bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Locus of Control and Task Complexity on Prospective Remembering
Authors: Wichman Harvey , Oyasato Aimee
Published: July 2017

High school students were divided into two groups (internals and externals) by a median split of scores on the personality dimension, locus of control. While performing an intensive intervening activity, participants were required to remember to perform a planned action at specified times. In addition, two situational variables were manipulated. One variable was difficulty of intervening task---either simple or complex. The other variable was type of memory activity---either habitual (structured) or episodic (unstructured). ANOVA main effects showed better performance for simple tasks and habitual memory structure. However, all two-way interactions were significant, thus qualifying the main effects as a consequence of the interaction of the two situational variables with the personality variable and with each other
A Comparison of Rating Scale, Secondary-Task, Physiological, and Primary-Task Workload Estimation Techniques in a Simulated Flight Task Emphasizing Communications Load
Authors: Casali John G. , Wierwille Walter W.
Published: July 2017

Sixteen potential metrics of pilot mental workload were investigated regarding their sensitivity to communication load and their intrusion on primary-task performance. A moving-base flight simulator was used to present three cross-country flights. The flights varied only in the difficulty of the communications requirements. Rating scale measures were obtained immediately postflight; all others were taken over a 7-min segment of the flight task. The results indicated that both the Modified Cooper-Harper Scale and the workload Multi-descriptor Scale were sensitive to changes in communications load. The secondary-task measure of time estimation and the physiological measure of pupil diameter were also sensitive. As expected, those primary-task measures that were direct measures of communicative performance were also sensitive to load, whereas aircraft control primary-task measures were not, attesting to the task specificity of such measures. Finally, the intrusion analysis revealed no differential interference between workload measures.
Readability of Text Scrolled on Visual Display Terminals as a Function of Window Size
Authors: Duchnicky Robert L. , Kolers Paul A.
Published: July 2017

Readability of text scrolled on visual display terminals was studied as a function of three different line lengths, two different character densities, and five different window heights (either 1, 2, 3, 4, or 20 lines). All three variables significantly affected reading rate, but to markedly different extents. Lines of full and two-thirds screen width were read, on average, 25% faster than lines of one-third screen width. Text appearing at a density of 80 characters per line was read 30% faster than text in a format of 40 characters per line. Text appearing in windows four lines high was read as efficiently as text in 20-line window, and text in one- or two-line windows was read only 9% more slowly than text in 20-line window. Comprehension of the passages did not vary as a function of window size, indicating that subjects maintained a constant level of comprehension by varying their reading rate. Implications of the results for mixing text and graphics and for limited-capacity electronic displays are discussed.
A Study of Methods for Engaging Moving Targets
Authors: Schendel Joel D. , Johnston Shirley D.
Published: July 2017

This research focused on two methods for engaging moving targets: tracking and trapping. Interest was in determining the conditions under which either method would prove superior. It was hypothesized that a shooter's ability as well as the speed and range of the target might affect the outcome. All testing was accomplished on an M16Al rifle marksmanship simulator that permitted the manipulation of the target's speed (velocity or duration) and range (apparent size). Based on a pretest, subjects were evenly divided into high- and lowability groups. All subjects then fired two 24-target sequences, being instructed to track and then trap targets or vice versa. Following testing, subjects were required to indicate their preference for either tracking or trapping. Trapping proved superior for low-ability subjects and for the farthest (smallest) target moving at the slowest observed speed. Tracking proved superior for high-ability subjects and for the closest (largest) target moving at the fastest observed speed. Subjects generally preferred to use the method that produced better results.
Incised Grids: Enhancing the Readability of Tangible Graphs for the Blind
Authors: Barth John L.
Published: July 2017

The transformation of a graphic display into tangible form for blind persons is usually achieved by raising the entire image above the surface. In the case of tangible line graphs, this format causes readability problems by degrading figure-ground (data-curve/grid) differentiation. This study assessed the feasibility of a new design format involving both raised and incised elements in the same display. The results from 24 blind students in grades 4 through 7 indicated that an incised-grid/raised-data-curve format significantly improves graph-reading performance relative to a raised-grid/raised-data-curve format. The importance of designing displays in ways that are compatible with the perceptual-motor capabilities of blind persons is discussed.
Deciding the Existence of a Time-Sharing Ability: A Combined Methodological and Theoretical Approach
Authors: Ackerman Phillip L. , Schneider Walter , Wickens Christopher D.
Published: July 2017

Experimental and statistical methods for examining individual differences in dual-task performance and time-sharing ability are reviewed and criticized. Previous data and analysis procedures are generally inadequate to evaluate a time-sharing ability. Errors resulting from unsophisticated use of correlational and factor analytic procedures are described. Four previous studies that concern time-sharing are considered in detail. The nature of task selection, scoring methods, and control of practice and reliability issues are discussed. Based on a reanalysis of available data, a time-sharing ability is not rejected. Simulation, incorporation of theory in planning models, and crucial tests of the hypotheses are proposed as methods for assessing the time-sharing ability.
A Search Task to Assess Visual Lobe Size
Authors: Courtney Alan J.
Published: July 2017

Using a sample of 18 Cantonese Chinese subjects that covered a wide range of acuity scores and age, very high correlations were obtained between time taken on a simple card-sorting task and visual lobe dimensions. With subjects younger than 30 years of age and having good acuity, similar but not so highly significant correlations were found. Only one card-sorting session was required to produce useful data for between-subjects comparisons so that the card-sorting task may provide a simple, fast, and valid measure of a visual function of great importance to search performance. Also, a simple means of calculating visual lobe size from tachistoscopically presented stimulus material was tested and found to produce comparable results to those obtained using a more complex method of calculation involving data transformation.
Doing the Same Work with Hard Copy and with Cathode-Ray Tube (CRT) Computer Terminals
Authors: Gould John D. , Grischkowsky Nancy
Published: July 2017

Much public concern has centered on possible fatiguing effects of using CRT terminals in one's work. Previous experiments have not carefully distinguished the effects of using a CRT display per se from the effects of the work itself This experiment studies this problem by having people do the same task with a CRT display and with hard copy. Twenty-four participants proofread from a CRT on one day and from hard copy on another day. No change throughout the day in participants' proofreading performance (speed and accuracy), feelings (about the comfort of their eyes, body, mind, and work), or vision (acuity, contrast, and flicker sensitivity, phoria) could be attributed to using CRT terminals. Participants did proofread from hard copy about 20 to 30% faster than from a CRT, however.
Reading of Continuous Text on Video Screens
Authors: Kruk Richard S. , Muter Paul
Published: July 2017

In three experiments, the finding of slower reading of text from a video screen than from a book was replicated, and several possible reasons for this effect were explored. Extra time (9 s) taken to fill the screen had no significant effect on reading time in the video condition. Similarly, varying the contrast ratio of the video image and the distance between the screen and the reader had no effect on reading speed. The format used in the video condition (39 characters per line and 20 lines per page) produced slower reading than did a format typical for books (60 characters per line and 40 lines per page), but this effect alone (9.5%) could not account for the difference in reading speed between the book and video conditions (24.1%). The reduced reading speed was partly overcome by avoiding single spacing, which produced 10.9% slower reading than did double spacing in the video condition.
Effects of Video Display Terminals in a Business Office
Authors: Starr Steven J.
Published: July 2017

A self-administered questionnaire was completed by 211 workers in a business office who used video display terminals (VDTs) to do their work and by 148 control subjects who did the same job using paper documents instead of VDTs. The groups exhibited few differences in the likelihood and intensity of on-the-job physical discomfort, and no differences in the perception of discomfort that lingered after work. Almost identical proportions of subjects in the two groups reported that their vision had grown worse recently. Differences were found in job satisfaction and concerns about job security, but most of these favored VDT users. The use of an intermediate standard of comparison showed that the visual quality of VDT displays was preferred to that of the paper documents they replaced. The results confirm and extend the findings of the author's earlier study of telephone operators and show that VDTs need not be unusually potent sources of discomfort and disaffection among office workers.
Short-Term Changes in Eyestrain of VDU Users as a Function of Age
Authors: Hedman Leif R. , Briem Valdimar
Published: July 2017

Operators at a Swedish Telecom Directory Enquiry Centre participated in tests of eyestrain including measures of accommodation and convergence near points, focusing accuracy, and dark focus. The optometric measurements were conducted before and after work at a visual display unit (VDU) and in two control conditions, with or without job rotation. Visual focus of accommodation was measured with a modified version of the field laser optometer method. The results showed no differential eyestrain effects, either in near points of accommodation and convergence or in focusing accuracy, between the three tasks. A small, age-dependent difference in dark focus was apparent after work in the job-rotation phase. It is concluded that the VDU work was not in itself conducive to eyestrain, and that, under the job conditions obtained in the present investigation, changes in the variables studied must be primarily attributed to other factors, such as age and workload on the day of testing.
Blocking Learner Error States in a Training-Wheels System
Authors: Carroll John M. , Carrithers Caroline
Published: July 2017

Some of the most troubling problems for users of computer equipment arise in the getting started stage. A “training-wheels” system was designed for a commercial word processor in which system functions that new users typically do not need, but which can be springboards for errors and confusions, were disabled. The training-wheels word processor improved learning efficiency in two experiments, one of which examined learning by doing and the other, learning by the book.
Text-Editing Performance with Partial-Line, Partial-Page, and Full-Page Displays
Authors: Neal Alan S. , Darnell Michael J.
Published: July 2017

Two experiments were conducted to examine how the amount and format of text shown on text editor displays affect text-editing performance. In the first experiment, 28 typists used both a partial-line display and a partial-page display. In the second experiment, 20 typists used both a partial-page and a full-page display. The displays in both experiments were connected to the same text-editing system. In each experiment, typists completed 384 editing tasks using each display. Each editing task required typists to make a revision, which was marked on a printed copy of a document. The results showed that text-editing performance was largely unaffected by the amount of text displayed; where differences occurred, they generally favored the displays showing more text.
The Effects of Modes on Text Editing by Experienced Editor Users
Authors: Poller Merle F. , Garter Susan K.
Published: July 2017

Experienced nonclerical users of two screen editors, vi and emacs, were asked to do a series of editing and composition tasks. The results suggest that moded editing, as exemplified by the vi editor, may be preferable far fixed editing tasks, whereas modeless editing, as exemplified by the emacs editor, may have some advantages during composing. The vi subjects left fewer errors in their final files and showed a tendency to do the editing tasks faster, though the time differences may have resulted from differences in typing rates. They made few mode errors, and those few were rapidly and easily corrected. The emacs subjects tended to do more of their editing during the first-draft stage of composing than did the vi subjects; this result agrees with the hypothesis that modeless editing is more flexible than moded editing. However, the total editing done while composing, the composing time, and most writing-style variables were similar far the two groups.
A Method for Pragmatic Communication in Graphic Displays
Authors: Simcox William A.
Published: July 2017

This paper presents a method for connotatively weighting information presented in graphic displays. The method involves determining a compatibility (unction that describes the degree of correspondence between an implied attribute of the display and the linguistic category that summarizes values of this attribute. Compatibility functions can then be used to guide the graph-construction process.
A Brief History of Aviation Psychology
Authors: Koonce Jefferson M.
Published: July 2017

This paper presents an overview of the field of aviation psychology from its pre- World War I beginnings to current problems and opportunities for today's aviation psychologists. This brief survey covers some of the more significant early activities of aviation psychologists in the United States and Europe.
Pilot Errors as a Source of Workload
Authors: Hart Sandra G. , Bortolussi Michael R.
Published: July 2017

A pilot opinion survey was conducted to develop a database for creating simulation scenarios that impose predetermined levels of pilot workload. Twelve pilots estimated the effect of 163 events and activities (which they had encountered during their previous flying experiences) on performance, effort, workload, and stress. The events, described in the context of flight scenario segments, included control, navigation and communications activities, aircraft and system failures, and pilot errors. In general, workload, stress, and effort ratings were significantly correlated with each other but not with performance ratings; however, some different response patterns were found as a function of flight segment (e.g., workload, stress, and performance, but not effort, ratings varied with flight phase) and type of event. Errors were rated as a significant source of change for workload, stress, and performance, suggesting that errors could be conceptualized as a cause of workload rather than as a symptom.
An Investigation of the Effectiveness of Pilot Judgment Training
Authors: Buch Georgette , Diehl Alan
Published: July 2017

Pilot decisional errors have always been a significant factor in aviation accidents. Pilot judgment, however, traditionally has been viewed as an intrinsic quality or a by-product of flying experience. Only recently has it been examined as a potential flight-training requirement. Over the past 10 years, initial steps have been taken in Canada and in the United States to validate the effectiveness of pilot judgment training. In this study, the judgment skills of Canadian civilian air cadets who received judgment training both in the classroom and in flight while earning a private pilot license were compared with the skills of a control group of cadets who received conventional training. The judgment skills of all subjects were measured during short, well-structured cross-country “observation flights.” The results indicate that those subjects who had received judgment training averaged fewer decisional errors than did their counterparts who had received the standard training only. These results suggest that pilot judgment can be improved with training
Computer-Aided Testing of Pilot Response to Critical In-Flight Events
Authors: Giffin Walter C. , Rockwell Thomas H.
Published: July 2017

This research on pilot response to critical in-flight events employs a unique methodology including an interactive computer-aided scenario-testing system. Navigation displays, instrument-panel displays, and assorted textual material are presented on a touch-sensitive CRT screen. Problem diagnosis scenarios, destination-diversion scenarios and combined destination/diagnostic tests are available. A complete time history of all data inquiries and responses is maintained. Sample results of diagnosis scenarios obtained from testing 38 licensed pilots are presented and discussed.
Emerging Office Automation Systems
Authors: Helander Martin G.
Published: July 2017

The acceptance of novel office automation devices and systems depends primarily on their potential for increasing productivity and their ease of use. This paper discusses the technology and ergonomics of several new office automation devices. Four major office interactions are noted: transacting, documenting, elephoning, and meeting. For each, human factors characteristics are examined to provide an understanding of which systems can most easily be incorporated into existing office environments. Systems design methodologies, originally developed for military use, will find increasing utility for solving complex civilian problems. There is now a need to apply this methodology to the design of equipment, tasks, and systems. More research is needed to increase our understanding of office automation and how it may be implemented. Particularly important are comparative field studies of office tasks and office automation devices and systems.
Designing the User-Friendly Robot: A Case History
Authors: Shulman Harvey G. , Olex Michael B.
Published: July 2017

The process of designing the user interfaces for an industrial spray-painting robot manufactured by the Nordson Corporation is described in the form of a case history. Human factors engineering was applied to the design of the system control panel, to a control grip on a special version of the robot's arm used in programming the system, and to the specialized microcomputer operating system used to manage the task of programming, monitoring, and operating the system.
Automation and the Individual: Comprehensive and Comparative Views
Authors: Parsons H. McIlvaine
Published: July 2017

Automation as a process of supplanting humans or combinations of humans and devices with devices or other human-device combinations has many aspects and effects on individuals. To provide a comprehensive view of this complex domain, these aspects and effects are set forth in two frameworks. To suggest generalizations, comparisons are offered between factory and office automation, with examples of similarities and differences.
Minimizing User Search Time in Menu Retrieval Systems
Authors: Lee Eric , Macgregor James
Published: July 2017

The optimal structuring of menu indexes in computerized information retrieval is examined. The number of alternatives per page that minimizes search time is determined as a function of the human and machine factors of search strategy, scanning time, key-press time, and computer response time. For a wide range of conditions, the optimal number of alternatives per page is in the range of from four to eight, with limiting integer values of three and four for exhaustive and self-terminating search, respectively.
Studies on Ergonomically Designed Alphanumeric Keyboards
Authors: Nakaseko M. , Grandjean E. , Hüunting W. , Gierer R.
Published: July 2017

A keyboard concept based on biomechanical considerations was studied with 51 trained typists. The keyboard is split into two half-keyboards. An adjustable model allowed study of the preferred settings of opening angles, lateral inclinations, and distances of the split keyboard. The preferred split keyboards decrease the lateral deviation of the hands, and the use of a large forearm-wrist support is associated with a backwards leaning of the subjects and with an increased pressure of forearm-wrists onto the support. After the typing tasks, about two-thirds of the subjects asserted that they preferred the split keyboard models. Less pain and an increased feeling of relaxation were reported by the subjects when operating the split keyboards.
Is the Airport Symbol Sufficient to Convey Route Information?
Authors: Whitaker Leslie A.
Published: July 2017

The silhouette of a jet aircraft that is used as an airport symbol on highway route markers was evaluated to determine the strength of its directional information when used with an arrow route marker and when used alone. Signs with the plane silhouette plus the route arrow were combined as described in the Manual of Uniform Traffic Control Devices; that is, no agreement between plane orientation and route direction was required. This produced signs with concordance, discordance, and orthogonal relationships between the plane orientation and the route direction. In addition, signs with the plane silhouette only (without a route arrow) were tested. Without prior instruction, the majority of the observers did not interpret the airport symbol as providing directional information without a route arrow. However, after instructions, the mean response time for signs of plane silhouettes alone (752 ms) was comparable to response times (765 ms) for signs with concordance between plane-silhouette orientation and route-arrow direction. Response times to signs with orthogonal and discordant relations between plane and arrow direction were significantly slower (834 ms and 865 ms, respectively).
Documentation of Concurrent Programs
Authors: Boehm-Davis Deborah A. , Fregly Andrew M.
Published: July 2017

This research explores the usefulness of control-flow versus interprocess communications information in documentation of concurrent processing programs. Programmer performance was examined on a modification task where modifications were made to either the data structure or the control flow of a program. The results suggest that for simple programs and simple modifications, it is not crucial whether interprocess communications or control-flow information is highlighted in the documentation format. For more complex problems, it would appear that detailed control-flow information is not necessary, and, in fact, may interfere with making the modification.
A Study of the Reduction of Fatigue Impact on Productivity through Optimal Rest Break Scheduling
Authors: Janaro Ralph E. , Bechtold Stephen E.
Published: July 2017

The variable-k with penalty (VKP) model was developed to determine optimal individual rest break policies. The goal is to maximize worker output over a specified time horizon. A rest break policy consists of the number, duration, and placement of rest breaks. This study examined the validity of the VKP model in an experiment that involved 10 subjects engaged in the demanding physical task of riding an ergometer. In separate sessions, the subjects first used a self-determined rest break policy and then the model's policy. A comparison of the results indicated that, on the average, work output increased by nearly 13% when the subjects used the model's policy.
Evaluation of 16 Measures of Mental Workload using a Simulated Flight Task Emphasizing Mediational Activity
Authors: Wierwille Walter W. , Rahimi Mansour , Casali John G.
Published: July 2017

As aircraft and other systems become more automated, a shift is occurring in human operator participation in these systems. This shift is away from manual control and toward activities that tap the higher mental functioning of human operators. Therefore, an experiment was performed in a moving-base flight simulator to assess mediational (cognitive) workload measurement. Specifically, 16 workload estimation techniques were evaluated as to their sensitivity and intrusion in a flight task emphasizing mediational behavior. Task loading, using navigation problems presented on a display, was treated as an independent variable, and workload-measure values were treated as dependent variables. Results indicate that two mediational task measures, two rating scale measures, time estimation, and two eye behavior measures were reliably sensitive to mediational loading. The time estimation measure did, however, intrude on mediational task performance. Several of the remaining measures were completely insensitive to mediational load.
The Prediction of Target Detection Underwater: Some Limitations of a Visibility Model
Authors: Emmerson Paul G.
Published: July 2017

For some viewing conditions, it is possible to predict the theoretical visual detection distance of a target in water from the rate of reduction in its contrast with the water background. Experiments were conducted at three field sites to compare the predicted distances for gray tiles of different reflectance with those obtained from human observers. The predictions were relatively accurate in water having a low light-scattering component and when the predictions were based on visual estimates of contrast (rather than on photometric measurements). Data for water with a high degree of scatter call into question the indiscriminate application of a visibility model derived from the contrast reduction equation.
Optimal Colors, Phosphors, and Illuminant Characteristics for CRT Displays: The Algorithmic Approach
Authors: Corte Wilfried De
Published: July 2017

A new strategy for the determination of optimal colors, phosphors, and surrounding ambients for CRT displays is outlined: the algorithmic approach. This approach enables the display manufacturer and the designer of display layouts to compute sets of highly contrasting colors that optimally implement both the possibilities of the CRT device and the findings from vision and human factors research. The resulting COLSET algorithm is the first one to estimate simultaneously the parameter sets related to the phosphor luminances, the phosphor chromaticities, and the chromaticity of an additional illuminant. COLSET is also the first method that allows for a restricted optimization of these parameters. A number of pilot applications illustrate the possibilities of the algorithm and compare the method with existing approaches. Guidelines are presented for the implementation of the algorithmic approach in research and applied settings.
The Effects of Set Size on Color Matching Using CRT Displays
Authors: Luria S. M. , Neri David F. , Jacobsen Alan R.
Published: July 2017

The time required to match a colored stimulus to one of a set of colors was measured as a function of color sets ranging in size from 2 to 10. Reaction time (RT) increased linearly with increases in set size to 5 or 6, after which the increase, although still linear, was less steep. Error rate increased sharply with set sizes of 8, 9, and 10. The relative RTs to the different colors remained constant despite changes in the experimental method.
Reading from Microfiche, a VDT, and the Printed Page: Subjective Fatigue and Performance
Authors: Cushman William H.
Published: July 2017

Subjects read continuous text for 80 min using microfiche and video display terminals (VDTs) with negative- and positive-appearing images and printed paper copy. Measurements of visual fatigue (ocular discomfort) and reading speed were obtained periodically, and a test of reading comprehension was given at the end of each session. Visual fatigue was significantly greater when subjects read from negative microfiche (light characters, dark background) projected on a metal screen or from the screen of a VDT with positive-appearing images (dark characters, light background). However, when subjects read from microfiche projected on a high-reflectance matte screen or from the screen of a VDT with negative images, visual fatigue was not significantly greater than that reported for the printed materials. Reading speeds tended to be slower for the negative image conditions. but reading comprehension scores were similar for all conditions.
Effect of Visual Display Scale on Duration Estimates
Authors: Bobko Douglas J. , Bobko Philip , Davis Mark A.
Published: July 2017

Duration estimation is shown to be affected by the scale, or size, of visual displays. In particular, verbal estimates of the duration of a fixed interval of time tend to increase as the size of a given visual display decreases. The results are considered from two general theoretical frameworks (psychobiological chronometer and information storage-size theories).
Does Visual Angle of a Line of Characters Affect Reading Speed?
Authors: Gould John D. , Grischkowsky Nancy
Published: July 2017

Eighteen participants each proofread 12 three-page articles. Each article was printed at six sizes (or scales) and in two different character sets. Reading distance was constant (52 cm). The lines of characters on the pages subtended 6.7, 10.6, 16.0, 24.3, 36.4, and 53.4 deg at a participant's eye. Proofreading speed and accuracy were reduced at the extreme visual angles. Within a range of at least 16 to 36 deg, proofreading speed and accuracy were unaffected. The significance of these findings is that people's reading efficiency is invariant over a large range of normal viewing. Most printed text and text shown on computer terminal screens form visual angles within this range. Therefore, differences in visual angle probably do not account for the slower reading speed found when people read from CRT displays than from paper (Gould and Grischkowsky, 1984).
Some Comparisons of Characteristics of Alphabetic Codes for the Deaf-Blind
Authors: Thurlow Willard R.
Published: July 2017

Several alphabet codes for the deaf-blind were compared with respect to tactual discriminability and ease of code learning, utilizing subjects with normal vision and hearing. Results can suggest ways for improving codes used by the deaf-blind. Among raised-print codes (typically used for reading), Braille was found to be difficult both to learn and to discriminate tactually. The Moon code was found to be significantly less difficult than Braille. Although raised capital letters are difficult to recognize tactually, modifications of the letters can be made (NL code) that can make them much more easily recognized. Code size and direction of scan (vertical versus horizontal) were significant determinants of discriminability of raised-print symbols. Among hand-sent codes for person-to-person communication, hand-printed letters in the palm were well discriminated. For individuals with no experience with visual letter forms or who have trouble discriminating complex tactual symbols, a simple tactual finger code (T code) offers a solution. The T-code symbols are easy to discriminate and to learn.
Comparison of Maximum Volitional Torque Exertion Capabilities of Males and Females Using Common Hand Tools
Authors: Mital Anil , Sanghavi N.
Published: July 2017

This study examines the effects of several operator- and task-related variables, defining the operator hand-tool system at the workplace, on peak volitional torque exertion capabilities of males and females with common nonpowered handtools. Maximum volitional torque was measured on 55 adult subjects (30 male, 25 female) in 540 treatment combinations (5 Tools x 2 Postures x 3 Heights x 3 Reach Distances x 6 Angles). Results of the study indicated that peak torque exertion capabilities of females average 66% of the male torques. Means for height and angle, although statistically different, had little practical difference. The major differences were in type of hand tool (30 kg-cm for screwdrivers versus 246 kg-cm for wrenches), posture (140 kg-cm for sitting versus 175kg-cm for standing), and reach distance (185 kg-cm at a distance of 33 cm versus 131 kg-cm at a distance of about 71 cm). Some of the task variable interactions were also significant. Among the various isometric strength and anthropometric variables, isometric shoulder strength was most important and appeared to limit the torque exertion capability of individuals. Peak torque profiles of males and females using common nonpowered handtools are presented.
The Validity of Subjective Reports of Visual Discomfort
Authors: Howarth Peter Alan , Istance Howell Owen
Published: July 2017

Many surveys comparing users of visual display units with non-users have evaluated discomfort with a single questionnaire, designed to determine the occurrence of various symptoms. These in reality elicit the person's opinion or recollection of their discomfort rather than its actual frequency or severity. To examine the validity of this measure for intergroup comparisons, we administered a questionnaire of this type and then determined the incidence of a number of symptoms over a working week. We examined four different work groups and found that, after subjects had been matched for their questionnaire report, there were significant differences in the amount of discomfort reported. This between-groups difference in reporting behavior may account for some reports that VDU users suffer more discomfort than do non-users.
Noise and Vigilance: An Evaluative Review
Authors: Koelega Harry S. , Brinkman Jan-Albert
Published: July 2017

The literature on the effects of noise on monitoring performance shows a disappointing lack of consistency in results. The hypothesis of the present study was that task classification in terms of demands made on the observer should reconcile conflicting findings so that generalizations could be made. Therefore, a study was made of the effects of intermittent or variable noise on vigilance experiments with similar task demands. Twenty-one sensory vigilance studies, selected from 98 visual performance experiments, were analyzed in detail. It appeared that, even when studies possess similar task characteristics, they are hard to compare due to the many types and varieties of the noise variables involved and the measures of performance used. Contradictory results remain. It was concluded that we know nothing about the effects of variable noise on sustained attention, despite the importance of this kind of noise for everyday life. Using this detailed analysis as an illustration, it was suggested that disparate task definitions contribute to variable or inconsistent results in vigilance, and that it does not make sense to search for the effect of independent variables on “vigilance.” The usefulness of future reviews of “noise and vigilance,” as well as of “the effects of noise,” and the results of “vigilance tasks” were questioned.
The Effects of Pavement Edgelines on Performance in a Driving Simulator under Sober and Alcohol-Dosed Conditions
Authors: Ranney Thomas A. , Gawron Valerie J.
Published: July 2017

To identify the impairment effects of alcohol on driving performance and to determine whether providing enhanced visual information concerning roadway alignment would improve the performance of subjects when sober and/or alcohol-dosed, simulations of continuous roadway treatments (i.e., standard and wide edgelines) were evaluated experimentally. Twelve subjects drove a simulator at three levels of blood alcohol concentration (BAC: 0.00%, 0.07%, 0.12%). The effects of alcohol included increases in the number of times the speed limit was exceeded, the number of obstacles that were struck, and the magnitude of tracking errors that were made in the approach and negotiation of curves. Edgeline presence was associated with faster curve entry speeds and reduced amount of road used in curve negotiation, both interpreted as positive effects. Additional benefits associated with wide edgelines were minimal.
Task Complexity in Visual Inspection
Authors: Gallwey T. J. , Drury C. G.
Published: July 2017

Three types of inspection complexity were tested on an inspection task using both industrial and student subjects. Items inspected varied with regard to the number of different fault types (two, four, or six), whether the inspecting standards for each fault type were the same or different, and whether faults occurred anywhere on the item or only on specific sub-areas. Number of fault types had a large effect on the search component of the task. The effect of same or different standards was largely confined to the decision-making component. There was no effect of faults being distributed across the whole or part of the item. The 18 industrial quality-control personnel were not significantly different in performance from the 48 student subjects tested.
The Detection and Localization of Objects by the Blind with the Aid of Long-Cane Tapping Sounds
Authors: Schenkman Bo N. , Jansson Gunnar
Published: July 2017

The aim of the investigation was to study the usefulness of long-cane tapping sounds for echolocation by blind people. Ten long canes that differed in the spectra of their tapping sounds were selected for the experiment. The task of the three blind subjects when walking was first to detect an object and then to localize it more precisely. The following results were obtained. (1) Objects could be detected and localized with the aid of the long-cane tapping sound alone, but the task was difficult. (2) The results varied with the size of the object. (3) Differences in the spectra of tapping sounds had no behavioral effects.
Effects of Side-Impact Padding on Driver Performance
Authors: Gawron Valerie J. , Baum A. Stephen , Perel Michael
Published: July 2017

Recent research has indicated that the best method of protecting vehicle occupants in side impacts is to provide as much energy-absorbing padding as possible between the occupant and the side-door panel. On the driver's side of the vehicle, however, it is essential that the driver's ability to control the automobile not be degraded. Two experiments were undertaken to design and evaluate an acceptable side-door panel for a compact vehicle. Once a padding design has been determined, other studies can define the appropriate energy-absorbing materials and the panel's injury-mitigation potential. In Experiment I, driver arm movements and, hence, lateral-clearance requirements were defined from driving data. Based on these requirements, a candidate side-panel interior padding was designed. During Experiment 2, the effects of candidate door panels on driver performance were evaluated in a closed-course experiment. The results indicated a statistically significant increase in time required to complete a lane change as padding thickness increased.
Modeling Fault Diagnosis as the Activation and Use of a Frame System
Authors: Smith Philip J. , Giffin Walter C. , Rockwell Thomas H. , Thomas Mark
Published: July 2017

Twenty pilots with instrument flight ratings were asked to perform a fault-diagnosis task for which they had relevant domain knowledge. The pilots were asked to think out loud as they requested and interpreted information. Performances were then modeled as the activation and use of a frame system. Cognitive biases, memory distortions and losses, and failures to correctly diagnose the problem were studied in the context of this frame system model.
Content, Variety, and Augmentation of Simulated Visual Scenes for Teaching Air-to-Ground Attack
Authors: Lintern Gavan , Thomley-Yates Karen E. , Nelson Brian E. , Roscoe Stanley N.
Published: July 2017

The Visual Technology Research Simulator was used for a quasi-transfer-of-training study in which 32 military pilots were taught to deliver bombs from a 30-deg dive. Scene content had a strong and consistent effect on performance and on differential transfer. A landscape scene that contained buildings, roads, and rectangular fields was better than a schematic grid pattern for both training and transfer. Scene variety in training did not benefit transfer, and there is a distinct possibility that it can interfere with early learning. Augmented feedback proved to be a potent instructional variable, but one that showed complex effects. It helped inexperienced pilots with their dive pitch control, and it helped the more experienced pilots with their longitudinal bombing error. The data presented here have strong implications for design and use of flight training simulators in that they indicate the importance of scene content and augmented feedback as training variables.
Dreams-Design and Destiny
Authors: Hornick Richard J.
Published: July 2017

Humankind's dreams of progress result in creative and increasingly complex technological wonders. But dreams often turn to nightmares. The attitudinal and organizational causes of several tragedies are explored, and a management and design attitude expressed by Petroski (1985) is examined as illustrative of these causal factors. Liability in courts of law is suggested as society's conscience mechanism for correction, and a challenge to the human factors profession is expressed.
Changes in Electromyographic Activity Associated with Occupational Stress and Poor Performance in the Workplace
Authors: Gomer Frank E. , Silverstein Louis D. , Berg W. Keith , Lassiter Donald L.
Published: July 2017

A shift in the power spectrum of surface electromyographic (EMG) activity, recorded during machine-paced keyboard operation and indicative of localized muscle fatigue in the forearms, clearly distinguished two groups of operators who sorted mail in accordance with different work practices. The group exhibiting these fatigue-related changes in EMG activity also (1) had much greater difficulty in meeting the accuracy requirements of the keyboard function; (2) rated visual, mental, and keying-related workload as objectionably high; (3) exhibited greater tremor in a post-work test of hand steadiness; and (4) reported greater physical discomfort in the fingers, hands, wrists, and arms. These results demonstrate that physiological data can increase our understanding of the effects of occupational stress on performance in the workplace.
A Psychophysiological Assessment of Operator Workload During Simulated Flight Missions
Authors: Kramer Arthur F. , Sirevaag Erik J. , Braune Rolf
Published: July 2017

Previous research has indicated that components of the event-related potential (ERP) may be used to quantify the resource requirements of complex cognitive tasks. The present study was designed to explore the degree to which these results could be generalized to complex, real-world tasks. The study also examined the relations among performance-based, subjective, and psychophysiological measures of operator workload. Seven male volunteers, enrolled in an instrument flight rule (IFR) aviation course at the University of Illinois, participated in the study. The student pilots flew a series of IFR flight missions in a single-engine, fixed-based simulator. In dual-task conditions subjects were also required to discriminate between two tones differing in frequency and to make an occasional overt response. ERPs time-locked to the tones, subjective effort ratings, and overt performance measures were collected during two separate 45-min flights differing in difficulty. The difficult flight was associated with high subjective effort ratings, as well as increased deviations from the command altitude, heading, and glideslope. The P300 component of the ERP discriminated among levels of task difficulty, decreasing in amplitude with increased task demands. Within-flight demands were examined by dividing each flight into four segments: takeoff, straight and level flight, holding patterns, and landings. The amplitude of the P300 was negatively correlated with deviations from command headings across the flight segments. In sum, the findings provide preliminary evidence for the assertion that ERP components can be employed as metrics of resource allocation in complex, real-world environments.
The Spatial Allocation of Visual Attention as Indexed by Event-Related Brain Potentials
Authors: Mangun G. R. R. , Hillyard S. A.
Published: July 2017

The spatial distribution of visual attention was studied using event-related brain potentials (ERPs) to index stimulus processing as the locus of attention was shifted across the visual fields. Stimuli were flashed in random order to one of three locations: one in each of the lateral visual fields and one on the vertical meridian. Selective visual-spatial attention was manifested in the ERPs as an amplitude modulation of the sensory-evoked components over frontal, central, parietal, and occipital scalp areas. Attended stimuli also elicited broader negative components that appeared to be endogenous and could be dissociated from the amplitude enhancement of the earlier sensory-evoked components. A gradient of attention was evident in the progressive decline in amplitude of the sensory-evoked components of the ERPs to the lateral stimuli as attention was focused at increasing distances from the stimulus location. These results are discussed in terms of “spotlight” and “gradient” models of the spatial allocation of visual attention.
Part-Task Training Strategies in Simulated Carrier Landing Final-Approach Training
Authors: Wightman Dennis C. , Sistrunk Frank
Published: July 2017

An investigation of the impact of part-task training strategies on transfer to simulated carrier landing was conducted in a simulator. College students were taught carrier landing final-approach skills in the simulator under a control or one of three experimental training conditions, and were then tested in the simulator on a criterion configuration that was identical to the control training condition. A task segmentation training strategy (chaining) and a task simplification training strategy (enhancement of the simulated aircraft's response to throttle adjustments) were tested. In addition, the subjects' motor-skill aptitudes were assessed using a video game that has previously been shown to correlate with simulated carrier landing performance. Training under backward procedures of chaining produced better transfer to the criterion task than did an equal number of training trials on the criterion task itself. An interaction between aptitude and treatment indicated that the chaining method of training was particularly advantageous for low-aptitude subjects. The simplification strategy did not appear to enhance transfer.