bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Human Factors Aspects of Computer-Aiding Concepts for Air Traffic Controllers
Authors: Whitfield David , Ball Robert G. , Ord Geoffrey
Published: July 2017

This paper sets out the basic philosophy of a developing program of computer-aiding concepts for the controller's decision making. A brief review is given of early work on the computer-assisted approach sequencing (CAAS) concept for a major airport, and the main topic is the interactive conflict resolution (ICR) concept for assisting the en route controller in conflict detection and resolution. ICR is a predictive aid used interactively by the controller; the concept is described in detail. A real-time simulation experiment is reported, in which each of three pairs of controllers acted as an executive/support team in handling traffic samples in a busy sector. Objective records and subjective data suggest the effectiveness and acceptability of ICR. Further research on the controller's activities within, and attitudes toward, computer-based tasks is outlined.
Summarizing Military Information: An Application of Schema Theory
Authors: Geiselman Ralph E. , Samet Michael G.
Published: July 2017

This study was conducted to support the development of guidelines for summarizing tactical intelligence data. Sixteen staff officers were asked to read a description of a tactical scenario and to examine 30 enemy situation data (ESD) messages describing the beginning of an enemy border crossing and attack. Each officer summarized the intelligence in preparation for a briefing, and these summaries were evaluated by five knowledgeable military analysts. Collectively, the evaluators favored summaries presented in conversational style, with hard facts and an interpretation of what the intelligence implied. A more specific two-dimensional outline for summarizing was derived by applying recently refined principles of schema theory to the contents of the summaries judged “good” by the evaluators. It was suggested that these prescriptive norms provide the basis for the development of guidelines for staff officers to enable them to produce more useful and effective intelligence-message summaries.
Review of Relationships Between Steering Wheel Reversal Rate and Driving Task Demand
Authors: Macdonald Wendy A. , Hoffmann Errol R.
Published: July 2017

Previous literature and some new data on the relationship between steering wheel reversal rate (SRR) and driving task demand are discussed in terms of a set of theoretical assumptions proposed by Macdonald and Hoffmann (1978). SRR is generally expected to increase with increasing task demand; however, several recent studies found a significant decrease in SRR. It is argued that whether the relationship is positive or negative depends on the level of task difficulty relative to the driver's capacity to cope with it.
Residential Design for the Aging (For Example, the Bedroom)
Authors: Parsons H. McIlvaine
Published: July 2017

Design requirements for residences for older people can best be examined in a matrix that relates environmental aspects and people aspects. The former include the entire setting, resources, spatial arrangement, communication, appearance, consequation, protection, and ambient conditions. The latter consist of activities, locomotion, social interaction, feelings, perception, motivation, health and safety, learning, and manipulation. A review of published design standards, guidelines, and recommendations about bedrooms in housing for the elderly details what has been specified and demonstrates that much remains to be done.
The Aircraft Landing Test: An Information Processing Approach to Pilot Selection
Authors: Fowler Barry
Published: July 2017

The Aircraft Landing (AL) test is a pilot selection device in which attempts are made at simulated approaches and landings of an aircraft on a runway until a criterion skill level is achieved. The test was designed with principles from the information processing model of skilled performance in mind, and two concepts from the model were tested: hierarchical mechanisms and feedback. Using Canadian Forces pilot trainees, validities up to 0.45 (n=104, no previous flying experience) and 0.49 (n=26, previous flying experience) were obtained against a criterion score based on flying tests at 7 and 12 h in a light aircraft. It was concluded that the practical utility of the test was highly satisfactory and that its validity could be increased by modifications. The pattern of results provided some support for the theoretical predictions from the information processing model, but methodological difficulties prevented a clear-cut interpretation. Advantages of this approach over an abilities model are discussed.
Evaluation of Symbolic Public Information Signs
Authors: Mackett-Stout Janice , Dewar Robert
Published: July 2017

In a series of four experiments, symbolic representations of eight public information messages were evaluated in an attempt to identify the relative adequacy of each symbol Four versions of each message were examined using measures of legibility distance, comprehension, preference, and glance legibility. Significant positive correlations were found among the first three measures. An efficiency index was employed as an overall measure of the effectiveness of individual symbols, and recommendations were made concerning their future use.
Detecting the Unexpected in Photointerpretation
Authors: Biederman Irving , Mezzanotte Robert J. , Rabinowitz Jan C. , Francolini Carl M. , Plude Dana
Published: July 2017

A methodology for measuring photointerpretation performance from a single glance at a novel scene is presented. Subjects attempted to detect the presence or absence of a target. object, specified in advance by the object's name, from a cued position in a 150-ms flash of a line drawing of a real-world scene. The cue, a dot, was presented immediately after the presentation of the scene, so that the subjects were uncertain as to the position of the cued object. Miss rates as a function of distance of the cued position from central fixation, target size, and degree of target camouflage were determined. The experiment also explored how these functions varied with objects that were in unexpected locations, such as a sofa floating in a street scene. Objects in these locations violated the usual constraints which characterize the organization of real-world scenes. Large, uncamouflaged targets in a normal relation to their context suffered only modestly from the effects of increasing distance from fixation. But targets that were small, camouflaged, or undergoing violations of the relational constraints suffered marked increases in miss rates when presented only 3 or 4 deg from central fixation. Since humans can assimilate visual information faster than the eye can move, the maximum rate at which a fixation can be made provides a limit–the saccadic barrier–of visual information processing. In addition to furnishing general guidelines for scene processing displays, the results of this experiment serve to restrict the breaking of the barrier-with the aid of high-speed, high-capacity display systems–to the extraction of the setting or gist of a scene. Individual targets, unless large, uncamouflaged, and in expected locations, require direct fixation.
Visual Monitoring in a Simulated Agricultural Machinery Operation
Authors: Kaminaka M. Stephen , Rehkugler Gerald E. , Gunkel Wesley W.
Published: July 2017

Many agricultural machinery operations involve the monitoring of implements located behind the tractor operator. This visual monitoring task of a tractor operator was simulated in the laboratory. The effects of the type of task (steering only vs. steering plus rear monitoring), the operators' peripheral field of view, and the steering input frequency on operator performance were studied. Response times to visual stimuli located in the visual sphere surrounding the operator were determined. Visual field contours derived from the experimental data were plotted and used to illustrate variations in the operators field of view due to changes in the experimental variables.
Tactile Sensitivity in the One-Atmosphere Diving System JIM
Authors: Curley Michael D. , Bachrach Arthur J.
Published: July 2017

The ability of divers to discriminate differences in weight and shape while working inside the one-atmosphere diving suit JIM was assessed by two experiments. In the first study five male operators each completed four series of discriminations among weights ranging from 5 to 0.5 lbs. (2.3 to 0.2 kg). The operators could discriminate a weight difference of 0.7 kg with 95% accuracy when in JIM, but were unable to exceed chance expectations when the weight difference dropped to 0.2 kg. The second study measured the capability of the JIM operators to identify correctly various objects under conditions of reduced visibility while under water in the JIM suit. The operators were able to identify correctly the object on 15 of 19 trials, primarily relying on tactile cues mediated through hand manipulators.
A Method for Quantifying Control Accessibility
Authors: Banks William W. , Boone Mark P.
Published: July 2017

A method of statistically quantifying the accessibility of controls was proposed and validated. The resulting index of accessibility (Ia) takes into account three sources of variability: operator's reach envelope, frequency of use, and relative physical position of controls with respect to the operator. Operator ratings and measurement (percent of controls reached) were significantly correlated with Ia values, lending support to the notion that Ia is a valid and sensitive measure of control placement.
Problem-Solving Skills of Maintenance Trainees in Diagnosing Faults in Simulated Powerplants
Authors: Hunt Ruston M. , Rouse William B.
Published: July 2017

Eighty-six maintenance trainees in an FAA certificate program participated in two experimental studies of context-free and context-specific problem solving skills. The context-free training method included two previously reported tasks that involve the troubleshooting of graphically displayed networks. The context-specific task involved automobile and aircraft powerplants simulated on a new computer-based system called FAULT (Framework for Aiding the Understanding of Logical Troubleshooting). Results of the study indicated that it is possible to develop context-free diagnostic skills to be used in context-specific problems and that suboptimal diagnostic performance is largely due to not fully utilizing the information present in the structure of the problem.
Computer Commands in Restricted Natural Language: Some Aspects of Memory and Experience
Authors: Scapin Dominique L.
Published: July 2017

In this experiment, two groups of subjects having different levels of experience with computers were tested to compare the learning and recall of computer command definitions that differed in context and redundancy and to study the effect of context change. The results show that inexperienced (naive) subjects have different requirements than do more experienced subjects. The experienced group recalls more meanings than the inexperienced group but is more negatively influenced by the number of competing words (that is, different words used to label the same computer function) than by contextual connotation. For the inexperienced subjects, particularly, it appears that computer-oriented words used as commands are better than more usual words. Besides, inexperienced subjects are more negatively influenced by context changes than are experienced subjects.
An Investigation of Health Complaints and Job Stress in Video Display Operations
Authors: Smith Michael J. , Cohen Barbara G. F. , Stammerjohn Lambert W. , Happ Alan
Published: July 2017

A questionnaire survey dealing with working conditions, job stress factors, health complaints, and psychological mood state was filled out by approximately 250 video display terminal (VDT) operators and 150 nonoperator control subjects at five participating work sites. Clerical VDT operators reported higher levels of job stress and health complaints but little difference in psychological mood state than did professional VDT operators and the control subjects. The job stressors showing the greatest impact on the clerical operators dealt with workload, workpace, lack of control over job activities, boredom, and concerns about career development. The health complaints that showed the greatest differences between the groups dealt with visual, musculoskeletal, and emotional health problems. The results indicate that job content factors and VDT use interact to contribute to VDT operator problems.
Memory and Perception of Cartographic Information for Familiar and Unfamiliar Environments
Authors: Howard James H. , Kerst Stephen M.
Published: July 2017

Subjective estimates of the distance between sites on a familiar/unfamiliar map were obtained under various conditions (prior knowledge, after brief study, and while in view). Nonmetric multidimensional scaling was used to develop a cognitive map for each condition. Differences were noted in the relative compression of the two map axes and in the degree of site clustering that occurred. The systematic distortion observed when observers depended on their prior spatial knowledge was of particular interest. The scaled map for this group did not display the rectangular properties of the actual map, but was “squared up” in the observer's long-term store. In addition, all of the mental maps revealed a tendency for individual locations to cluster into three groups. This tendency was greater in the memory conditions than in the perceptual conditions.
Eye Movement Measurement of Readability of CRT Displays
Authors: Kolers Paul A. , Duchnicky Robert L. , Ferguson Dennis C.
Published: July 2017

Eye movement was recorded as people read texts presented on a CRT in two different spacings, two different character densities, and at five different scrolling rates. Differences in efficiency of reading single- and double-spacing were statistically significant, but were of little practical significance. Character densities of 35 characters or 70 characters per line favored the smaller-size character with respect to efficiency of reading. Comparison of scrolling rates suggested that the static page was processed more efficiently than was the page scrolled at the subject's preferred rate or at a rate 10% slower than that; pages presented faster than the preferred rate were read more efficiently. Little if any change in preferred rate occurred as a function of practice with 16 pages of text. Systems in which, by program control, text was presented at rates 10% or 20% faster than the preferred scrolling rate should lead to more efficient performance, but might create some problems of user acceptance.
Visual Fatigue and Cathode Ray Tube Display Terminals
Authors: Mourant Ronald R. , Lakshmanan Raman , Chantadisai Roongrojn
Published: July 2017

Study I investigated the effects of display type, amount of information presented, and display contrast on the visual mechanism during a visual search task. In the first phase, two subjects performed the visual task for four 3-h sessions. In the second phase, subjects were tested for two 6-h sessions. CRT usage for 3 h produced measurable visual fatigue in the eye movement and/or accommodation mechanism, as measured by increased durations to move from a near point and focus on a far point (and vice versa). Such visual fatigue was not present in the hard-copy visual search task.

In a second study, subjects performed the visual task for two 4-h sessions. Two h of CRT usage produced measurable fatigue in the eye accommodation mechanism as well as an increased blink rate. Such visual fatigue was also present in the hard-copy task but to a lesser extent.

In both studies, I-h breaks produced a marked reduction in visual fatigue indices.
Composing Letters with Computer-Based Text Editors
Authors: Gould John D.
Published: July 2017

This experiment studies how people compose letters using computer-based text editors and compares the results with longhand writing of similar letters. Ten research professionals who regularly use computer-based text editors composed four letters with each method. Results show that participants spent two-thirds of their time "planning" their text-edited letters, just as was found in previous experiments for writing, dictating, and speaking. Text-edited letters and written letters were of comparable quality, but text-edited letters required 50% more time to compose than did written letters. This was due in part to more changes, and to time taken in formatting, text positioning, and in reviewing and modifying the formatted version of text-edited letters.
A Comparison of Risk Selections
Authors: Fortenberry Jessie C. , Smith Leo A.
Published: July 2017

Comparisons were made of the risk that subjects selected, both for themselves and for someone else, in a task situation involving physical harm and risk that was based on performance skill at a motor task. Subjects performed in pairs, one being designated the decision maker and the other the performer. The decision makers selected tasks for the performers to attempt on the Purdue Pegboard. Hazard (objective probability of failure) was measured for eight conditions of potential gain (monetary payoff) and of loss (electrical shock). Results indicated that subjects selected essentially the same risk for someone else as they selected for themselves. Based on the study, it therefore appears reasonable to generalize the results obtained from single-person risk-taking studies to the decision maker in multiperson risktaking situations.
Developing Guidelines for Summarizing Information
Authors: Samet Michael G. , Geiselman Ralph E.
Published: July 2017

This study was conducted to test the validity and generalizability of previously developed guidelines for summarizing military message content. The task required staff officers to summarize a set of tactical messages; these summaries were then evaluated by knowledgeable raters. An analysis of the contents of the summaries reflected positively on the guidelines, and the raters judged the individual summaries prepared with the aid of the guidelines to be significantly "better" summaries than those prepared without guidelines. In addition, the 10 summaries that received the highest overall evaluations were used to derive a general suggested outline, or "schema," for describing the message content. This schema differed from another schema, derived from summaries of a different set of messages, only in terms of the inferences drawn from the intelligence data.
Does Welding Affect Visual Acuities or Color Sensitivity?
Authors: Caelli Terry , Finlay David
Published: July 2017

A group of 41 welders of varying ages and experience in the welding trade were examined for color discrimination, vernier, pattern, and stereoacuities. Results indicated usual binocular correlations and deterioration over age but no significant deviation from the population at large-even when individuals had experienced a series of "flashes" and other phenomena associated with welding. These results are to be contrasted with the equivalent auditory conditions, where hearing loss is known to occur.
A Selective Attention Test as a Predictor of Success in Flight Training
Authors: Gopher Daniel
Published: July 2017

Incorporation of a dichotic listening task of selective attention in the pilot selection test battery of the Israeli Air Force was studied using a group of 2000 flight cadets. In this test, subjects are presented with 48 auditory messages. Each message is composed of strings of words and digit names. Different strings are simultaneously presented to the two ears. Subjects are required to detect digit names in the relevant channel and to reconsider channel relevance upon indication. Three types of selective listening errors are recorded: omissions, intrusions, and switching errors. Flight cadets who had completed a two-year training program had significantly lower error scores on all attention measures. In addition, these measures had low correlations with all other tests of the pilot selection battery. Thus, attention capabilities appear to be an independent dimension that enhances the predictive validity of the present test battery.
The Correct Height of School Furniture
Authors: Mandal A. C.
Published: July 2017

Pupils were photographed by automatic camera during a four-hour examination. All of them were bent far over their tables in an unacceptable manner. An experiment was conducted to determine what height the pupils themselves preferred. Without exception, they preferred to sit much higher, which automatically placed them in a sitting position with a straight back. Revised design of furniture corrected the posture problem. It was concluded that the table should be at least half the person's height (80-90 cm for older pupils) and that the chair should be at least one-third the person's height (50-60 cm for older pupils). The seat should be capable of sloping forward 10-15 deg, and the forward sliding tendency counteracted by a small, fixed cushion. The tabletop should slope backward 10-15 deg.
Noise and Annoyance: A New Methodology
Authors: Corso Gregory M. , Moomaw Michael E.
Published: July 2017

Two experiments were conducted to investigate the effects of noise intensity on annoyance. The procedure involved the use of a visual signal to designate the impending occurrence of noise (a 1000-Hz pure tone). If the response was performed within 250 ms, noise was avoided; if the response was performed after 250 ms, the noise occurred but terminated with the response. In the first experiment, the findings indicated that the no-noise condition and 50-dBA values were significantly different from the 90-dBA value for both number of avoidance responses and response latencies. These results imply that avoidance responses and their associated latencies are indicators of annoyance. Experiment 2 investigated range effects on the number of avoidance responses and their latencies. An analysis of the 70-dBA condition for three groups resulted in significant differences between a group exposed to 50, 60, 70 dBA and one exposed to 70, 80, and 90 dBA. These results suggest that both the number of avoidance responses and the associated latencies are not only a function of the absolute intensity value, but are also a function of the range of intensities used. The advantages and disadvantages of the avoidance procedure are discussed.
Variation in Detectability of Multiple Flaws with Allowed Inspection Time
Authors: Geyer Lewis H. , Perry Ronald F.
Published: July 2017

The present study measured the effect of varying display duration upon the difference in discriminability, d', for separate versus mixed presentation of multiple flaws. Presentation interval was varied in three steps, from 1 to 4 s. Results demonstrate that the decline in d', in the mixed as compared with the separate presentation condition, represents an enforced speed-accuracy trade-off. Over the range of display intervals studied, the trade-off is notably linear. There were no significant differences in criterion location as a result of different experimental conditions.
The Sleep and Performance of Shift Workers
Authors: Tilley A. J. , Wilkinson R. T. , Warren P. S. G. , Watson B. , Drud M.
Published: July 2017

The sleep and performance of 12 male shift workers, operating a discontinuous, weekly alternating, three-shift system, were monitored over the course of one complete shift cycle. Compared with nocturnal sleep, day sleep was shorter in duration and was degraded in quality, and its sleep stages were temporally disrupted. Simple unprepared reaction time and four-choice reaction time were impaired at night, and simple reaction time deteriorated as a function of the number of days into the shift and the time on task. Sleep and performance changes can be primarily attributed to circadian factors; however, the deterioration in performance from night to night and with time on task is probably due to an accumulative sleep deficit. As far as sleep and performance are concerned, the best shift system is probably one having a short rotation cycle, with afternoon shifts or rest days preceding and following the night shift.
Using Visual Lobe Area Measurements to Predict Visual Search Performance
Authors: Kraiss Karl-Friedrich , Knäueuper Annette
Published: July 2017

After a review of the pertinent literature, a procedure to predict search performance is presented, which is based on visual lobe area measurements. The procedure also distinguishes between random and systematic searching strategies. A task network model has been worked out that permits one to dynamically simulate visual search with various field sizes, visual lobe areas, and eye-movement characteristics. The validity of the proposed predicting method is demonstrated by comparison with experimental data as well as by simulation runs using the prediction model.
The Relative Suitability of Four Dot--Matrix Sizes for Text Presentation on Color Television Screens
Authors: Pastoor Siegmund , Schwarz Elmar , Beldie Ion P.
Published: July 2017

Characters with four dot--matrix sizes (5 x 7, 7 x 9, 9 x 13, and 11 x 15) were tested as to their suitability for the presentation of characters on standard home color television sets. Subjects performed five different tasks and rated the various character sizes. Their qualitative performance for all tasks was the same with each of the different character sizes; the amount of time necessary to complete the tasks, however, varied up to more than 20%. In all tasks, the worst performance was obtained with the smallest character size. Since the 9- x -13 character size was rated significantly better than the smaller character sizes, we recommend that this size be used for text display on color television screens.
RESEARCH NOTE Fixed versus Variable Letter Width for Televised Text
Authors: Beldie Ion P. , Pastoor Siegmund , Schwarz Elmar
Published: July 2017

The efficiency of two character sets to be used on television screens was evaluated. Subjects performed various tasks (reading, error identification, line finding) with each of the two character sets. The text was presented using dot--matrix characters having either a fixed matrix size or a variable width. The variable--matrix character design resulted in significantly improved efficiency in two of the three tasks, and this character design is recommended for use on television screens.
RESEARCH NOTE A Comparison of Paging and Scrolling for Changing Screen Contents by Inexperienced Users
Authors: Schwarz Elmar , Beldie Ion P. , Pastoor Siegmund
Published: July 2017

Paging and scrolling were compared as to their relative suitability for determining which part of a body of information is to be displayed on a screen. Unpracticed subjects performed three different tasks (word reading, line searching, sorting) with both modes of operation. The subjects also rated the suitability of the two modes of operation for each task. Paging was preferred by inexperienced users and it resulted in better performance on the sorting task.
Criterion Control in Signal Detection
Authors: Vickers D. , Leary J. N.
Published: July 2017

Observers were required to detect a signal that underwent a decrease in probability of occurrence throughout a session. Contrary to what might be expected with the "ideal observer" hypothesis of signal detection theory, changes in the proportions of hits and false alarms, as well as in their associated response times and confidence ratings, indicated that observers reacted to the decrease in signal probability by adopting a less stringent criterion for making signal responses. The empirical pattern of changes in response proportions is compared with that predicted by a response stabilization process. An adaptation----level hypothesis is then proposed, in which the cutoff adopted by the observer is equal to the cumulatively based mean of all the sensory intensities experienced by the observer up to that trial. Such a mechanism for criterion control offers a simple but very general explanation for criterion changes in signal detection.
RESEARCH NOTE Scaling of Flash Rate for a Deceleration Signal
Authors: Mortimer Rudolf G. , Kupec James D.
Published: July 2017

This study is concerned with determining the number of different flash rates that could be used in an automobile braking signal to inform a following driver of the degree of deceleration. Two methods, magnitude estimation and just noticeable differences (iND) scaling, were employed to relate perceived flash rate to the physical frequency at which an automobile stop signal lamp was flashing. Differences between red and yellow lamps were examined, but no effects were found due to the lamp color. A category scaling procedure showed that only three flash rates between 1 and 7 Hz could be discriminated by absolute judgments. The iND and magnitude estimation experiments yielded similar flash rates (e.g., 1.0, 2.6, and 6.8 Hz) for the presentation of the deceleration information.
The Effects of Cuing in Time-Shared Tasks
Authors: Chechile Richard A. , Sadoski Darleen M.
Published: July 2017

Two divided-attention experiments were performed to evaluate the effectiveness of verbal and symbolic cuing on the primary task of editing flight route-way-point information. Cuing conditions were contrasted with a no-cue control. Symbolic cuing consisted of directing the operators to the appropriate keys throughout the sequence of primary task steps. Verbal cuing consisted of a short instruction displayed on the CRT just prior to the next step. In Experiment 1, symbolic cuing proved effective in improving editing accuracy. In Experiment 2, symbolic cuing resulted in reduced early-trial edit-completion time. Verbal cuing, however, was not effective on these tasks in either experiment. It is theorized that symbolic cuing lightened the cognitive load, whereas verbal cuing did not reduce the cognitive load since it still required attention to read the verbal message.
Characteristics of Reading Rate and Manual Scanning Patterns of Blind Optacon Readers
Authors: Hislop David W. , Zuber B. L. , Trimble John L.
Published: July 2017

Tactual reading is slow compared with sighted reading, and the rate-limiting constraints imposed on tactile readers are only vaguely understood. Like the eye movements of sighted reading, the text-scanning hand movements of tactual reading provide a means to investigate the operative system. We examined the reading hand movements of 10 blind readers using the Optacon, the electronic reading aid used most commonly by blind readers. Subjects read texts of graded difficulty, and their reading hand movements were recorded.

Rate and scanning measures were used to characterize reading performance. The group mean reading rate was found to be 28.2 words/min. Reading rate measured in letter spaces per minute was independent of text difficulty.
Human and Machine Performance in an Inspection Task
Authors: Drury Colin G. , Sinclair Murray A.
Published: July 2017

Inspectors inspected a batch of 162 metal cylindrical items. These were later inspected by a prototype inspection device so that performance of human and machine could be compared. Receiver operating characteristic (ROC) curves were plotted for each of four types of fault for the inspection device. The performance of each inspector was compared with these ROC curves to assess overall performance. Inspectors performed significantly better than did the prototype machine, largely because of the more sophisticated decision-making capabilities of humans. The inspection device could locate most faults but was unable to classify them as acceptable or rejectable with the same consistency as inspectors.
A Comparison of Relaxation Methods for Reducing Stress in Nursing Personnel
Authors: Murphy Lawrence R.
Published: July 2017

The efficacy of a work-based stress reduction training program for nursing personnel was assessed. Nurses received training in EMG biofeedback, progressive muscle relaxation, or self-relaxation, via daily 1-h sessions conducted during their customary working hours for two consecutive work weeks. Progressive muscle relaxation training produced significant within-session decreases in muscle activity levels, whereas biofeedback training produced significant increases in hand temperature, signifying lower autonomic arousal. All three groups reported improvements on measures of trait anxiety after training. At a three-month follow-up, the biofeedback group reported increases in the amount of work energy and perceived effectiveness of the coping skills when used at work. The muscle-relaxation group reported increases in the ability to cope with stress, and both trained groups reported coping with stress more frequently than did the control group. The control group reported a significant increase in job dissatisfaction compared to the trained groups. The results offer some support that biofeedback and muscle relaxation may be useful methods for reducing arousal levels and improving coping skills of workers.
The Psychophysical Approach in Manual Lifting---A Verification Study
Authors: Mital Anil
Published: July 2017

An experiment was conducted to verify the psychophysical methodology used for determining lifting capabilities of workers. After estimating during a 25-min period what they could lift for 8 h, males lifted for 8 h. The amount lifted was only 65% of the estimated value. Females, on the other hand, lifted 84% of the estimated weight. When the lifting duration increased from 8 h to 12 h, males lifted only 70% and females lifted 77% of the estimated weights. The metabolic energy expenditure rate of the subjects also decreased significantly with time as the loads were reduced. Heart rates remained relatively constant at about 100 beats/min, even though energy expenditure rates decreased over the 12-h period. This could indicate that the subjects were sensitive to their general state of physiological strain in such work and adjusted the loads and corresponding energy expenditure rates to maintain a relatively constant circulatory burden.
An Ergonomics Approach for the Design of Manual Materials-Handling Tasks
Authors: Ayoub M. M. , Selan Joseph L. , Liles Donald H.
Published: July 2017

The frequency, severity, and cost of manual materials-handling (MMH) injuries dictate that the design of these tasks and the assignment of employees to them ensure that the demands of the job do not exceed the capacity of the worker. This paper proposes the use of the job Severity Index (JSI) as a tool for job design and employee placement. The JSI is defined as the time- and frequency-weighted average of the maximum weight required by each task divided by the selected lifting capacity given the lifting task conditions. This paper illustrates the relationship between the JSI and the frequency, severity, and cost of MMH injuries. Procedures for job design and employee placement based on the JSI are discussed and examples of the use of the JSI in industry are given.
Hand Placement in Manual Materials Handling
Authors: Drury Colin G. , Pizatella T.
Published: July 2017

This paper reviews the use of handles on containers and manually propelled vehicles. It is concluded that handle shape and size are relatively easy to define, but placement of handles on containers represents a more difficult problem. Laboratory and field studies of hand and handle placement are reviewed with the conclusion that handles should be placed so as to give both horizontal and vertical stability, except for heavy lifting, in which a symmetrical handle placement may be preferred, as it minimizes arm forces.
Redundant Color Coding on Airborne CRT Displays
Authors: Luder Catriona B. , Barber Paul J.
Published: July 2017

An experiment is described that compares the use of redundant color coding for search and identification tasks under dual-task conditions; subjects made judgments about the state of components of a systems-management display while performing a compensatory tracking task.

The availability of redundant color coding on the secondary task resulted in a global improvement in tracking performance (primary task) that applied at all times, even when subjects were not attending to the systems-managment display. With regard to the response-time data for the color-coded display, redundant color coding improved search performance, but there was no benefit for performance on the identification task. The implications of the results for hypotheses relating to the serial or parallel processing of shape and color, and for cockpit applications generally, are discussed.
From Control Systems to Knowledge Systems
Authors: van Cott Harold P.
Published: July 2017

Historically, the human species has been dependent upon technology for survival. This dependency placed people in a control loop from which they learned that mechanical cause and-effect models were useful as explanatory mechanisms. These models were selectively reinforced to the exclusion of other forms of explanation. As the human's role shifts from that of a controller to a supervisor, new forms of rationality are reinforced. This process is being facilitated by new information technologies that demassify images and allow the individual to construct a highly personal understanding of human beings and nature.
The Development of a Time-Related Measure to Describe Driving Strategy
Authors: Godthelp Hans , Milgram Paul , Blaauw Gerard J.
Published: July 2017

A preview prediction model is used to describe the potential role of a fixed control strategy in automobile driving. On the basis of this model the time-to-line-crossing (TLC) concept was developed, representing the time necessary for the vehicle to reach either edge of the driving lane. An experiment on straight road driving was conducted to analyze whether TLC would be helpful to understand a driver's strategy in an occlusion task. The results indicate a close correspondence between TLC and driver's self-chosen occlusion times. In addition to conventional measures such as lateral position data, TLC seems a valuable description of driving performance.
Glare From Automobile Rear-Vision Mirrors
Authors: Olson Paul L. , Sivak Michael
Published: July 2017

Four studies were carried out to measure disability and discomfort glare from automotive rear-view mirrors. The results of the first three studies, which were concerned with disability effects, indicated that there are significant losses in forward visibility even at glare levels associated with low-beam headlamps. The last study measured comfort levels and showed that drivers rated even moderate glare levels uncomfortable, especially if they were exposed to them for a relatively long period of time. The implications of these findings for headlamp design are discussed.
An Information Transmission Analysis of Signal Flash Rate Discriminability
Authors: Tolin Philip
Published: July 2017

Contingent uncertainties were used to determine the ability of subjects to discriminate changes in the flash rate of a signal light. The limit of information transmission was achieved with a rate difference of approximately 4%. However, care should be taken to ensure a minimum rate difference of 25%.
Synthesized Speech Rate and Pitch Effects on Intelligibility of Warning Messages for Pilots
Authors: Simpson Carol A. , Marchionda-Frost Kristine
Published: July 2017

In civilian and military operations, a future threat warning system with a voice display could warn pilots of other traffic, obstacles in the flight path, and/or terrain during low altitude helicopter flights. The present study was conducted to learn whether speech rate and voice pitch of “phoneme” synthesized speech affects pilots' accuracy and response time to typical threat warning messages. Helicopter pilots engaged in an attention-demanding “flying” task and listened for voice threat warnings presented in a background of simulated helicopter cockpit noise. Performance was measured by flying task performance, threat warning intelligibility, and response time to threat warnings. Pilot ratings were elicited for the different voice pitches and speech rates. Significant effects were obtained only for response time to messages and for pilot ratings, both as a function of speech rate. For the few cases when pilots forgot to respond to a voice message, they remembered 90% of the messages accurately when queried for their response 8 to 10 s later.
On the Psychophysics of Workload: Why Bother with Subjective Measures?
Authors: Gopher Daniel , Braune Rolf
Published: July 2017

Psychophysical functions describe the relationship between variations in the amplitude of a defined physical quantity and the psychological perception of these changes. Examples are brightness, loudness, and pain. The regularities of these relationships have been formulated into psychophysical laws. The measurement methodology of psychophysical scaling has been refined by the Harvard group led by S. S. Stevens, who proposed a power function as a general form for such laws. The main argument of the present article is that a similar scaling approach can be adapted to the measurement of workload and task demands based upon subjective estimates. The rationale is that these estimates, like other psychophysical judgments, reflect the individual's perception of the amount of processing resources that the subject invests to meet the demand imposed by a task. This approach was successfully applied to the assessment of 21 experimental conditions given to a group of 60 subjects. The paper discusses the main results of this effort and their implications to theory and application in human performance.
Automation in Training and Education
Authors: Kearsley Greg , Seidel Robert J.
Published: July 2017

Computer-based training and education are becoming increasingly prevalent and important. This article discusses the history of automated instruction, current applications, issues and problems, and future prospects. Current applications include such traditional uses of computers as testing, drills, tutorials, games, simulations, and student management. New applications include embedded training, computer literacy, interactive videodisc, and electronic lectures. The most important issue in automated instruction at present is the time and costs associated with the development of courseware. Other important problems include the difficulty of implementing individualized instruction in organizations accustomed to classroom teaching, the scarcity of educators who are computer literate, and the evaluation of courseware. Microcomputers have greatly accelerated the growth of computer-based instruction in all domains. Intelligent CAI, authoring systems, hand-held computers, speech processing, and telecommunication technologies such as videotex are seen as shaping the future direction of automated instruction.
Computer Abbreviations: Evidence and Synthesis
Authors: Ehrenreich S. L.
Published: July 2017

This paper examines the experimental data on 11 abbreviation techniques for use with computer systems. The techniques include abbreviations based on intuition, abbreviations derived from formal rules, and military abbreviations. Although the comparison of user performance on the abbreviations produced by these different techniques is complicated by the varying conditions under which they were tested, trends in the data are apparent. This paper presents design recommendations based on this evidence as well as conjecture on how to further improve operator performance.
Effects of Rest and Secondary Task on Simulated Truck-Driving Task Performance
Authors: Drory Amos
Published: July 2017

The study was designed to examine the effects of extra task stimulation and extra rest on performance and fatigue of haul truck drivers engaged in a simulated driving task. Sixty male subjects, randomly selected from the population of truck drivers in a large mining company, operated a driving simulator for a period of 7 h. A 2 x 3 experimental design was employed including two levels of rest conditions and three levels of secondary-task manipulations. The results show that performance and perceived fatigue were significantly higher when a secondary task involving voice communication was added to the basic driving task, but an added vigilance task had less effect. An extra 30-minute rest period in the middle of the experimental session significantly alleviated the reported experience of fatigue but did not affect performance. The results are discussed in terms of their relevance to actual industrial driving tasks.
Repeated Measurements of Spatial Ability with the Manikin Test
Authors: Carter Robert , Woldstad Jeffrey
Published: July 2017

A task reflecting spatial ability, the Manikin Test, was examined for parallelism of repeated measurements. (Only parallel test scores are suitable for repeated measurement of human performance.) The results bear on some theories of individual differences. Egan's theory that latency scores reflect spatial ability (whereas accuracy scores reflect something else) was supported, as was Jones's theory that individual differences stabilize with practice. The hypothesis of Baron and Treiman, that skill transfers between tests of the same ability, was not supported. The results illustrate the principle that not all tasks and scores are useful for repeated measures. The Manikin Test log latency score was shown to be suitable for repeated-measures applications.
Tunnel Vision Induced by a Foveal Load Manipulation
Authors: Williams Leonard J.
Published: July 2017

In a tachistoscopic dual-task study, the foveal load of a primary task was varied, and subjects were required to report the orientation of a simultaneously presented peripheral line that could occur at anyone of six retinal locations (3, 6, or 9 deg from central fixation in either the left or right visual field). Overall peripheral (secondary) task accuracy was significantly superior for subjects given a low foveal load that required naming a letter drawn from a set of two alternatives as compared with the accuracy of subjects who had to choose a foveal response from among six alternatives. Foveal load interacted strongly with retinal eccentricity. Accuracy of peripheral line-orientation discrimination deteriorated much more rapidly with increases in retinal eccentricity for the high-foveal-load group than for the lowfoveal-load group. These results are discussed in terms of a tunnel-vision model.
Internalizing the System Dynamics for a Second-Order System
Authors: Eberts Ray , Schneider Walter
Published: July 2017

Three groups of subjects, differing in the kinds of augmentation provided, were trained to control a continuously moving track in a second-order system. Differences in performance among the three groups occurred only in transfer experiments when subjects were required to apply their knowledge, or their internal model, to solve system problems. These results indicated that subjects in a parabola-augmented group had learned to internalize this cue and mentally manipulate it to solve system problems even when the cue was not displayed. Subjects in the other two groups, a point-augmented group and a nonaugmented control group, used a set of simplifying rules, some correct and others incorrect, to guide their behavior. The results indicated that accurate control of the system does not necessarily imply that the operator's internal model of the system is also accurate. In addition, augmentation that made the system appear consistent was important in the development of an internal model.