfeld; Robert Chapleski
Robotic workcells have proliferated in recent years but safety guidance in the area of safety sensing devices has not kept pace. Research investigating current robot use was conducted through safety survey questionnaires returned from 29 robot using corporations across the nation. The research goal was to identify the hazards which workers are exposed to while working near robots. Only 5% of robots were found to have redundant sensing and 40% could not be physically enclosed in barrier perimeters. In addition, personnel were found to enter a robot's work area for 38% of an 8 hour day. Based upon the survey results, a hazard analysis was created to assist in the evaluation of robot workstation safety. The hazard analysis recommends that safety sensors should be integrated in a layered protection system with an external perimeter, an internal workzone area, and a software path monitoring system.
Psychophysical and Physical Techniques for Measuring the Attenuation of Hearing Protectors in the Field BIBA 999-1003
  Daniel W. Mauney
A field-implementable measure is needed to estimate the attenuation workers achieve with their hearing protectors in the field. Manufacturer-supplied values overestimate in-field attenuation and reliance on these values could result in greater noise exposure, thus contributing to hearing loss. Alternative measures for assessing a hearing protector's effectiveness were evaluated through comparison to the standardized real-ear attenuation at threshold (1/3-REAT) method (ANSI S3.19-1974). These measures, termed microphone in real ear (MIRE), used miniature microphones underneath and outside of the hearing protector to physically measure the attenuation of the protector using both insertion loss (IL-MIRE) and noise reduction (NR-MIRE) techniques. Results indicate that the MIRE measures differ significantly from the 1/3-REAT method (a psychophysical technique) for attenuation collapsed across protectors, with absolute differences as great as 6.6 dB and the direction of the difference changing due to frequency. At 125 Hz, the MIRE metrics yielded lower attenuation, while from 500 to 8000 Hz, the 1/3-REAT method generally yielded lower attenuation. These differences may be due in part to the occlusion effect and the bone conduction of sound. The size and consistency of these differences across HPDs suggest that these measures hold promise for providing quick and relatively accurate estimations of an HPD's attenuation in the field.
A Questionnaire Study of Accidents in Advanced Manufacturing Systems BIBA 1004-1008
  Jari Jarvinen; Waldemar Karwowski
Manufacturing automation has eliminated many traditional risks of injury, but new types of risks have appeared. In the United States only a limited amount of data is available on automated manufacturing-related accidents, or these data cannot be distinguished from general accident data. The purpose of this study was to collect data on accidents related to advanced manufacturing systems (CIMS). A questionnaire requesting information on one serious computer-integrated accident that occurred in the respondent's plant was used to collect the data. The presented results are based on the analysis of 85 cases. The cases included six fatal injuries, as well as several severe injuries that led to amputation. The results confirm the need to pay more attention to prevention of production disturbances in CIMS, especially in the case of material handling equipment. A relatively large amount of cases involving defeated safety devices calls for the design of intelligent safety systems that protect the human operator, but do not interfere with the work to be done, even during the disturbance situations.

SAFETY: Environmental and Nuclear Power Safety

Human Factors Issues in Environmental Incidents BIBA 1009-1013
  Harold E. (Smoke) Price
Current evidence suggests that human error or impaired human performance is a significant causal factor in environmental accidents and incidents. Some data from studies and analyses, accident investigations, and research is used to emphasize the extent of the problems. However, there are existing laws, regulations, or policy that require consideration of human factors in prevention of environmental incidents. Some specific requirements related to human factors are discussed. Finally, some areas for human factors contribution to environmental protection are discussed. These include such things as human error/ accident audit reviews, human reliability analyses as a part of risk assessment, root cause analyses of accidents, fitness-for-duty assessment, health and safety training, and human factors in the design of future hazardous or toxic process systems.
The State of Practice of Computerized Operating Procedures in the Commercial Nuclear Power Industry BIBA 1014-1018
  Anthony J. Spurgin; Jerry Wachtel; Parviz Moieni
The U.S. Nuclear Regulatory Commission (NRC) staff is presently reviewing human factors designs and development proposals for "advanced" reactors; plants that may be built in the future. One or more of these reactor designs will likely include some form of computerized emergency operating procedures systems (CEOPs) for use by plant operations personnel during transients and accidents.
   Twelve different CEOPs are known to be under development at the present time. These vary in terms of their philosophy (e.g. rule vs knowledge-based), their user interface, and their approach to function allocation and degree of automation. This study was undertaken to identify the salient characteristics of these systems in terms of their potential effects on control room crew performance and safe plant operation, as a first step in the development of guidelines by which the NRC can review such CEOPs prior to their implementation.
The Safety Climate of a Department of Energy Nuclear Facility: A Sociotechnical Analysis BIBA 1019-1023
  Allan E. Johnson; Jerry L. Harbour
Government- and public-sponsored groups are demanding greater accountability by the Department of Energy's weapons complex. Many demands have focused on the development of a positive safety climate, one that not only protects workers ornate, but also the surrounding populace and environment as well. These demands are in part a response to findings which demonstrate a close linkage between actual organizational safety performance and the organization's safety climate, i.e., the collective attitudes employees hold concerning the level of safety in their organization. This paper describes the approach taken in systematically assessing the safety climate at EG&G Rocky Flats Plant (RFP).
The Task Analysis Process for a New Reactor BIBA 1024-1028
  L. J. Staples
This paper discusses the application of the methodologies of Hierarchical Task Analysis (HTA) and Tabular Task Analysis (TTA), incorporating Human Error Analysis during the detailed design phase of a new reactor. The MAPLE-X10 reactor, currently being developed by AECL Research, is a dedicated isotope production facility, scheduled for commissioning at Chalk River Laboratories, Ontario in 1994.
   The task analysis process developed for MAPLE-X10 consists of the representation and analysis of task data. The aim is to ensure compatibility between the design of MAPLE-X10 and the characteristics and capabilities of the diverse users of the system. Compatibility will lead to enhanced safety, operability and maintainability. Each stage of the task analysis process is described and discussed, emphasizing the practical application of Hierarchical Task Analysis for task representation, and Tabular Task Analysis for detailed analysis of tasks during which human error may have safety or production related consequences.
   The benefits of applying the methods of Hierarchical Task Analysis and Tabular Task Analysis to the MAPLE-X10 project are highlighted. These include clear representation of the organization of tasks and interactions between systems in the HTA, continuous feedback to design and operations personnel regarding identified mismatches between existing procedures and the design intent, and cost effectiveness. The multiple uses of the information elicited during the task analysis process are also discussed in this paper. These include design verification, the identification of training requirements and the development / verification of operating procedures. In addition the task analyses provide a framework for other assessments to be completed for the project, such as Human Reliability Analysis, Workload Assessment, Communications Analysis and Training Needs Analysis for Mature Operations.

SPECIAL SESSIONS: Demonstrations

The Role of the Computer in Team Problem-Solving: Critiquing or Partial Automation? BIBA 1029
  Stephanie A. E. Guerlain; Philip J. Smith
A testbed was developed for studying the effects of different computer system designs on human-computer team problem-solving, using the real-world task of antibody identification. The computer interface was designed so that practitioners could solve antibody identification cases using the computer as they normally would using paper and pencil. A rule-base was then encoded into the computer such that it had knowledge for applying a heuristic strategy that is often helpful for solving cases. With this testbed, studies have been run comparing different computer system designs. A critiquing system was found to be better than a partially automated system on cases where the computer's knowledge is incompetent.
A User-Centered Approach to the Design of a Naval Tactical Workstation Interface BIBA 1030
  Christopher C. Heasly; Lisa A. Dutra; Mark, III Kirkpatrick; Thomas L. Seamster; Robert A. Lyons
The 21st century Navy combatant ship will experience exponential increases in shipboard information to be processed, disseminated and integrated. High Definition System (HDS) technology will provide for the convergence of text, graphics, digital video, imagery, and complex computing to allow for a new range of advanced capabilities that exceed those of currently available workstations. These capabilities could result in unmanageable and overwhelming cognitive workloads for Navy tactical operators in CIC (Combat Information Center). For this reason, a prototype user interface was designed using future combat system requirements, proposed HDS capabilities, and human-computer interface design standards and principles. Usability testing of the prototype user interface was conducted as part of an effort to identify integrated information management technologies which reduce operator workload, increase human performance, and improve combat system effectiveness.
   This demonstration will focus on explanation and demonstration of future concepts envisioned for the AEGIS operational environment; organization and functionality of the menu structures and window contents; the usability testing methods utilized; results from usability testing; and plans for utilization of the prototype shell in other operational environments.
SATORI: Situation Assessment Through Re-Creation of Incidents BIBA 1031
  Mark D. Rodgers
A system has been developed that graphically re-creates the radar data recorded at En Route air traffic control facilities. Each facility records data sent to the radar displays associated with the airspace under its control on a System Analysis Report (SAR) tape. SATORI (Situation Assessment Through Re-creation of Incidents) overlays the SAR data on the appropriate sector maps using map data from the Adaptation Control Environmental System (ACES) database. Voice records from the audiotape recording of the communications between the controller and pilots, and interphone communications are digitized and replayed in synchrony with the events displayed on the screen. Figure 1 details the SATORI data processing flow. The analog switch display settings of the PVD are not recorded, however subroutines have been written for SATORI that allow the display to be set up with the settings reported to have been used by a given controller. In addition to the above, SATORI has the capability to display the high and low weather intensity that was displayed on a given PVD. All software routines written for SATORI use Open Systems Foundation (OSF) technology. Similar data to those available from En Route facilities are recorded at TRACON facilities and should allow for the development of a re-creation tool much like the one discussed in this report. Once SATORI is evaluated, it will be possible to accomplish the goals of evaluating system designs, over-the-shoulder appraisals, training outcomes, and measuring controller performance.
Active Man Machine Interface for Advanced Rotorcraft BIBA 1032
  Monica Z. Weiland; Brian A. Convery; Allen L. Zaklad; Wayne W. Zachary; Clarence A. Fry; James W. Voorhees
The proliferation of digital avionic information presented to pilots has produced a critical need for intelligent avionic information management, particularly in the area of Caution, Warning, and Advisory (CWA) systems. This demonstration illustrates the role of an Active Man Machine Interface (AMMI) in the context of CWA systems in rotorcraft of the future. The basis of the AMMI's intelligence demonstrated here is provided by a cognitive model that 1) prunes the alert stream to only those messages that have meaning to the pilot depending on the tactical context, and 2) provide context-sensitive advice on the basis of the tactical context. The CWA AMMI is currently being designed using COGNET, an cognitive modelling methodology (Zachary, 1989), and implemented using BATON, a set of software tools used to implement and embed COGNET models into existing systems (Zachary et al, 1991).
Integrated Decision/Engineering Aid (IDEA) -- Enhancements BIBA 1033
  Christopher C. Heasly; Thomas B. Malone
Integrated Decision/Engineering Aid (IDEA) incorporates a standard process and a set of automated tools to support the application of the Department of Defense's Human/System Integration (HSI) program, the Army's Manpower and Personnel Integration (MANPRINT) initiative and Human Factors Engineering (HFE) throughout the materiel development process. IDEA provides the HSI/HFE analyst with guidelines, data and tools to integrate HSI/HFE into the acquisition of: (a) non-developmental items (NDI), (b) product improvements, and (c) new system developments, focusing on the activities and products at each phase of the materiel acquisition process.
   The purpose of the session is to demonstrate how IDEA is utilized in the definition of the HSI/MANPRINT requirements in support of the system development/acquisition process. Emphasis will be placed on a review of the overall architecture, arrangement and organization of the modules, and on the recent additions and modifications.
Developing the User-System Interface for a Communications System for ALS Patients: The Results BIBA 1034
  Robert A. Murphy; Annamaria Basili
Blink-writer is a communications system created to help restore the ability to communicate to the severely neurologically impaired. The system has been used successfully on patients with amyotrophic lateral sclerosis (ALS), on stroke victims, on patients with high spinal cord injury, and on a patient who was paralyzed as a result of having contracted bulbar polio.
The Development of an Interactive Multimedia Tour of Human Factors at Virginia Tech BIBA 1035
  Wayne C. Neale; Robert H. Miller; Richard H. Miller
This paper discusses some of the more important issues concerning the development of interactive multimedia systems. Specifically, the design of a multimedia tour or interactive presentation of human factors and ergonomics at Virginia Tech is demonstrated.
Interface Evaluation and Enhancements to the Image Access and Management System for Space Shuttle Earth-Looking Photography BIBA 1036
  Kevin O'Brien; Benjamin Beberness; Steve Chrisman; Frances E. Mount; Gary Seloff
The Image Access and Management System (IAMS) is being developed to provide easy access to photographic images taken by Space Shuttle astronauts. The photographs, coupled with a textual catalogue of descriptive characteristics, forms a significant database of information about the Earth's surface. The IAMS incorporates a video laser disc containing digitized images, an electronic database containing descriptive information about each photo, and software allowing the database to be searched and the images to be viewed. The demonstration presents the IAMS and the unique interface development issues involved with a photographic image/database system.
New Directions in Task Analysis BIBA 1037
  Alan P. Wier
A demonstration of a new graphic notation system which expands the existing symbol set associated with operational sequence diagrams. The notation system is being developed as part of a computer-aided instructional program created for undergraduate students involved in human factor studies. The basic premise of the notation system is to enhance the practitioners understanding of human-machine processes during task analysis and operational sequence diagraming.
User Interface Design Guidance Systems BIBA 1038
  Louis A. Blatt; James F. Knutson
Despite the wide acceptance of standard user interface platforms, style guides, and software tools, many human-system interfaces are still difficult to use. An user interface design guidance system (UIDGS) is any collection of tools that supports a software developer or designer in creating human-system interfaces. Current UIDGSs are insufficient. Some criticisms of design guideline documents, a popular form of UIDGS, are that they do little to ensure task consistency (Potter et al., 1990), are not well-suited for use during development (Thovtrup and Nielsen, 1991), are often too general (Chapanis, 1990) and are perceived as limiting creativity. These factors have inhibited the adoption of UIDGSs within the mainstream of software development. The current research addresses this problem through demonstration of a prototype UIDGS.
Contaminant Analysis Automation Demonstration Proposal BIBA 1039
  Mike G. Dodson; Anne Schur; Janet G. Heubach
The nation-wide and global need for environmental restoration and waste remediation (ER & WR) presents significant challenges to the analytical chemistry laboratory. The expansion of ER & WR programs forces an increase in the volume of samples processed and the demand for analysis data. To handle this expanding volume, productivity must be increased. However, the need for significantly increased productivity faces a contaminant analysis process which is costly in time, labor, equipment, and safety protection. Laboratory automation offers a cost effective approach to meeting current and future contaminant analytical laboratory needs.
   The proposed demonstration will present a proof-of-concept automated laboratory conducting varied sample preparations. This automated process also highlights a graphical user interface that provides supervisory control and monitoring of the automated process. The demonstration provides affirming answers to the following questions about laboratory automation:
  • Can preparation of contaminants be successfully automated?
  • Can a full-scale working proof-of-concept automated laboratory be developed
       that is capable of preparing contaminant and hazardous chemical samples?
  • Can the automated processes be seamlessly integrated and controlled?
  • Can the automated laboratory be customized through readily convertible
       design?
  • Can automated sample preparation concepts be extended to the other phases of
       the sample analysis process? To fully reap the benefits of automation, four human factors areas should be studied and the outputs used to increase the efficiency of laboratory automation. These areas include: 1) laboratory configuration, 2) procedures, 3) receptacles and fixtures, and 4) human-computer interface for the full automated system and complex laboratory information management systems.
  • High Definition Systems Usability Test Tool (HUTT): A Human-Computer Interface Prototyping Tool BIBA 1040
      Christopher C. Heasly; Lisa A. Dutra; Mark, III Kirkpatrick; Thomas L. Seamster; Robert A. Lyons
    The High Definition Systems Usability Test Tool (HUTS) was developed to demonstrate and assess different human-computer interface (HCI) concepts for generic operator console positions within an advanced naval tactical display environment. To facilitate a "rapid prototyping" approach to interface development, HUTT was developed as a general purpose tool. The HUTT can be used by the human factors engineer as a rapid prototyping tool enabling quick construction and evaluation of alternative interface concepts. Changes to the organization and operation of a prototype can be made quickly, ensuring that more time can be spent on evaluation as compared to development.
       The demonstration will focus on the uses and operation of the HUTT. Demonstration participants will be shown how to develop, install and modify the OSF/Motif compliant graphics (pull-down menu structure and window contents) and the functionality of the HUTT to reflect changes in interface concepts.
    InterView: A Software Tool for Interface Design BIBA 1041
      Maxwell J. Wells; Robert K. Osgood
    InterView is a software tool for designing, specifying and visualizing human-machine interfaces. The design of the tool began with two premises. The first is that, in order to adequately specify an interface, a designer must consider the inputs, outputs, and states of the system for which the interface is being designed. In this context, inputs refer to user-to-system communications, as mediated through buttons, keyboards, etc. Outputs refer to system-to-user communications, as mediated by displays, or other feedback. States refer to discrete conditions, either real or conceptual, in which the system may be at a given time. The second premise is that good, clear diagrams play an essential part in designing complex systems. Given appropriate diagramming techniques, it is much easier to describe complex activities and procedures in diagrams than in text. A picture can be worth more than a thousand words, because it is concise, precise, and clear. It does not allow the sloppiness and possibilities for misinterpretation that are common in text specifications.
    A Tool for Automatically Generating Transcripts of Human-Computer Interaction BIBA 1042
      James H. Hicinbothom; Wayne W. Zachary
    Recording transcripts of human-computer interaction can be a very time-consuming activity. This demonstration presents a new technology to automatically capture such transcripts in Open Systems environments (e.g., from graphical user interfaces running on the X Window System). This technology forms an infrastructure for performing distributed usability testing and human-computer interaction research, by providing integrated data capture, storage, browsing, retrieval, and export capabilities. It may lead to evaluation cost reductions throughout the software development life cycle.
    Environmental Constraint of Human Movement: A New Computer-Aided Approach BIBA 1043
      David B. Lantrip
    This session demonstrates a computer program, called MacISOKIN, that reveals where and how the physical environment constrains the movements of inhabitants. An associated research paper explains how ISOKIN measures of environmental constraint are related to the environmental satisfaction of office workers. MacISOKIN was recently developed to facilitate a research project sponsored by Steelcase, Inc. at the University of Michigan.
       The demonstration emphasizes how this computer-aided approach can assist designers and planners with the critical design tradeoffs inherent in limited space scenarios. MacISOKIN provides color graphics and numerical reports to identify areas in a floorplan where furnishings or the activities of other inhabitants are a likely source of interference. The "object-oriented" user interface allows the user to quickly change numerous analysis variables. For example, the impact of alternative layouts may be tested by adding, deleting or moving a wall or furnishing. Alternative activity scenarios may be explored by cutting and pasting "body-motion envelopes" from a library of pre-analyzed activities.
    Comparative Anatomy Maintenance Tasks (CAMT): Database Feasibility Study Field Administration Technology Demonstration BIBA 1044
      Donald R. Loose; Frank C. Gentner
    To be a "player" in today's concurrent engineering design environment, engineers must provide reasonable estimates of system-level effects for their recommendations. Human factors engineers (HFEs), who formerly relied on quoting military standards or design guides, now must support their recommendations with consequences. Although human factors maintainability estimate methods have been employed, most are considered cumbersome, labor intensive, and not responsive to the quick-paced program or design office. CAMT proposes a new way to collect, organize, and estimate human consequences of design alternatives. This method is being demonstrated in a series of CAMT feasibility studies by the Armstrong Laboratory Logistics Research Division.
    PVAT -- A Posture Video Analysis Tool BIBA 1045
      Darlene Merced-Moore; Susan C. Adam
    The Posture Video Analysis Tool (PVAT) has been developed to meet the special needs of ergonomist and human factors analyst at NASA Johnson Space Center. Often times these specialist must attempt to evaluate microgravity working posture from video footage not specifically recorded for the purposes of quantitative analysis. The purpose for developing PVAT was to provide a structured methodology in which these specialists could optimize the data collection technique. The PVAT is designed such that microgravity postures can be documented while systematically observing footage of astronauts working in a space environment. PVAT is an interactive Macintosh menu and button driven Supercard prototype. Users are provided with a set of input parameters related to the microgravity environment and human performance issues. The primary inputs are: subject code, body orientation, targeted body part camera view (given subject location), body movement and rating level. A secondary set of inputs is available for users wishing to document extraneous behaviors or activities such as bending, reaching, interruptions, etc. These secondary behaviors may be documented as part of the primary inputs or independently. Each entry is time stamped and stored automatically. Provisions are made that allow users to pause, tag incorrect selections, enter an "unsure" response and user comments. Data output is saved as a "text file" using tab delimiters for easy importation into programs such as Microsoft EXCEL. Future PVAT modifications will include adding more input parameters, data reduction capabilities, control of the video deck from the application, and an animated postural glossary.

    SYSTEM DEVELOPMENT: Viewing Complexity in System Development

    Human Factoring the Procedures Element in a Complex Manufacturing System BIBA 1046-1050
      D. J. Caccamise; M. Mecherikoff
    As a result of Human Factors evaluations of procedures associated with incidents at Rocky Flats Plant (RFP) it was determined that the existing procedure format created significant opportunities for confusion in their attempt to convey information about a work process. For instance, there was no mechanism to clearly identify the participants and their roles during the Instructions portion of the procedure. In addition, procedure authors frequently used complex logic to convey a series of contingent actions within steps. It was also difficult to discern the actual procedure steps from other types of information in the procedure. These and other inadequacies prompted the Human Factors Engineering (HFE) department to propose solutions to these problems that followed well-researched principles of cognitive psychology, dealing with how humans process information. Format and style contribute to procedure usability, and therefore to safety and efficiency in operations governed by the procedures. Since it was difficult to tie specific performance failures to specific format and style characteristics and thereby clearly define costs and benefits, it was difficult on that basis to sell the idea that changes in procedure format and style were really necessary to improve safety and efficiency. In addition, we found that the socio-political systems governing this process, particularly at the subprocess interface level, were not functioning efficiently. Both the technological aspects of the process and the socio-political aspects were contributing to waste and considerable re-work. Fixing the customer feedback loop to the process owners not only minimized re-work and waste, but also provided the data to persuade subprocess owners to make the necessary changes that heretofore were being met with great resistance.
    The Effect of Variations in Operator Proficiency on ASW Combat System Performance BIBA 1051-1055
      Milt Stretton; Daniel Bowdler; Jane Conway; Dick Swiontek; John Morris; John Wachter
    The development of an operability model analysis tool to support design requirement definition for advanced ASW combat systems has evolved over the last four years. Previous NUWC ASW Combat System Operability Modeling efforts using SLAM II have produced comparisons between various ASW combat systems to examine the relative benefits of equipment features and operating concepts. Development of these operability models enabled the representation of contact data handling processes, ASW combat system operators, and the man-to-man, man-to-machine, and machine-to-machine interfaces that occur during an ASW mission. Early operability model studies (Stretton, Swiontek, Morris, Conway, and Wachter, 1991) investigated data handling bottlenecks and contact data throughput for ASW systems by focusing on the sensor operators, supervisory personnel, and command decision makers. Earlier models did not incorporate variations in team member productivity as might be found under high-workload conditions. Also, ASW team member skill levels were not varied as might be found due to latency from training-to-shipboard activities or to individual differences in operators and their training. As a follow-on effort, this study examined how variations in operator proficiency on critical tasks affect overall ASW combat system performance. Results of this effort appear to have wide-reaching operational impacts in the area of team performance and operator variability.
    Enhancing Crew Coordination in Advanced Control Rooms BIB --
      William F. Stubler; Emilie M. Roth
    AT&T Image Analysis System Development for Manual Lifts BIBA 1056-1059
      Bahador Ghahramani; Lawrence B. Fleischer; Jerome J. Congleton; Joseph W. Foster
    AT&T Video Ergonomics Evaluator System (AT&T-VEE) is a state-of-the-art computer analysis system used to analyze the hazards of a Manual Material Handling (MMH) task. This project was funded and managed by the American Telephone & Telegraph Company (AT&T) and designed and developed at Texas A&M University. The system is a lifting analyses tool for the 1992 NIOSH Lifting Equation to determine minimal user effort in lifting an object and to standardize the outputs. This system is now capable of providing the AT&T safety specialists with clear access to: complete NIOSH analyses, pictures of the lift environment, and background information on the MMH process.
       It was determined that a system, such as AT&T-VEE, was needed to reduce AT&T's MMH injuries and ensuing problems. The scope of the project was to develop a menu driven, user friendly system that would provide employees with the ability to determine the maximum weight of objects utilized at MMH tasks. In order to perform a lifting analysis, a video tape of a manual lift is first produced. The system user, in conjunction with a computer, enters employee's measurement landmarks and points of analyses, e.g., ankles, load center, weight, etc. AT&T-VEE produces a NIOSH Lifting Equation analyses, pictures and records of the MMH task.

    SYSTEM DEVELOPMENT: Panel

    Plowshares Human Factors: Conversion Success Stories and Opportunities BIBA 1060-1061
      John F. Brock; Kay Inaba; Robert North; Lisa Dutra; Fred Muckler; Doug Griffith
    To provide a forum to discuss how system development techniques and approaches which have proved successful for weapon systems can be applied to the design and development of non defense related systems.

    SYSTEM DEVELOPMENT: Developing Human Factors Guidelines for Intelligent Vehicle/Highway Systems: First Progress Report

    Developing Human Factors Guidelines for Intelligent Vehicle/Highway Systems: First Progress Report BIB --
      Barry H. Kantowitz
    Assessing Driver Acceptance of IVHS Components BIBA 1062-1066
      Barry H. Kantowitz; Curtis A. Becker; S. Todd Barlow
    From a human factors perspective, ATIS and CVO are key components of IVHS. But impressive technology does not guarantee consumer acceptance. Several issues concerning acceptance of new technology are discussed including product characteristics, consumer characteristics, and implications for CVO. Two experiments that evaluate driver acceptance are described.
    Human Factors Research Recommendations for the Development of Design Guidelines for Advanced Traveler Information Systems BIBA 1067-1071
      Thomas A. Dingus; Melissa C. Hulse
    This paper describes the outcome of a comprehensive literature review specifically conducted to assess research relevant to the design of advanced traveler information systems (ATIS) for automotive and commercial vehicle use. The goal of the literature review was to identify existing human factors guidelines applicable to the design of ATIS and gaps in the research precluding the development of comprehensive human factors guidelines for ATIS applications. A summary of ATIS research findings and research gaps is presented. Through presentation of both research findings and research gaps, it is hoped that interest will be sparked and focus will be provided for researchers in this growing application of human factors. Given the criticality of ATIS applications (both in terms of driver safety and public acceptance) and the visibility that will be provided to the human factors community from participation in ATIS design, human factors research leading to comprehensive and usable guidelines is extremely important.
    System Objectives and Performance Requirements of ATIS and Commercial Vehicle Components of IVHS BIBA 1072-1076
      Marvin C. McCallum; John D. Lee
    This paper describes a recently completed survey conducted to determine the transportation community's perspective on Advanced Traveler Information System (ATIS) and Commercial Vehicle Operations (CVO) system development objectives and performance requirements. The paper describes the research methods, some general findings regarding development objectives, and a general discussion and examples of performance requirements.
    User Information Requirements for Intelligent Vehicle Highway Systems as a Function of Driver Category BIBA 1077-1081
      Linda Ng; Woodrow Barfield
    Advanced Traveler Information Systems/Commercial Vehicle Operations (ATIS/CVO) are segments of IVHS currently being researched as a means of decreasing road congestion and increasing safety. Due to the complex information requirements for these systems, three surveys have been designed by University of Washington researchers and distributed nationwide to collect these requirements from the users: commercial drivers, dispatchers and private vehicle drivers. This paper discusses the methodology used to design the surveys and the effort to ensure that a representative sample was included on a nationwide basis. Approximately 8,300 surveys were distributed in person and 10,000 dispatcher surveys were distributed in a newsletter. Data estimation procedures will include modeling the influence of an in-vehicle system for route guidance and determining the significant impacts of an ATIS/CVO in terms of age, gender, income, and other socioeconomic characteristics.

    SYSTEM DEVELOPMENT: Design Issues in System Development

    Understanding the Context of Multidisciplinary Design: Establishing Ecological Validity in the Study of Design Problem Solving BIBA 1082-1086
      Michael D. McNeese; Brian S. Zaff; Clifford E. Brown; Maryalice Citera; Jonathan Selvaraj
    The need to understand the design process in all its complexity is motivated by an interest in the development of tools and technologies that would be capable of aiding collaborative design teams. This development effort depends upon an understanding of design activities as they occur within a real world context. Observations of design activities that are made without direct communication with the design team members may fail to capture many of the subtler aspects of the process -- aspects that are best understood when described by the design team members themselves. In order to supplement observational studies, this paper presents a case study in which a dialog with members of a variety of collaborative design teams was established in order to elicit information about the nature of collaborative design. A knowledge acquisition technique, concept mapping, was used to achieve an understanding of the role of human factors specialists within the collaborative design process specific to the Air Force's system acquisition program. Results highlight various findings about the nature of design problem solving such as the way different organizational settings influence human factors input in the design process/product. The paper discusses the usefulness of concept mapping to capture in-depth design knowledge and how this type of knowledge complements other approaches to understanding design.
    Bringing Human Performance Data to the Design Table BIBA 1087-1090
      Thomas R. Cona; Donald L. Monk
    Product design is often viewed as being a heterarchical and iterative process, possessing both systematic and chaotic qualities. However, a common denominator across all design activities is the access and utilization of information. In today's computer-aided design market, most of the available tools are narrowly focused on specific computational details for individual stages of design. Aids are needed to support information access and utilization during all stages of the design process.
       The application of human engineering and ergonomics data by designers is an increasingly challenging problem. Locating and understanding relevant information so that it can be applied to specific design issues is difficult given the abundance of existing and new data available. This is further complicated, in that the data are typically written to communicate research results to other human factors specialists.
       A new software product, Computer Aided Systems Human Engineering: Performance Visualization Subsystem (CASHE:PVS), is described which will assist the designer during the decision making process maximizing creative and analytical abilities while minimizing costs due to design time and errors. The software contains several features to enhance the designer's ability to interpret and apply the human factors data available in the product. Phenomena descriptions in text, figures, and tables are combined with experiential information via simulations, animations, and audio. This provides the user a unique and rich understanding of human performance phenomena and how they relate to the design of new products.
    Design-Induced Error in Flight Planning BIBA 1091-1095
      Philip J. Smith; Elaine McCoy; Chuck Layton
    There are many problem-solving tasks that are too complex to fully automate given the current state of technology. Nevertheless, significant improvements in overall system performance could result from the introduction of well-designed computer aids. A major concern in the introduction of such tools to support problem-solving, though, is the potential to introduce new errors due to the interaction of the person with these computer support tools.
       We have been studying the development of cognitive tools for one such problem-solving task, enroute flight path planning for commercial airlines. Our goal has been two-fold. First, we have been developing specific system designs to help with this important practical problem. Second, we have been using this context to explore general design concepts to guide in the development of cooperative problem-solving systems. These design concepts are described below, along with a discussion of two empirical studies.
    Procedures Software Tool Requirements Analysis BIBA 1096-1100
      Marvin C. McCallum; Jennifer Morgan; Joseph Y. Yasutake; Hachiro Isoda
    This paper describes a recently completed project conducted to identify functional requirements and software features of a Procedure Software Tool (PST) to be used as an aid in the preparation of written maintenance procedures in nuclear power plants. Results discussed include an overview of functional requirements and software features that address problems in procedure use and the process of procedure development. An overview of the recommended PST development process is also provided, along with a summary of the estimated benefits of PST development. Finally, potential applications in the nuclear industry, as well as other industries, are discussed.

    SYSTEM DEVELOPMENT: Perspectives on Decision Analysis for Decision Support System Design

    Perspectives on Decision Analysis for Decision Support System Design BIBA 1101
      Barbara J. Barnett
    This symposium addresses the characterization of human decision making within a complex environment for the purpose of developing improved decision support systems. All of the work presented in this symposium was conducted under a Navy research program entitled "Tactical Decision Making Under Stress" (TADMUS). The overall objective of the TADMUS program is to improve tactical decision making of anti-air warfare (AAW) crew members within the Aegis cruiser's combat information center (CIC) under conditions of stress and uncertainty. The unique aspect of this effort is that each presentation addresses decision making behavior, within a single domain, from a different perspective. The goal of each effort is to characterize some aspect of expert decision making performance within the AAW task environment, and to make recommendations for the resulting decision support system design based upon these characterizations. The result is a multi-faceted, human-centered approach to information organization and interface display design for a decision support system.
    Metacognitive Strategies in Support of Recognition BIBA 1102-1106
      Marvin S. Cohen
    Recent research on decision making has focused on complex real-world domains and experienced decision makers, in contrast to artificial tasks and novice subjects (e.g., Klein et al., 1993). This research has produced a revised view of decision making, one that stresses knowledge-based, recognitional processing rather than general-purpose, analytical methods. Nevertheless, a full understanding of recognitional processing and its implications for the design of decision aids has not yet been achieved. In particular, the active, controlled aspects of recognitional processing have not been fully accounted for in approaches that stress relatively automatic pattern recognition as the basis for responding.
    Decision Making in the AEGIS Combat Information Center BIBA 1107-1111
      George L. Kaempf; Steve Wolf; Thomas E. Miller
    This paper presents the methods and findings of a study designed to identify the decision requirements for anti-air warfare officers in the Combat Information Center of an AEGIS cruiser. Decision requirements include the decisions that systems operators make, the cognitive strategies they invoke to make these decisions, and the cues and factors essential for making these decisions. These requirements can be used to design training, human-computer interfaces, or decision supports. The researchers adopted a method based on Naturalistic Decision Making (NDM) research. NDM describes how people make decisions in real-world settings under conditions of time pressure, high risk, and ambiguity. This paper describes a process for obtaining data necessary for describing these decision processes. The central method is a semi-structured interview method, the Critical Decision method (CDM). CDM was used to interview 31 experienced AEGIS personnel resulting in 14 incidents that reflect real problems experienced by the operational fleet. Analysis of these incidents revealed 183 decisions. Of these, 103 concerned situation assessments (SA). The operators used feature matching and story building to make all SA decisions. The operators invoked recognitional strategies to generate 95% of the course of action (COA) options and compared multiple options in only 5% of the COA decisions. The findings reported here indicate that under conditions of time pressure and ambiguity: decision makers rarely use analytical decision strategies, they usually satisfice rather than optimize, they rely heavily on diagnostic decisions, and they invoke singular rather than comparative evaluations of courses of action.
    COGNET Representation of Tactical Decision-Making in Anti-Air Warfare BIBA 1112-1116
      Wayne W. Zachary; Allen L. Zaklad; James H. Hicinbothom; Joan M. Ryder; Janine A. Purcell
    Human tactical decision making in Naval Anti-Air Warfare (AAW) is time-critical and is performed in a multiple-task, team-based environment. These aspects make this domain extremely challenging for traditional cognitive modeling techniques. The COGNET (COGnition as a NEtwork of Tasks) framework, however, is inherently designed for real-time, multi-tasking work, and, with extensions to accommodate team decision processes, proved suitable for modeling AAW decision making in the Navy's Tactical Decision Making Under Stress (TADMUS) program. A COGNET model of AAW domain expertise is described, along with Decision-Support System (DSS) design principles derived from the COGNET AAW model and the underlying COGNET framework.
    Decision Making Bias in Complex Task Environments BIBA 1117-1121
      Bruce M. Perrin; Barbara J. Barnett; Larry C. Walrath
    This presentation summarizes the results of an empirical study examining human judgment bias under conditions of uncertainty and time pressure in surface Anti-Air Warfare (AAW). A substantial body of research has demonstrated that humans apply a limited set of heuristics to simplify decision making in complex and ambiguous situations. Most of this research, however, has used college students making logical, but unfamiliar judgments. This study was designed to assess whether Naval personnel, trained and experienced in AAW operations, exhibit these biases when performing their normal duties. Specifically, we studied whether the judgments of Naval tactical action officers in a realistic task simulation exhibit characteristics of the biases of availability, representativeness, anchoring-contrast, and confirmation. Our prediction that experienced subjects would disregard lack of reliability in otherwise representative data was only partially supported by the study. On the other hand, each of our other predictions was strongly supported. Our subjects ignored baseline trends when other case-specific information was available (representativeness and availability). They were significantly influenced by the order they received evidence, showing a recency effect characteristic of contrast. Additionally, as is characteristic of confirmation bias, they recalled much more of the information that was consistent with their final hypothesis and evaluated it as more informative than the inconsistent data, regardless of which hypothesis they had adopted. Implications for Naval decision support systems information and display are discussed.

    SYSTEM DEVELOPMENT: Panel

    Using Decision Support Centers in the Human Computer Interface Product Development Cycle BIBA 1122-1126
      Brian P. Burns; Stephen R. Ruth; Elizabeth A. Muncher; Stephen Hayne; Gerard P., Sr. Learmonth
    In the commercial design of human computer interfaces, two of the most important goals for development of a new or enhanced business system or product is to increase the company's profit and market share. The most practical way to accomplish these goals is to reduce the project development cycle to yield a higher return on investment.
       A balance must be maintained to ensure that the reduction in cycle time does not compromise users' needs. Reducing development time and cost will have minimal effect if users will not accept the final product.
       During the past decades, new life cycle development techniques and tools have evolved to reduce the development cycle and increase user acceptance. Since the mid 1980's Joint Application Development (JAD) techniques, Decision Support Center (DSC), rapid prototyping and CASE tools have been introduced. These techniques and tools have focused on improving the front-end development process to understand the requirements and design prior to implementation.

    TEST AND EVALUATION: Usability Evaluations

    Retrospective versus Concurrent Thinking-Out-Loud in Usability Testing BIBA 1127-1131
      Kenneth R. Ohnemus; David W. Biers
    This study examined the effect of concurrent and retrospective thinking-out-loud (TOL) on the frequency and value of user verbalizations during a software usability test. Three groups of users first learned to use an off-the-shelf database management package by means of a short tutorial and then engaged in six structured tasks. Users in the Concurrent condition thought-out-loud while performing the six tasks, whereas those in Retrospective-Immediate and Retrospective-Delayed conditions thought-out-loud while watching the videotape of their interaction with the software. Results indicated that there were no significant differences among the three conditions in performance or subjective evaluation of the software. More importantly, a verbal protocol analysis revealed that users in the Retrospective conditions spent more time making statements which had high value for designers than in the Concurrent condition. The value of verbalizations generated by the Retrospective conditions were not impacted by the 24 hour delay. The results were interpreted within context of differences in workload and in terms of the trade-off between increased value gained by using the retrospective paradigm versus increased cost of additional time to conduct the usability test.
    Enhancing the Performance of Interface Evaluators Using Non-Empirical Usability Methods BIBA 1132-1136
      Heather Desurvire; John C. Thomas
    Heuristic Evaluation has been shown to be a quick cost-effective methodology that can lead to early identification of many of the same user interface errors as laboratory usability studies. In this paper, we describe a method designed to enhance the performance of expert, system developer, and non-expert evaluators. The evaluators most proficient at Heuristic Evaluation are Human-Factors Experts (Desurvire, Lawrence and Atwood 1991; Desurvire, Kondziela and Atwood, 1992; Jeffries, Miller, Wharton and Uyeda, 199i) and most notably, "double experts" (Nielsen, 1992). Similar results were obtained for the Cognitive Walkthrough developed by Lewis, Polson, Wharton and Rieman, 1990 (Desurvire, et al., 1992; Jeffries, et al., 1991). We were interested in whether a non-empirical method could be developed in which evaluators other than Human Factors Experts can perform nearly as well as Experts.
       Desurvire, et al. (1992) found that Heuristic Evaluation and Cognitive Walkthroughs not only predicted problems observed in laboratory studies but also encouraged evaluators to suggest improvements. In addition, non-empirical methods stimulated evaluators to point out problems that would be likely to occur in actual use, but would not be observed in laboratory studies. We were interested in expanding this finding by developing a method that encouraged a broader scope of thinking, and thus a broader evaluation. In this paper, we describe the method Programmed Amplification of Valuable Experts (PAVE) and how it enhanced the performance of System Developers and Non-Human-Factors-Expert evaluators. Future work is discussed in which real users in the field will be compared to these results.
    A Methodology and Encoding Scheme for Evaluating the Usability of Graphical, Direct Manipulation Style Interfaces BIBA 1137-1141
      Donna L. Cuomo
    A model-based method for assessing the usability of graphical, direct manipulation style interfaces was developed and applied to a military airspace scheduling system. The method involves collecting and integrating verbal protocol data and mouse/keystroke files, and having an analyst familiar with the task, the data, and Norman's (1986) user activity model review the data and make determinations on what the data mean in terms of the model. A hierarchical encoding scheme based on the model is then applied to the integrated data to structure the human-computer interaction (HCI) process at a detailed interaction level. Meaningful patterns can be identified, frequency of events per task, and number of actions per intention can be calculated at various levels in the hierarchical breakdown, highlighting potential usability problems or instances of indirectness. Repetitious sequences, for example, could imply a missing high-level task domain object or an inability to group objects for application of a single action. Detailed model-based error encodings reflect user-system interface difficulties not only in the execution stage of HCI but in the psychological stages as well. The types of usability problems identified and the advantages of the method arc discussed. Based on these results, we have begun developing a multi-media tool to support application of the method.
    On-Screen Keyboards: Which Arrangements Should be Used? BIBA 1142-1146
      Laurie L. Quill; David W. Biers
    The purpose of the present study was to test and evaluate three on-screen keyboard arrangements with indirect input devices. Studies conducted for hard keyboard arrangements have considered various factors affecting typing; however, differences between the nature of the hard and on-screen keyboards tasks preclude extrapolation from hard keyboard studies to on-screen keyboard designs. In this study, Finger Placement and Non-Finger Placement typists provided data for Stimuli (Word vs. Non-Words), Devices (Mouse vs. Arrow Keys), and Keyboards (1-Row Alphabetical, 3-Row Alphabetical, and QWERTY arrangements). The primary data collection tasks were two movement tasks and a typing task. The typing task consisted of having the user type a given Stimulus utilizing one of the on-screen keyboard arrangements and input devices. The movement task served as a control for movement time in the typing task. At the conclusion of the study, users were asked to rank order their preference for keyboard arrangement and input device. The QWERTY keyboard resulted in the fastest overall input times, and was the most preferred arrangement overall. Interaction between Device and Keyboard showed that with the mouse, input times for the 1-Row Alphabetical were slower than the QWERTY; whereas, with the arrow keys, input times were equivalent. However, this change in relative performance under the 1-Row Alphabetical arrangement for the two devices can be simply attributed to movement time. After statistically removing the effects of movement time from the typing task, the 1-Row Alphabetical arrangement was equivalent to the QWERTY for both input devices. Conclusions suggest potential incompatibility between the mouse interface and the 1-Row Alphabetical arrangement used in this study.

    TEST AND EVALUATION: T&E Theory and Application

    Meta-Analysis of Multiple-Task Performances: Cumulating the First Two Decades of Research Findings Across Studies BIBA 1147-1151
      Georgia K. Green
    Meta-analytic procedures were used to cumulate research findings across studies of multiple-task performances published between 1965 and 1985 (inclusive). Exhaustive literature search yielded 94 reports of studies of multiple-task performances that were sufficiently detailed to be statistically combined using the Hunter-Schmidt-Jackson procedure. These studies yielded a total of 202 statistical values and a total subject N of 3091. Meta-analysis was performed overall (resulting in a significant test statistic) and then as a function of secondary task (13 types), primary task (18 types), and specific secondary-primary task combination. (The secondary tasks were Choice Reaction Time (CRT), Classification, Detection, Memory, Mental Math, Monitoring, Motor Response, Problem Solving, Reaction Time, Shadowing, Speech, Task Battery (Multiple Tasks), and Tracking; the primary tasks were Association, CRT, Classification, Decision Making, Detection, Driving, Flight (Simulation), Memory, Mental Math, Monitoring, Motor Response, Problem Solving, Reading, Shadowing, Sketching, Speech, Tapping, and Tracking.) Ten external variables (Carbon Monoxide, Control-Display Compatibility, Drug Use, Feedback, Intelligence Tests, Neuroticism, Noise, Rating of Job Performance, Sinus Arrhythmia, and Temperature) as correlates of multiple-task performances were also examined. A generally positive relationship between secondary task performance alone and in combination with the primary task was found, along with moderating effects of secondary task type and primary task type. No substantial variation of results within a given combination of secondary and primary task types occurred in most cases, although four external variables (Carbon Monoxide, Feedback, Noise, and Temperature) displayed within-factor variation of results. All results were discussed in terms of integration of the past literature and directions for future research.
    Evaluating Expertise in a Complex Domain -- Measures Based on Theory BIBA 1152-1155
      Jean MacMillan; Eileen B. Entin; Daniel Serfaty
    Human factors practitioners are often concerned with defining and evaluating expertise in complex domains where there may be no agreed-upon expertise levels, no single right answers to problems, and where the observation and measurement of real-world expert performance is difficult. This paper reports the results of an experiment in which expertise was assessed in an extremely complex and demanding domain -- military command decision making in tactical warfare. The hypotheses of the experiment were: 1) command decision-making expertise can be recognized in practice by domain experts; 2) differences in the command decision-making expertise of individuals can be identified even under conditions that do not fully replicate the real world; and 3) observers who are not domain experts can recognize the expert behaviors predicted by a mental-model theory about the nature of expertise. In the experiment, the expertise of military officers in developing tactical plans was assessed independently by three "super-expert" judges, and these expertise-level ratings were correlated with independent theory-based measures used by observers who were not domain experts. The results suggest that experts in a domain have a shared underlying concept of expertise in that domain even if they cannot articulate that concept, that this expertise can be elicited and measured in situations that do not completely mimic the real world, and that expertise measures based on a mental-model theory can be used effectively by observers who are not experts in the domain.
    Design and Usability Evaluation of Work Control Documentation BIBA 1156-1160
      Swapnesh C. Patel; Colin G. Drury; Prasad Prabhu
    The present study develops a methodology for design and usability evaluation of work control documentation for aircraft inspection based on the application of human factors research in the areas of information design and aircraft inspection. A taxonomy for design of usable documentation was developed using four basic categories: Information Readability; Information Content; Information Organization; and Physical Handling and Environmental Factors. Within the framework of this taxonomy the existing work control documentation for two extreme representative conditions of aircraft inspection tasks, the A-check and the C-check was evaluated for usability. Issues for workcard redesign were identified within this taxonomy using data from usability evaluation and these were then formulated into a set of 49 guidelines for design. These guidelines were then used to develop alternate design solutions offering improved usability. The increase in usability of the redesigned documentation was measured in an on-site empirical evaluation and proved significant. This methodology is currently being extended to the design of usable information for the design and evaluation of portable computer based documentation for aircraft inspection tasks.
    Perceived Fairness of Drug Screening and Performance Testing as Methods for Detecting Performance Impairment BIBA 1161-1164
      Bernadette M. Racicot; Michele Cash; Michael J. Kalsher
    Drug abuse is prevalent and impacts all aspects of society, including the workplace. Testing for impairment due to alcohol or other drug use has become commonplace in organizational settings. Despite potential problems with accuracy, the most commonly used method of screening is urinalysis. As drug testing becomes more common, concern over employees' rights to privacy and fairness of drug testing has also increased. Performance testing has been proposed as a solution to the problems associated with urinalysis, for jobs where eye-hand coordination is critical to job performance. Performance testing is based on the compensatory tracking task and involves correcting for the unpredictable movement of a visual stimulus on a computer screen. Although research suggests that urinalysis testing is perceived as fair in some situations (e.g., where need is high such as in safety-sensitive jobs), no research has been conducted which examines the perceived fairness of performance testing.
       The purpose of the current research was to examine the effects of type of testing (urinalysis versus performance testing) and need for testing (high versus low accident history) on perceived fairness and invasion of privacy. In addition, the effects of fairness and invasiveness on the willingness to apply for a job in the company and acceptance of the screening policy was examined.
       One-hundred adults participated in the study. Results indicated that urinalysis screening was perceived as more fair than performance testing. No effects of need (accident rate) were obtained for either fairness or invasion of privacy. Multiple regression analysis indicated that both fairness perceptions and invasion of privacy predicted willingness to apply for a job and acceptance of the policy. Implications of the results and suggestions for future research are discussed.

    TEST AND EVALUATION: Panel

    Verification and Validation of Complex Systems: Human Factors Issues BIBA 1165-1169
      John A. Wise; V. David Hopkin; Richard S. Gibson; Paul Stager; William F. Stubler
    The issue of verifying and validating complex systems based on human factors criteria is becoming widely recognized. The need has become particularity significant with the development on the highly automated systems currently being developed for the new air traffic control systems around the world. This panel discusses several issues that have evolved from an international working meeting on the topic.

    TEST AND EVALUATION: The Measurement and Evaluation of Collective Unit Training and Performance

    The Measurement and Evaluation of Collective Unit Training and Performance BIBA 1170
      Richard E. Christ; Frederick A. Muckler
    Recent reviews of team training and team performance have drawn at least one common conclusion: Much more research needs to be conducted on the process of and methods for measuring and evaluating teamwork. The current absence of reliable, valid, and robust measures of teamwork hinders not only the development of optimal collective training strategies, but also team-oriented research, human resource management efforts, and organizational and systems development programs.
       The objectives of this symposium are to (a) present an overview of some key theoretical and methodological issues which confront researchers and practitioners concerned with teamwork, and (b) introduce several innovative concepts, methods, and procedures which can aid in solving some of the problems associated with the measurement and evaluation of teamwork.
       These objectives will be met, in part, through presentations which describe and discuss (a) a conceptual framework for analyzing and interpreting measures of collective behavior, (b) the application of complexity theory-based measures to team and organizational performance, (c) a measure of teamwork based on the confidence team members have in their individual and collective capabilities, and (d) a system which supports the measurement and evaluation of unit collective performance in a simulation network environment. (The essence of these presentations are captured in the four papers which follow this abstract.) The discussant will provide his summary of the key issues addressed, as well as some that were not addresses. Finally, inputs and active participation of the audience will be solicited.
       The desired impact of this symposium is a heightened awareness and appreciation of the need for more research on teamwork measurement methods and procedures. The long-term goal of the symposium is to stimulate that research.
    Toward a Conceptual Model for Measurement and Evaluation of Tactical Performance of GNUTs: Groups, Networks, Units, and Teams BIBA 1171-1175
      John A. Modrick
    The objective of performance measurement is to assess the operational effectiveness of an individual or unit: use of resources to accomplish operational objectives. A continuum of collectives from groups to teams on the basis of organizational attributes is proposed. A shared plan of operation is proposed as the organizing agent of collective performance. Tactical decision making is defined in the context of adaptive problem solving. Although decisions are implemented as procedures, the procedures must be improvised in the situation and adapted to local conditions. Tactical Procedure Scripts are proposed as a structure for organizing performance data into operationally meaning segments for analysis, evaluation, and after action review. Operational and functional processes of GNUTS are differentiated and a three level process model is outlined. A domain model for tactical decision making and the use of behavioral objectives in a test plan are discussed.
    Considerations in the Application of Complexity Theory-Based Measures of Individual Performance to Team and Organizational Tasks BIBA 1176-1180
      Robert W. Swezey
    The development of techniques for measuring complex task performance continues to be a problem area both in government and industrial contexts. This problem becomes even more critical as emphasis moves from individual, to group and/or team performance. This paper suggests a variety of measurement techniques that have been applied to the assessment of individual complex performance, and comments on the use of these (and similar) techniques with respect to the measurement of team performance. The measures are derived from the study of "Complexity Theory" (cf. Streufert and Swezey, 1986), and include consideration of both strategic and general planning activity, as well as the diversity of action required in complex team performance situations.
    A Confident Measure of Teamwork: The Efficacy of Confidence Assessment and Feedback Enhancement for Collective Training BIBA 1181-1185
      Kenneth J. McKeever; Richard E. Christ
    The perceptions that team members have of each other's capabilities and the accuracy of those perceptions are very important in determining how well a team will perform. This paper describes a method for assessing, and the consequences of, team members' confidence in the capabilities of their peers. The mutual judgments of confidence are derived from knowledge each team member has of the capabilities of others to perform their respective tasks and to coordinate their actions with those of other team members. Implications of the accuracy of this knowledge and its impact on collective team training and performance are discussed.
    Measuring the Performance of Armor Platoons in the SIMNET Environment BIBA 1186-1190
      Larry L. Meliza
    The Unit Performance Assessment System (UPAS) was developed to support collective performance measurement in the simulation networking (SIMNET) environment. The UPAS collects network data and integrates these data with data on unit plans, terrain features, and communications to provide a more complete picture of performance than is possible with network data alone. This paper illustrates how UPAS data displays can be used to assess the performance of units in accordance with standards from the U.S. Army Mission Training Plan document for tank platoons.

    TEST AND EVALUATION: T&E in Systems Evaluation

    Real-Time Simulation of Multiple Parallel Approaches BIBA 1191-1195
      Eric C. Neiderman
    This paper describes an ongoing program of real-time, interactive air traffic control simulations to test and evaluate the feasibility of conducting closely-spaced, independent, instrument approaches to dual, triple, and quadruple parallel runways. Real-time simulations are used to test and evaluate the human, technological, and systemic issues critical to the implementation of independent multiple parallel approaches. These simulations quantitatively evaluate controller performance, pilot/aircraft performance, and airport capacity issues. Simulation data are also used in the assessment of risk associated with the operation. To address human capabilities and limitations, qualitative analyses are used to assess the opinions of controllers, flight crew members, simulation technical observers, and recognized subject matter experts. This paper describes the planning, implementation, data collection, analysis, and related issues involved in real-time simulation for the development of national standards for independent multiple parallel approaches.
    A Comparison of Test Methodologies for Air Traffic Control Systems BIBA 1196-1200
      Mark A. Guidi; Michele Merkle
    The Federal Aviation Administration (FAA) is currently involved in a tremendous effort to upgrade the nation's Air Traffic Control (ATC) system. Included in this effort is a new communications system called the Voice Switching and Control System (VSCS) for use primarily in the Air Route Traffic Control Centers (ARTCCs). The critical nature of the communications system, the complex Computer Human Interface (CHI) and functionality, and technology differences from the existing communications system caused the FAA to involve an Air Traffic Controller user group early in the design process. This group of subject matter experts was intended to help ensure adequate operational testing which would help secure user acceptance when VSCS was fielded. This paper discusses the methodology developed for the operational evaluation of the prototype VSCS in the Design Competition Phase (DCP) of the program. The methodology exposed problems in the areas of specification compliance, system stability, voice quality, CHI and operational suitability beyond those identified by the formal development test program called Factory Acceptance Testing (FAT). It was discovered that individual system functions that worked properly when exercised in isolation during FAT did not always work properly when exercised in realistic operational scenarios by controllers. The comparison of results between FAT and the operational evaluations show that controller evaluations should be included throughout the development process of FAA programs, and that the methodology used plays a fundamental role in uncovering issues.
    Procedures and Metrics for Aircraft Cockpit Display Evaluations BIBA 1201-1205
      Lisa F. Weinstein; William R. Ercoline
    The standardization of test methods for the evaluation of aircraft cockpit displays is an area display designers need to investigate. Comparable simulation facilities, and experimental protocols including tasks, performance parameters, data analysis techniques, and subject pools, need to be employed across military and civilian research laboratories to ensure that the results of simulation efforts will be interpreted similarly by all researchers and designers. This paper reviews the types of tasks and data collection, reduction, and analysis techniques used by researchers during a five-year Air Force research program designed to: 1) develop a standard head-up display (HUD) symbology set for use as a primary flight reference during instrument flight, and 2) develop a standard symbology set to be used as a baseline for comparing other HUDs. The program objective was met. The symbology set will be included in a revision of Military Standard (MIL STD) 1787, Aircraft Display Symbology.
    Testing and Evaluation of Cockpit Decision Aiding Systems: Issues and a Case Study BIB --
      Patricia A. Casper

    TRAINING: Training Interventions for Complex Skills

    Strategies and Automaticity: Implications for Part-Task Training BIBA 1206-1210
      David L. Strayer; Arthur F. Kramer
    This research examined the role of strategic and automatic processing in the acquisition of cognitive skill. These factors were dissociated by manipulating the predictability of Consistently Mapped (CM) and Variably Mapped (VM) stimuli in a memory search task. In blocked CM and VM conditions, subjects could choose different strategies for each condition. However, in mixed CM and VM conditions, the subjects had no basis for choosing differential strategies. Subjects who received mixed training exhibited less skilled performance than subjects who received blocked training. Moreover, transfer conditions revealed what appears to be a critical interval for learning to use differential strategies. The implications for part-task training are discussed.
    Automation and Supervisory Control: A Perspective on Human Performance, Training, and Performance Aiding BIBA 1211-1215
      John M. Lockhart; Michael H. Strub; John K. Hawley; Lourdes A. Tapia
    This paper is based on results from an on-going effort sponsored by the US Army Research Institute (ARI) concerned with human performance and training issues in automated, near-real-time air defense command and control systems. Air defense command and control is the specific applications context, but the paper's implications extend to many contemporary process control settings. Topics that are addressed in the paper include: (1) human performance problems associated with automation, (2) a new look at human performance requirements in near-real-time process control, (3) and training and job performance support requirements for supervisory controllers. The "new look" portion describes a reasonable and evolving concept for human participation in automated processing, designated Rule-Based Supervisory Control. The paper is intended to introduce these topics to concept developers, system designers, and trainers dealing with automated process control technology.
    Combining a Multiple Emphasis on Components Protocol with Small Group Protocols for Training Complex Skills BIBA 1216-1220
      Wayne L. Shebilske; Jeffrey A. Jordan; Winfred, Jr. Arthur; J. Wesley Regian
    An Active Interlocked Modeling (AIM) Dyadic protocol for training complex skills, an AIM Tetradic protocol, and an Individual Control protocol were tested alone and in combination with a Multiple Emphasis on Components (MEC) protocol creating 6 conditions for training a complex computer game. We randomly assigned 120 paid subjects to the six conditions. Total game score improved over 10-1 hr sessions for all conditions. Improvement rate replicated advantages previously reported for AIM Dyad, AIM Tetrad, and MEC over the Individual Control. The AIM Dyad with MEC was better than either the AIM Dyad or the Individual with MEC. The AIM Tetrad with MEC was worse than either the AIM Tetrad or the Individual with MEC. Similar patterns occurred on retention, transfer, and resistance to secondary task interference. We discuss implications for acquiring and automatizing attention control strategies through observational learning.
    An Examination of Two Ergonomically Designed Performance Aids BIBA 1221-1225
      Mark E. Barnes
    The purpose of the present study was to examine the effects of providing two simple tactical aids designed to bolster cognitive ability while problem-solving. After receiving computer-based instruction, subjects used either an orientation aid, a short-term memory aid, both aids, or no aids to perform a computer-based electronic problem-solving task. A major goal was to determine whether the effect of each aid on performance conformed to either a compensatory model or a training model. Results were mixed. That is, some evidence supported the compensatory interpretation, while other evidence supported the training model interpretation. Specifically, an interaction between short-term memory scores and use of the short-term memory aid showed that the aid helped low scoring subjects solve problems quicker when they used the aid more. However, most of the evidence suggested that, in terms of the time needed to solve problems, the effects of both aids were characteristic of a training model.

    TRAINING: Training for Team Coordination and Decision-Making Effectiveness: Theory, Practice, and Research Directions

    Training for Team Coordination and Decision-Making Effectiveness: Theory, Practice, and Research Directions BIBA 1226-1227
      Catherine E. Volpe
    There is no question that issues surrounding effective, coordinated team performance are considered topics of vital importance in today's organizations (Salas, Dickinson, Converse & Tannenbaum, 1992). This is particularly true for teams that must operate in stressful, unpredictable circumstances. Indeed, the increasing complexity of the workplace has created a dependence on teams who must often perform under stressful conditions (e.g., aircrews, firefighters, surgical teams).
       The effectiveness of such teams depends on the coordinated and cooperative activity of the individuals who comprise them. These individuals must often operate under hazardous conditions characterized by heavy workload and time pressure. Research has shown that these stressors severely restrict the ability of team members to communicate with each other. In effect, reducing the ability of the team to coordinate effectively (Kohn, Kleinman, & Serfaty, 1987).
    Adaptation to Stress in Team Decision-Making and Coordination BIBA 1228-1232
      Daniel Serfaty; Eliot E. Entin; Catherine Volpe
    Teams with records of superior performance have one common critical characteristic: they are extremely adaptive to varying task demands. These teams were observed to switch between several different coordination strategies and organizational structures, with different lines of authority, communication patterns, and task responsibilities, as they move between normal operations and high-tempo or emergency situations. Two questions are central to the issue: What are the effects of external stressors on team performance, and what are the mechanisms by which teams of decision-makers cope with stress? Our main hypothesis is that team coordination strategies evolve from explicit coordination under low workload conditions to implicit coordination as workload increases. To illustrate these ideas, this paper presents findings from an experimental study on the effects of stress on the performance of command teams. The computer-based experimental task simulates operations in a naval environment in which a hierarchical team of four decision-makers must coordinate complex and ambiguous information to make identifications on air targets. Three task-related stressors -- time-pressure, uncertainty, and ambiguity, -- and one information-structural variable were manipulated in a within-subject, full-factorial design. Results show some complex patters of the way the different stressors combine to generate stress and affect the team decision and coordination strategies. Implicit coordination patterns, anticipatory behavior, and redirection of the team communication strategy are evident under conditions of increased time-pressure. Discrepancy between the subordinates' and the team leader's mental model of the costs of errors generates non-trivial patterns of error-making in the teams. The team leader's periodic update had a stabilizing effect on the team communication strategy. Different implementations of team training interventions to enhance mutual anticipation, prevent inadequate adaptation to stress, and foster implicit coordination in command teams are proposed.
    Effects of Workload on Communication Processes in Decision Making Teams: An Empirical Study with Implications for Training BIBA 1233-1237
      Julie M. Urban; Clint A. Bowers; Susan D. Monday; Ben B., Jr. Morgan
    Recent empirical studies of decision making in teams demonstrate that team structure and workload significantly influence team performance. In many operational environments, however, it is impossible to change these factors, even as a mechanism for enhancing team performance. Therefore, it is necessary to create training interventions that will optimize performance within existing team structures and workload levels. Several studies suggest that team processes are the most likely target for this type of intervention. The current investigation sought to develop a laboratory analogue of a common team structure (i.e., the "product team") and to assess the effects of high and low workload on team performance processes within this structure. The results suggest that different communication behaviors facilitate effective performance under low and high workload.
    The Role of Planning in Coordinated Team Decision Making: Implications for Training BIBA 1238-1242
      Rene'e Stout; Eduardo Salas
    Critical decisions are made every day by teams of individuals who must coordinate their activities to achieve effectiveness. Recently, researchers have suggested that shared mental models among team members may help them to make successful decisions. Several avenues for training shared mental models in teams exist, one of which is training in planning behaviors. The relationship between team planning, team shared mental models, and coordinated team decision making and performance is explored.
    Cross-Training Highly Interdependent Teams: Effects on Team Processes and Team Performance BIBA 1243-1247
      Kimberly K. Travillian; Catherine E. Volpe; Janis A. Cannon-Bowers; Eduardo Salas
    Understanding teams and team functioning is more important today than ever before. Recent economic conditions and technological developments have made team work increasingly critical in a wide array of settings. This increased level of dependence on the team as an operative unit brings new insight and in turn new questions, regarding the internal mechanisms and operational effectiveness of the team. In particular, how and why do different types of teams function differently and what kind of training is best suited for what type of teams?
       To a large extent, the nature of a team and its degree of role-related interdependence may regulate the amount of interactional requirements, knowledge, and therefore training, necessary for each member to perform optimally. Specifically, as team member roles become more highly interdependent, the level of each member's knowledge about his fellow team mates' roles becomes increasingly important. This knowledge becomes even more critical under stressful, fast-paced conditions. Although little attention has been given to workload in conjunction with team processes or team performance, early teamwork studies demonstrate that communication and overall performance decline as workload is increased (Briggs & Johnson, 1967; Hemphill & Rush, 1952).

    TRAINING: Panel

    Issues in Providing Effective Training for Large Groups BIBA 1248-1251
      Franklin L. Moses; Earl A. Alluisi; Herbert Bell; Paul J. Sticha; Angelo Mirabella; Valerie Gawron; Gary Klein
    The design of training for large groups or collectives demands a focus on group performance that differs from a mere aggregation of individual, crew, and smaller team performances. Emphasis on the training of large groups has broad military and non-military applicability, especially where success depends on complex interactions and multiple subgoals. Five panelists describe and discuss training system design factors and "lessons learned" as they relate to issues in training large groups. The session features a discussant with extensive experience in training research and development, and includes interactions between the discussant, the panel, and the audience.

    TRAINING: Training Issues in Aviation

    Methods for Correlating Visual Scene Elements with Simulator Sickness Incidence BIBA 1252-1256
      Robert S. Kennedy; Kevin S. Berbaum; Martin G. Smith
    Simulator sickness occurs in a large number of Army, Navy, and Marine Corps simulators, and is most prevalent in moving-base, rotary-wing devices which employ cathode ray tube (CRT) video displays as opposed to fixed-wing, dome-display trainers with no motion base. Based on data from a factor analysis of over 1000 Navy and Marine Corps pilot simulation exposures, a new scoring procedure was applied to two helicopter simulators with similar rates of simulator sickness incidence. Based on the factor analytic scoring key, the two simulators showed slightly different sickness profiles. Preliminary work was begun to record the visual scene by video frame-by-frame decomposition and automated scoring algorithms were developed. The findings are discussed from the standpoints of (1) recommendations for future design and use of simulators, and (2) the metric advantages and other merits of the "field experiment" methodology to address human factors problems with simulator sickness.
    Analysis of Skill on a Flight Simulator: Implications for Training BIBA 1257-1261
      Barry P. Goettl
    A backward transfer technique was used to identify component skills related to performance on a PC based flight simulator. Forty subjects were first trained on the simulator for eight hours and were then tested on several component skills tasks (backward transfer). A second group of 40 subjects was first given the component skills tasks and then was trained on the simulator task (forward transfer). Both groups were then divided into high- and low-ability groups based on whole-task performance and were compared on the component tasks. Backward transfer subjects showing proficiency on the simulator also showed proficiency on tasks related to pitch, altitude, and heading control, and tasks related to spatial orientation skills. Analysis of the forward transfer group suggested that many of the ability differences observed after whole-task training may have existed prior to whole-task training. Furthermore, some ability differences obtained for the forward transfer group were not obtained in the backward transfer group suggesting that these skills may be acquired through whole-task training. The implications of these results are discussed in the context of part-task training, adaptive training, and gender differences.
    Impact of Task Difficulty on the Acquisition of Aircrew Coordination Skills BIBA 1262-1266
      Curt C. Braun; Clint A. Bowers; Barbara E. Holmes; Eduardo Salas
    The skills approach to aircrew coordination focuses on the training of specific coordination behavior. While this approach has shown promise, careful consideration must be given to the manner in which these skills are trained. A growing body of literature suggests that training workload impacts the acquisition of skills. The present study examined the effectiveness of two training paradigms on the development of aircrew coordination. One regimen of training was characterized by consistent levels of task difficulty over a series of training sessions. The other regimen involved incrementally increasing task difficulty over training sessions.
       Twenty IFR rated pilots comprised 10 two-person crews. One-half of the crews (control group) completed nine training flights that were of consistent task difficulty. The remaining half completed nine training flights that increased incrementally in task difficulty: three low, three moderate, and three high task difficulty flights. Following the nine training flights, all crew completed five novel aerial reconnaissance flights during which they were instructed to map buildings within a specified area. Measures of subjective workload, flight performance, and secondary task performance were taken for all flights. An additional measure of building identification was also taken for the five reconnaissance-type flights.
       Measures of subjective workload validated the increasing workload associated with the experimental training regimen. Analysis of the workload data taken during novel task flights failed to reveal differences between training groups. Moreover, there were no significant differences in flight performance between groups. Measures of building identification, a task heavily dependent on crew coordination, revealed significant differences between groups. Experimental crews identified significantly more buildings than their control counterparts for two of the five flights. Implications for aircrew coordination training are discussed.
    Training for Decision Making in Aircraft Inspection BIBA 1267-1271
      Anand K. Gramopadhye; Colin G. Drury; Joseph Sharit
    Research on civil aircraft inspection and maintenance has shown the potential for employing human factor interventions in improving performance. A series of training experiments was developed to understand the effects of different training interventions in the visual inspection domain. This paper reports on preliminary results obtained in applying a combined active and progressive part training scheme in improving the decision making performance for a visual inspection task. The task was a computer simulated airframe visual inspection task.

    TRAINING: Issues in Training Problem Solvers

    Transfer of Training in a Fault Diagnosis Task BIBA 1272-1276
      Charles T. Dammon; David M. Lane
    Two experiments on the learning and transfer of the hypothesis testing strategy of testing easy-to-test hypotheses first were conducted. The first experiment found that this strategy could be discovered and used in a very simple fault diagnosis task but not in a slightly more complicated task. Subjects who learned the strategy in the simple task were able to transfer it to the more complicated task. The second experiment showed far transfer: The learning of this principle of hypothesis testing transferred to a task sharing no surface features with the training task. It is concluded that it is worthwhile to train people on the use of fault diagnosis strategies.
    Einstellung: Knowledge of the Phenomenon Facilitates Problem Solving BIBA 1277-1280
      David M. Lane; Dean G. Jensen
    If subjects are given a series of problems that all have the same type of solution, they often have great difficulty with a subsequent problem that would ordinarily be solved very easily. This phenomenon is referred to as psychic blindness or Einstellung. This study explored whether knowledge of the Einstellung phenomenon facilitates problem solving. Eight subjects in each of three experimental conditions were given set-inducing problems followed by an otherwise easy "critical" problem that could not be solved by the strategy used on the set-inducing problems. Subjects in one condition worked on the easy problem without interruption. Subjects in a second condition were interrupted by an unexpected event. Subjects in a third condition were interrupted by a message explaining how the ability to solve an otherwise easy problem could be inhibited after solving a series of problems with more difficult solutions. Subjects given this hint were three times more likely to solve the easy problem than were subjects in the other experimental conditions. Four subjects in the No-Set Control condition all solved the easy problem by the third trial. The implications for training electronics technicians, computer programmers and other problem solvers are discussed.
    An Approach to Identifying Meaningful Action Patterns in Student-Tutor Interactions BIBA 1281-1285
      Anna L. Rowe; Nancy J. Cooke
    Part of the success of computerized intelligent tutoring systems will be associated with their ability to assess and diagnose students' knowledge in order to direct pedagogical interventions. What is needed is a methodology for identifying general relationships between on-line action patterns and patterns of knowledge derived off-line. Such a methodology would allow an assessment and diagnosis of knowledge, based only on student actions. The focus of this initial research is the development of a means of identifying meaningful action patterns in student-tutor interactions. Actions executed by subjects on a set of verbal troubleshooting tests (Nichols et al., 1989) were summarized using the Pathfinder network scaling procedure (Schvaneveldt, 1990). The results obtained from this work indicate that meaningful patterns of actions can be identified using the Pathfinder procedure. The network patterns are meaningful in the sense that they can differentiate high and low performers as defined by a previous scoring method. In addition, the networks reveal differences between high and low performers suggestive of targets for intervention.
    Physics Education in a Virtual Environment BIBA 1286-1290
      John W. Brelsford
    A study is directed at a comparison of Virtual Reality as an educational tool in physics instruction with standard, teacher-organized, or computer-aided learning. Findings generally indicated that virtual reality-based learning is superior to lecture-based control conditions. The dependent variable was a residualized knowledge of physics measure obtained from subjects four weeks following termination of training. As a training method, virtual reality was superior to the control condition at the four-week retention period. Such a finding supports cognitive theorists who argue that the lack of opportunities for hands-on, manipulation of objects in the physical world is one of the reasons children are often poor at intuitive physics. Virtual reality provides them the opportunity to develop manipulational skills they did not previously possess.

    VISUAL PERFORMANCE: Preattentive Processing in Visual Search

    Preattentive Processing in Visual Search BIBA 1291-1294
      Theodore J. Doll
    Visual search is fundamental to many tasks that human operators perform in conjunction with engineered systems. Some obvious examples include industrial inspection, acquisition of information from aviation and weapon systems displays, and interaction with general purpose computer displays. Ease of visual search is a fundamental consideration in the design of computer-based menus and ironic displays (e.g., Andre and Wickens, 1991). Visual search efficiency affects performance variables such as the ease with which an interface or a piece of software can be learned, the time required to complete tasks, and user satisfaction. In weapon systems, visual search affects the probability of target detection, the time until detection, and the range at which detection occurs. These parameters can be critical for combat survival and mission effectiveness.
    Guided Search 2.0: The Upgrade BIBA 1295-1299
      Jeremy M. Wolfe
    This paper provides a brief review of the Guided Search model of human visual search behavior. In the model, parallel processes analyze a limited number of basic visual features across large portions of the visual field. The output of these processes can be used to guide attention in the deployment of the limited-capacity processes that are capable of identifying more complex visual targets.
    Highlighting with Flicker: Some Basic Visual Search Considerations BIBA 1300-1304
      Karl F. Van Orden; Joseph DiVita
    Previous research has demonstrated that search times are reduced when flicker is used to highlight color coded symbols, but that flicker is not distracting when subjects must search for non-highlighted symbols. This prompted an examination of flicker and other stimulus dimensions in a conjunctive search paradigm. In all experiments, at least 15 subjects completed a minimum of 330 trials in which they indicated the presence or absence of target stimuli on a CRT display that contained either 8, 16 or 32 items. In Experiment 1, subjects searched for blue-steady or red-flickering (5.6 Hz) circular targets among blue-flickering and red-steady distractors. Blue-steady targets produced a more efficient search rate (11.6 msec/item) than red-flickering targets (19.3 msec/item). In Experiment 2, a conjunction of flicker and size (large and small filled circles) yielded the opposite results; the search performance for large-flickering targets was unequivocally parallel. In Experiment 3, conjunctions of form and flicker yielded highly serial search performance. The findings are consistent with the response properties of parvo and magnocellular channels of the early visual system, and suggest that search is most efficient when one of these channels can be filtered completely.
    Eye Movements in Search and Target Acquisition BIBA 1305-1309
      Deborah P. Birkmire; Robert Karsh; B. Diane Barnette; Ramakrishna Pillalamarri; Samantha DiBastiani
    The frequency distribution of eye fixations and fixation durations during a search and target acquisition task was examined to determine if the allocation of visual attention was related to target, scene, and/or observer characteristics. Ninety computer-generated scenes simulating infrared imagery and containing different levels of clutter and zero, one, two, or three targets were produced. Targets were embedded in these scenes counterbalancing for range and position. Global and local clutter were measured using both statistical variance and probability of edge metrics. Thirty-three aviators, tankers, and infantry soldiers were shown still video images of the 90 scenes and were instructed to search for targets. Results of multiple regression analyses of global clutter, local clutter, range, number of targets, target dimensions, target complexity, and group membership on eye fixations and fixation durations are given and discussed in terms of search strategies.
    Simulation of Human Visual Search in Cluttered Backgrounds BIBA 1310-1314
      Theodore J. Doll; Shane W. McWhorter; David E. Schmieder
    Work in progress at Georgia Tech to develop a model of human pattern perception, visual search, and detection is reviewed. The model's algorithms are based on research on low-level visual processes. Recent advances in that field have led to the development of computational models of the image processing performed by the visual system from the cornea to the striate cortex. The model also incorporates recent advances from research on visual search. The organization of the model is described, and the results of some preliminary tests are presented.

    VISUAL PERFORMANCE: Information Processing and Formatting

    Individual Differences in Processing Strategy for a Bargraph Display BIBA 1315-1319
      Julie R. Nowicki; Bruce G. Coury
    The bargraph has been described in several ways: as a separable display, as an integral display, and as a configural display with emergent features. The versatility of the bargraph may be in part due to the support it provides for different individual processing strategies. This research identifies two general types of strategies -- holistic and analytic -- which are developed by individuals to solve a classification problem on the bargraph. Multidimensional scaling (MDS), response times, and verbal reports are used to analyze individual strategies. Individuals who developed holistic strategies produced significantly faster reaction times, and reported simple, efficient strategies, with the emergent feature of bargraph shape as an important dimension. The results indicate that the bargraph provides perceptual features which can support several general types of processing strategy.
    The Role of Feedback in Learning Spatially Incompatible Choice Reaction Tasks: Does It Have One? BIBA 1320-1324
      Addie Dutta; Robert W. Proctor
    Stimulus-response compatibility effects have been shown to persist even after extended practice. In the present study, two experiments were conducted to see if the effects persist when knowledge of results that allows subjects to set performance goals is provided. In the first experiment, summary feedback about mean accuracy and mean reaction time was provided after each block of 40 trials of practice in a two-choice spatial compatibility task. Subjects practiced the task for 2,400 trials, yet the compatibility effect was not eliminated. Compared to previous experiments, reaction times were faster overall, but the degree of change was the same for both compatible and incompatible assignments. In the second experiment, a response deadline was imposed on each trial. If the subject did not respond within the time limit, which was reduced as the experiment progressed, auditory feedback was presented. Summary feedback was also presented as in Experiment 1. Again, 2,400 trials of practice reduced but did not eliminate the compatibility effect. The greater reduction in the difference in reaction times for compatible and incompatible assignments, relative to other experiments, could be attributed to speed-accuracy tradeoff. The results indicate that the persistence of stimulus-response compatibility effects with extended practice is not due to poorer motivation to perform with the incompatible assignment. The results suggest that training will be insufficient to overcome difficulties in performance resulting from spatially incompatible assignments.
    The Effects of Display Code and Its Relation to the Optimal Decision Statistic in Visual Signal Detection BIBA 1325-1329
      DeMaris A. Montgomery; Robert D. Sorkin
    This study examined the effects of display element arrangement on observers' performance in both Yes/No and Four-Alternative-Forced-Choice (4AFC) visual signal detection tasks. Observers were given four independent informational sources whose values were drawn from either a signal or noise distribution, depending on the task and type of trial. The information was displayed graphically in one of six formats constructed from a combination of two factors: 1) whether the display elements were arranged to produce an emergent feature, and 2) whether or not the magnitude of the emergent feature was monotonically related to the optimal decision statistic (for the Yes/No task). Arranging the line graph displays to produce an emergent feature improved Yes/No performance and impaired 4AFC performance. Due to the highly efficient performance produced by the angular element code, it was not possible to determine whether visual signal detection was affected by the relationship between the emergent feature and the optimal decision statistic.
    Comparison of Eight Color and Gray Scales for Displaying Continuous 2D Data BIBA 1330-1334
      David H. Merwin; Christopher D. Wickens
    The use of various dimensions of color to encode continuous data has become commonplace with the advent of sophisticated computing hardware and software. Applications users can choose from a variety of color pallets as well as create their own for viewing digitized data sets. A primary HCI question emerging from this expanded availability of color for data display is how best to map color dimensions to data dimensions for various applications. The current study examined a subset of the perceptual/cognitive processes underlying pattern recognition tasks, whose efficacy could be affected by the nature the color scale used to visualize the data being viewed. Three types of observers' judgments were examined: absolute discrimination of a value; relative judgment of the difference between two values; and a rank order judgment of 4 values. These values were expressed in the color of a specific region in images displayed using eight different color and gray scales. Preference ratings were collected for the color scales. Grey scales were best for rank ordering tasks, while a blue-green-yellow scale proved superior for an absolute independent task. Scale preferences did not necessarily agree with performance. Implications of the findings and future research are discussed.

    VISUAL PERFORMANCE: Visual Performance Using HUDS and HMDS

    Requirements for HUD Raster Image Modulation in Daylight BIBA 1335-1339
      Charles J. C. Lloyd; William F. Reinhart
    Head-up displays (HUDs) represent the leading candidate display technology for inclusion in an enhanced or synthetic vision system (EVS or SVS) for commercial transport aircraft. One common EVS concept assumes the raster display of raw or processed sensor (radar or IR) data. However, experience with the use of raster rather than stroke display modes has been largely limited to the presentation of images captured by IR sensitive and image-intensified cameras during night flying conditions when the luminance of the forward scene over which the image will be superimposed is much lower than in daytime. The objective of this work is to generate a specification for minimum HUD raster image modulation assuming real-world luminance values typically found in low-visibility, daylight flight. Six Honeywell pilots rated the image quality and utility of flight video as presented through a military-style HUD in a transport cockpit mockup. Flight video came from daylight FLIR and daylight CCD cameras. The luminance of the forward scene against which the HUD image was superimposed was varied among nine levels ranging from 5 fL to 10,000 fL. The results indicate that HUD raster luminance must be approximately 50% external scene luminance to promote good pilot awareness of general terrain. To maintain good utility and visibility of standard, high-contrast runway markings, runway center line, and runway edges, HUD raster luminance must be approximately 15% of the forward scene luminance.
    Attentional Effects with Superimposed Symbology: Implications for Head-Up Displays (HUD) BIBA 1340-1344
      David C. Foyle; Robert S. McCann; Beverly D. Sanford; Martin F. J. Schwirzke
    Previous research has shown that the presence of head-up display (HUD) symbology containing altitude information improves altitude performance at the cost of terrain path performance, implying that these information sources may not be available for concurrent cognitive processing. In two flight simulation experiments, the influence of attentive field size on this concurrent processing limitation was evaluated. In Experiment 1, a superimposed digital altitude (i.e., HUD) indicator was presented at three distances from a flight-relevant ground track. A control condition eliminated the digital altitude indicator. Altitude symbology improved performance on the altitude maintenance task, but impaired performance on the ground track task only when directly superimposed. Experiment 2 tested a visual masking explanation of the performance trade-off. Irrelevant HUD information yielded identical results to the HUD absent condition, ruling out effects of visual masking. An explanation in which visual/spatial attention cannot be directed to both HUD information and terrain information simultaneously is proposed. The absence of a performance tradeoff when the HUD and the terrain information are not directly superimposed is attributed to a breaking of attentional tunneling on the HUD, possibly due to eye movements.
    Modeling Attentional Effects with Head-Up Displays BIBA 1345-1349
      Robert S. McCann; Jeannie Lynch; David C. Foyle; James C. Johnston
    Previous research (McCann, Foyle, & Johnston, 1993) has shown that in a simulated approach to a runway, performance of a choice reaction time task is faster when all relevant information is available on the HUD or in the world, compared to when information has to be acquired from both domains. The present experiment tested two attentional models of these results: attention switching and attention sharing. Removing differential motion cues from the display, so that both the HUD and the world were motionless, attenuated the domain effect. The attenuated difference reflected both slower responses on within-domain trials and faster responses on between-domain trials. We conclude that performance with Head-Up Displays is affected by both attention switching and the degree to which attention is shared between domains.
    Effect of Head-Slaved Visual Image Roll on Spatial Situation Awareness BIBA 1350-1354
      Bernard D. Adelstein; Stephen R. Ellis
    We examined whether the inclusion of a third head-slaved "roll" degree of freedom (dof) -- in addition to pitch and yaw dofs -- to control the orientation of a remotely-viewed or computer-synthesized scene can enhance spatial situation awareness. Six subjects were required to match the position and orientation of stationary target markers on a remote taskboard by manually placing response markers on an identical local taskboard. Subjects could only view the remote taskboard through images transmitted to a head mounted display (HMD) from a motorized pitch-yaw-roll camera platform; they could see neither the local taskboard nor their own limbs. Results show that, while systematic overshoot errors in azimuth judgment occurred regardless of the roll condition, the addition of the roll dof to the platform had no statistically discernible effect on the subjects' ability to match the position (i.e., azimuth and elevation) of the remote targets. Absence of the roll dof, however, did affect the subjects' judgment of target orientation when their heads were at maximum elevation (pitch) and azimuth (yaw) combinations.

    VISUAL PERFORMANCE: Visual Psychophysics and Methods

    Effects of Contrast on Perceived Size of Visual Patterns: Theory, Data, and Implications BIBA 1355-1359
      B. Arthur Kirkland; Elizabeth Thorpe Davis; Dean Yager; Troy Surdick; Allison Hochstein
    The perceived spatial frequency of a visual pattern can vary with changes in contrast. Because size is inversely related to spatial frequency and because perceived size is an important distance cue, this has implications for task performance in a variable contrast environment. These environments are common in everyday situations, such as driving in the fog, and in the use of night vision devices. Understanding the underlying visual mechanisms of this effect would help us design systems that compensate for the effect. This understanding also could further develop models of the human low-level visual processes. However, most testing of perceived size and contrast has been done at relatively high contrast levels. This research is conducted at contrast levels near detection threshold. This range allows a more thorough testing of different models of contrast detection. We tested two versions of a multiple spatial-frequency channels model of contrast perception. One model assumes a single set of channels functioning throughout the dynamic range of contrasts used here, the other assumes two sets of channels based on the parvo and magnocellular systems. Our results support the hypothesis that there is a single set of channels at work in the contrast range tested.
    Some Limitations on the Use of the Forced-Choice Technique for Target Detection Research BIBA 1360-1364
      W. Ronald Salafia; Dino A. DaRos
    The forced-choice (FC) format is used for stimulus presentation and performance assessment in a variety of tasks, including target detection and acquisition, tasks that involve primarily vigilance, monitoring, and search (VMS) behaviors. Laboratory experiments, comparison investigations, and system performance assessments have been reported in the literature with numerous claims about FC procedures, including that they lead to simplification of data handling and increased cost-effectiveness. The present report takes issue with these and other claims, as well as with the underlying assumption that FC procedures are interchangeable with continuous-search procedures, when applied to VMS tasks.
    Development of a Microcomputer Based Battery of Temporal Factors Tests BIBA 1365-1369
      R. S. Kennedy; A. D. Ritter; K. S. Berbaum; M. G. Smith
    Our industrialized society places a premium on the ability to resolve visually fine-spatial detail in the environment. But the perceptual demands of new display systems may involve temporal acuity as much as spatial acuity. Inability to "switch" attention and fixation rapidly from one visual display to another may be a major factor in the "human error" component. We hypothesize that individuals differ in their temporal visual acuity and, if so, then scores on tests which tap this capability would be predictive of productivity on jobs and activities with these demand characteristics. A battery of five temporal factors tests implemented on a portable lap-top microcomputer was administered over several trials to 44 subjects. The tests exhibited satisfactory metric properties (stability, reliability), and did not appear to relate to commonly available global mental abilities. An off-the-shelf portable battery of temporal factors which stabilizes rapidly could have several important applications. First, individual differences in temporal acuity could be employed to improve job productivity to the extent that such abilities are at the basis of certain jobs and activities. Second, since time-course changes were evident with the tests, they can be used to study training implications of these temporal factors. Third, the results could be used to identify temporal aspects of visual displays for advancing understanding in engineering design.
    Eye-Gaze Control of the Computer Interface: Discrimination of Zoom Intent BIBA 1370-1374
      Joseph H. Goldberg; Jack C. Schryver
    An analysis methodology and associated experiment were developed to assess whether definable and repeatable signatures of eye-gaze characteristics are evident, preceding a decision to zoom-in, zoom-out, or not to zoom at a computer interface. This user intent discrimination procedure can have broad application in disability aids and telerobotic control. Eye-gaze was collected from 10 subjects in a controlled experiment, requiring zoom decisions. The eye-gaze data were clustered, then fed into a multiple discriminant analysis (MDA) for optimal definition of heuristics separating the zoom-in, zoom-out, and no-zoom conditions. Confusion matrix analyses showed that a number of variable combinations classified at a statistically significant level, but practical significance was more difficult to establish. Composite contour plots demonstrated the regions in parameter space consistently assigned by the MDA to unique zoom conditions. Peak classification occurred at about 1200-1600 msec. Improvements in the methodology to achieve practical real-time zoom control are considered.

    VISUAL PERFORMANCE: Panel

    Visual Cues for Vehicle Control BIBA 1375-1377
      Mary K. Kaiser; Walter W. Johnson; George J. Andersen; Anthony D. Andre; Martin S. Banks; John M. Flach
    Since Gibson's pioneering work in the 1950s, there has been increasing interest in describing the dynamic visual cues operators extract from the "out-the-window" scene to utilize in vehicular control. Despite this interest, we are still a long way from an adequate understanding of what optical information is utilized, and how the information is integrated into an active control strategy. There are a number of reasons for this apparent shortfalling. First, it is difficult to isolate a candidate optical cue; geometry dictates that several candidate cues will co-vary in any natural scene (e.g., edge rate and flow rate). The experimental isolation of an optical cue often results in visual scenes which are quite unnatural, creating the possibility that strategies used in the experimental setting will not generalize to operational settings. Also, much of the laboratory work has focused on demonstrating people's sensitivity to optical variables, utilizing passive verbal judgments rather than active control paradigms. Whereas the demonstration of sensitivity to an optical cue is a logically necessary step, such a demonstration is not sufficient to verify its utility in an active control task. Further, there is the need for an adequate description of the task demands, allowing a proper mapping between what the controller is trying to achieve and the information available to accomplish the task; no single cue (or set of cues) will be appropriate for all vehicular control tasks. Finally, given the robust and opportunistic nature of the human perceptual system, it is possible that the visual cues used for vehicle control will vary from individual to individual, or even within an individual depending on which cues are available and salient in the control environment. The participants in this panel are well versed in the challenges of studying visually based vehicular control. Their presentations will reflect the lessons learned in this field, as well as insights regarding how current and future research can better realize the promise of this domain.

    VISUAL PERFORMANCE: Attention and Workload

    Attentional Guidance in Visual Attention BIBA 1378-1382
      Steven Todd; Arthur F. Kramer
    Earlier research has shown that a task-irrelevant sudden onset of an object will capture or draw an observer's visual attention to that object's location (e.g., Yantis & Jonides, 1984). In the four experiments reported here, we explore the question of whether task-irrelevant properties other than sudden-onset may capture attention. Our results suggest that a uniquely colored or luminous object, as well as an irrelevant boundary, may indeed capture or guide attention, though apparently to a lesser degree than a sudden onset: it appears that the degree of attentional capture is dependent on the relative salience of the varied, irrelevant dimension. Whereas a sudden onset is very salient, a uniquely colored object, for example, is only salient relative to the other objects within view, both to the degree that it is different in hue from its neighbors and the number of neighbors from which it differs. The relationship of these findings to work in the fields of visual momentum and visual scanning is noted.
    Vigilance: Where Has All the Workload Gone? BIBA 1383-1387
      David A. Sawin; Mark W. Scerbo
    The present study explored whether instructions given to subjects at the outset of a vigilance experiment impact their ratings of frustration and workload. The present task consisted of monitoring a video display terminal (VDT) of uniform color for 30 min. Subjects were asked to respond to occasional 3 ms "flickers" to a different color. Half of the subjects were told to relax by focusing on the display, but to respond to any flickers observed. The remaining subjects were given traditional vigilance instructions emphasizing the importance of detecting as many "critical signals" or flickers as possible. Before and after the vigil, subjects completed the NASA Task Load Index (TLX; Hart and Staveland, 1988) which measured the subjective workload for the vigil. Hits and false alarm data were recorded for each 10 min period within the 30 min vigil. A significant reduction in mean number of hits was observed over the three periods for all subjects. A subsequent analysis showed that perceptual sensitivity also declined significantly over time. Performance, however, was not affected by instruction type. Subjects who received relaxation-emphasis instructions did report significantly lower workload and frustration for the vigil than those receiving detection-emphasis instructions. These results indicate that much of what individuals find unpleasant about participating in vigilance experiments may lie with the expectations outlined in the initial instructions.
    The Rate of Gain of Perceived Workload in Sustained Attention BIBA 1388-1392
      William N. Dember; Joel S. Warm; W. Todd Nelson; Karen G. Simons; Peter A. Hancock; Jonathan P. Gluckman
    Perceived workload was measured via the NASA TLX following a visual vigilance task. Five task durations (10, 20, 30, 40, or 50 min) were combined pictorially with two levels of discrimination difficulty (easy, hard) in a between groups design. Detection probability, computed from the final 10 min of watch in each duration condition, varied inversely with signal salience and declined over time. Overall workload varied directly with salience and increased linearly over time. The temporal growth in perceived workload was independent of signal salience. This result suggests that the rate of gain in workload is based upon general features of the vigilance situation rather than specific psychophysical demands such as signal salience.
    Multimodal Measures of the Energetic Demands of Information Processing in a Suboptimal Environment BIBA 1393-1397
      Arthur M. Ryan; Richard W. Backs
    Twenty-four male volunteers participated in a study in which the feature extraction and response choice information processing stages of a visual memory task and the environment in which the task was performed were manipulated in order to assess the specificity of energetic demands. Ambient auditory noise was a state variable that was predicted to directly affect the energetic mechanism supporting the feature extraction processing stage and to indirectly affect the energetic mechanism supporting the response choice processing stage. Several classes of dependent measures were taken including performance, cardiovascular, pulmonary, and metabolic in order to isolate effects upon energetic mechanisms. The present study did not support the proposition of multiple energetic mechanisms. Instead, the combination of a single variable-capacity energetic resource with a flexible allocation policy to the processing stages was a better fit to the results.