bluuebunny/crossref_metadata_2025 huggingface dataset:
Tangible Line Graphs: An Experimental Investigation of Three Formats Using Capsule Paper
Authors: Aldrich Frances K. , Parkin Alan J.
Published: July 2017

This study explores three formats for the presentation of tangible line graphs to visually handicapped people, using the capsule-paper production process. The formats are L/no-grid (standard x and y axes/data curves on smooth background), box/no-grid (duplicated axes enclose graph space on all four sides/smooth background), and box/grid (duplicated axes/data curves superimposed on grid). Subjects answered questions concerning the coordinate value of points, the difference in coordinate value between two points, and configurational aspects of the data. Questions that involved determining coordinate values were answered most accurately from the box/grid format, followed by the box/no-grid, and, lastly, the L/no-grid. Response times did not differ. A different pattern emerged with questions concerning configurational aspects of the graph. With these there was no difference in accuracy between the formats, but the L/no-grid format led to faster responding than the box/no-grid, which in turn was faster than the box/grid. The practical implications of these data are considered.
Assaying and Isolating Individual Differences in Searching a Hierarchical File System
Authors: Vicente Kim J. , Hayes Brian C. , Williges Robert C.
Published: July 2017

Individual differences among users of a hierarchical file system were investigated. Results indicate that psychometric tests of vocabulary and spatial visualization are the best predictors of task performance, accounting for 45% of the variance in the data. The spatial predictor was found to be the most influential. This was dramatically illustrated by the fact that, on the average, subjects with low spatial ability took twice as long to perform the task as those with high spatial ability. Surprisingly, experience alone does not predict task performance. A comparison of the frequency of command usage between subjects with high and low spatial ability revealed that those with low spatial ability were getting lost in the hierarchical file structure. These data have implications for redesigning the software interface so as to accommodate people with low spatial ability.
Display Formatting in Information Integration and Nonintegration Tasks
Authors: Boles David B. , Wickens Christopher D.
Published: July 2017

The impact of various formats used in the design of visual displays was investigated in two reaction-time (RT) experiments. Analog, digital, and verbal formats were employed with numerical judgment tasks requiring either the integration or non integration of display elements. As predicted by multiple resource theory, the dual task (nonintegration) benefited from a mixed-format display. Integration tasks, however, revealed a contrasting benefit of pure-format displays. Generally speaking, analog indicators were responded to more quickly than were digital or verbal indicators. Three guidelines for display design are suggested.
Models of Procedural Control for Human Performance Simulation
Authors: Sticha Paul J.
Published: July 2017

This paper describes and evaluates two general techniques to simulate human performance of procedural tasks. A procedural task is characterized as a partial ordering of task elements in which the control of task-element sequencing is represented within the task, rather than as an interaction between the task and the environment in which the task is performed. The primary concern in simulating the performance of procedures is determining the mechanism that controls task-element sequencing. Two modeling frameworks have been used to represent task-element sequencing. The first method represents the constraints on task-element sequencing directly in a network. Am second method represents sequencing constraints indirectly as a set of production rules. Both frameworks offer considerable generality and flexibility in the kinds of structures that can be represented. The relative advantages of the two methods depend upon the questions addressed by the model and the characteristics of the tasks being modeled.
Effect of Pixel Height, Display Height, and Vertical Resolution on the Detection of a Simple Vertical Line Signal in Visual Noise
Authors: Moulden Bernard , Kingdom Fred
Published: July 2017

Spatial resolution is one of the parameters that engineers designing digital displays must consider. Three experiments are described that investigate the effects of vertical spatial resolution and the interrelated parameters, pixel height and display height, on the visibility of straight vertical line signals in visual noise. A signal detection analysis of the results showed that detection efficiency was unaffected by vertical resolution and pixel height, whereas an increase in display/signal height resulted in a decline in efficiency. The decline is attributed to the increasing difficulty the visual system encounters when integrating luminance over an increasing spatial extent. It is suggested that in practical digital displays of the kind described here, pixels should be as short as possible in order that the available display information be compressed into the smallest possible height.
Temporal Resolution: An Insight into the Video Display Terminal (VDT) “Problem”
Authors: Harwood Kelly , Foley Patrick
Published: July 2017

Previous studies suggest that many of the discomforts associated with VDT use may be attributed to poor working conditions and to the task itself However, the relationship between visual complaints and specific display characteristics of the VDT is not entirely clear. This study investigated the effect of the temporal characteristics of VDT display luminance on temporal resolution of the visual system. Subjective ratings of visual discomfort and task performance were also considered. Ten individuals performed a visual search task for three hours at either a VDT display or back-projection display system. The only difference between these two displays was the temporal characteristics of display luminance. Environmental factors were equated for both conditions. Despite the similarity between conditions, temporal resolution decreased over time and individuals reported increased task difficulty, difficulty in concentrating, tired eyes, and the need to shut eyes more often for VDT use.
Alternative Option Selection Methods in Menu-Driven Computer Programs
Authors: Shinar David , Stern Helman I.
Published: July 2017

In menu-driven computer programs the user is often required to select an option from among several alternatives. The most common response system for this selection is the standard keyboard. Three response selection methods were evaluated: using a key-controlled cursor to point to the desired option, keying a digit to indicate the desired option, and keying a letter that served as a mnemonic device. The speed and errors of selecting options with the alternative methods were studied as a function of (1) the number of the alternative options in the array and (2) familiarity with the program and the options. Results demonstrated the superiority of the meaningful letter code, and the differential and lower effectiveness of cursor and digit as a function of level of practice and number of options. A default selection method that utilizes the practice effect is recommended.
Review and Evaluation of Physiological Cost Prediction Models for Manual Materials Handling
Authors: GENAIDY A. M. , ASFOUR S. S.
Published: July 2017

Manual materials handling (MMH) tasks or unaided acts of lifting, lowering, carrying, pushing, and pulling are common types of activities in industry. Design and organization of work involving manual handling of materials has been the goal of many researchers. Their attempts have resulted in information that can be objectively used in designing manual materials handling tasks. The main objectives of this paper are (1) to review and evaluate existing energy and cardiac cost prediction models for various MMH tasks, (2) to present these models in a concise fashion that can be easily accessed by designers and practitioners of MMH, and (3) to provide recommendations for future research in modeling physiological responses of individuals engaged in MMH. More emphasis is placed on information that has become available since the publication of the NIOSH guide on work practices for Manual lifting.
A Two-Term Exponential Functional Description of the Time Course of Sustained Attention
Authors: Giambra Leonard M. , Quilter Reginald E.
Published: July 2017

A consensus of critical reviews of single-process theories of vigilance or sustained attention has supported the view that the vigilance decrement must be the result of two or more coacting or interacting processes or systems. One theoretical position, as well as the ubiquity of exponential functions in characterizing the time course of biological processes, led to the hypothesis that the time course of sustained attention could be best modeled by the function

A[e-T1-time 11(1 + eT2*time)].

An experimental test (n = 613) using 23 points showed that this function accounted for 96.7% of the variance of detection accuracy and was 1.2 times better than a previously proposed single-term model. All parameter estimates were highly statistically significant. Fits to data from three other studies also supported the two-term exponential model. The model fitted target response time less well, accounting for 75.6% of the variance.
Limitations of the Cognitive Vigilance Increment
Authors: Loeb Michel , Noonan Thomas K. , Ash Dan W. , Holding Dennis H.
Published: July 2017

This paper contrasts the positive evidence for a cognitive vigilance increment with several unsuccessful attempts at replication and reports three further experiments. Experiment 1 employs six different levels of task complexity involving the use of auditory cues, finding a weak overall decrement over time. Experiment 2 obtains similar results using the original simple and complex tasks in conditions of cuing. Experiment 3 compares three uncued conditions, finding a slight improvement in response times on the most complex task. Reviewing the evidence suggests three groups of reasons for nonreplication: differences in tasks and presentation variables, possible sex differences, and the presence of cue tones. Making allowance for these variables, it is concluded that fixed-range tasks produce an increment whereas variable-range tasks do not, although all the cognitive versions are relatively resistant to decrement.
Application of Vigilance Research: Rare, Medium, or Well Done?
Authors: Wiener Earl L.
Published: July 2017

Despite a history of over 40 years and a vast amount of experimentation, vigilance research has not had a palpable impact on real-world systems. The problem has been blamed in part on the types of studies and the range of variables that have been chosen, but this is only part of the picture. The failure of implementation can also be attributed to insufficient interest in bridging the gap between the laboratory and the work world and lack of data from not the former but the latter. The situation will probably remain unremedied until more effort is made to understand the nature of complex systems and their dependence on human monitors and until the myth that automation of functions eliminates or even diminishes the need for human vigilance is abandoned.
Criticisms of Vigilance Research: A Discussion
Authors: Adams Jack A.
Published: July 2017

There have been two major criticisms of research on vigilance decrement: (1) that there are few troublesome decrements in the real world and (2) that laboratory research on vigilance, often done with comparatively simple tasks, generalizes poorly to complex tasks in operational situations. The first criticism is supported by research that has failed to find vigilance decrement in operationally relevant situations. The second criticism involves the relationship between basic and applied research. Applied scientists who face immediate practical problems should solve them with quasi-realistic simulation. Simulation-based research has limited generality, however, and should not be seen as a substitute for more general solutions that come from basic research and the variables and laws that it establishes.
Display Proximity in Multicue Information Integration: The Benefits of Boxes
Authors: Barnett Barbara J. , Wickens Christopher D.
Published: July 2017

This study investigates the ability of an individual to integrate probabilistic information from a number of sources, and focuses particularly on the extent to which this integration is influenced by display proximity in space, time, and object configuration. In support of the principle of compatibility of proximity, the data indicated that integration performance was clearly ordered according to the degree of display integrality: those in the more integral rectangle conditions were significantly better at integration than those in the bar graph condition. Proximity of space had little effect upon performance, whereas proximity in time significantly improved performance in all three format conditions. Speed stress significantly hindered performance in all three format conditions. Finally, memory for isolated unintegrated attributes of a cue was not harmed by the increasing integrality of the rectangle formats.
Evaluation of Powered Screwdriver Design Characteristics
Authors: Johnson Steven L.
Published: July 2017

This study investigated the physical characteristics of powered screwdrivers that affect the operator's productivity, occupational health, and quality of working life. The study was divided into two phases. The first phase evaluated the effect of grip diameter on the effort required to use the tool. The second phase evaluated two devices that can be attached to the tool and are intended to reduce operator effort and the potential for injury. The results illustrated that the diameter of the grip has an influence on the operator. The recommendations are counter to the common assumption made by industrial tool engineers that smaller tools are easier on the user. The results of the second phase illustrated that the tool attachments have merit with respect to the reduction of operator effort. The conclusions are important for both designers and users of powered tools.
Predictive Models of Upper Extremity Rotary and Linear Pull Strength
Authors: Imrhan Sheik N. , Ayoub Mohamed M.
Published: July 2017

Regression models were developed to predict linear isokinetic pull strength of the upper extremity from rotary isokinetic strengths about the elbow and shoulder and other related factors. Data on linear pull strength were gathered and analyzed to determine levels of factors appropriate for measuring isolated joint rotary strengths—elbow flexion and shoulder extension. Data on these rotary strengths were then gathered and used to develop predictive models for peak elbow flexion and peak shoulder extension forces. Using these models and the pull-strength data, other models were finally developed for predicting peak linear pull force. The data from seven subjects were used to develop the models, which were validated by data from three other subjects. All contractions were maximal voluntary ones, and only peak torques were analyzed. Subjects were always seated during strength testing.
Spatial Requirements for Visual Simulation of Aircraft at Real-World Distances
Authors: Kennedy Robert S. , Berbaum Kevin S. , Collyer Stanley C. , May James G. , Dunlap William P.
Published: July 2017

To provide target image sufficiency guidelines for ground-based flight training simulators, a detection experiment examined the relative effects of contrast, resolution, and brightness on the simulated distance at which subjects could determine the orientation of another aircraft. With high resolution, luminance contrast of 25:1 produced better performance than lower contrasts. The performance at the best contrast condition was 40% better than at the poorest, whereas the best resolution condition produced only 20% better performance than the poorest. In three identical contrast conditions, higher luminance levels results in slightly better performance. In the best experimental condition, average aspect recognition thresholds for the TA-41 aircraft occurred at simulated distances > 4 miles (6.44 km), whereas in the most degraded condition, average thresholds occurred at simulated distances of 1.5 miles (2.415 km).
Counting, Computing, and the Representation of Numbers
Authors: Nickerson Raymond S.
Published: July 2017

How easy it is to manipulate numbers depends in part on how they are represented visually. In this paper several ancient systems for representing numbers are compared with the Arabic system, which is used throughout the world today. It is suggested that the Arabic system is a superior vehicle for computing, largely because of the compactness and extensibility of its notation, and that these features have been bought at the cost of greater abstractness. Numbers in the Arabic system bear a less obvious relationship to the quantities they represent than do numbers in many earlier systems. Moreover, the elementary arithmetic operations of addition and subtraction are also more abstract; in some of the earlier systems the addition of two numbers is similar in an obvious way to the addition of two sets of objects, and the correspondence between subtraction with numbers and the subtraction of one set of objects from another is also relatively direct. The greater abstractness of the Arabic system may make it somewhat more difficult to learn and may obscure the basis for such elementary arithmetic operations as carrying and borrowing. The power of the system lies in the fact that once it has been learned, it is the most efficient of any system yet developed for representing and manipulating quantities of all magnitudes.
Human Performance Evaluation of Digitizer Pucks for Computer Input of Spatial Information
Authors: Rosenberg Daniel J. , Martin Gale
Published: July 2017

Two experiments were performed to measure and find ways of improving the accuracy with which people can enter spatial coordinates into a computer with a digitizer puck. A digitizer puck is similar to a mouse; however, rather than serving to position a cursor on a display screen, the puck is used to enter the spatial coordinates of points in a hard-copy document such as a map, photograph, or image representation of text. The first experiment studied the effect of the type of optical sight provided on the puck. The second experiment examined the effect of using a 2.5-power magnifier. Varying the type of optical sight used did not affect accuracy, but use of the magnifier did significantly improve accuracy. The study also suggested some initial estimates of the accuracy levels obtainable by most people. Most of the subjects were accurate to within ± 0.125 mm to ± 0.250 mm of the true target position. Magnification drives the error value down to the lower ends of this range.
Strategic Issues in Knowledge Engineering
Authors: Chignell Mark H. , Peterson James G.
Published: July 2017

Expert systems should find widespread application in human factors, provided the problem of building expert systems (knowledge engineering) is dealt with satisfactorily. The task of knowledge engineering is outlined and five key strategic issues are identified. These strategic issues are discussed from a human factors perspective, and it is shown how current knowledge engineering methods can be extended to include the concerns of human factors. The potential contribution of human factors to knowledge engineering methodology is illustrated with two examples. The first shows how ranking techniques can be adapted to meet the requirements of knowledge elicitation; the second shows how protocol analysis can be used to validate expertise.
Likelihood Alarm Displays
Authors: Sorkin Robert D. , Kantowitz Barry H. , Kantowitz Susan C.
Published: July 2017

In a likelihood alarm display (LAD) information about event likelihood is computed by an automated monitoring system and encoded into an alerting signal for the human operator. Operator performance within a dual-task paradigm was evaluated with two LADs: a color-coded visual alarm and a linguistically coded synthetic speech alarm. The operator's primary task was one of tracking; the secondary task was to monitor a four-element numerical display and determine whether the data arose from a "signal" or "no-signal" condition. A simulated "intelligent" monitoring system alerted the operator to the likelihood of a signal. The results indicated that (1) automated monitoring systems can improve performance on primary and secondary tasks; (2) LADs can improve the allocation of attention among tasks and provide information integrated into operator decisions; and (3) LADs do not necessarily add to the operator's attentional load.
Performance Measurement during Simulated Air-to-Air Combat
Authors: Kelly Michael J.
Published: July 2017

Measurement and assessment of operator performance of complex tasks with decisional and psychomotor components of which only ultimate outcome measures are well defined provide difficult methodological challenges. One such task is the practice of air-to-air combat skills in simulated combat environments such as the Air Force Air Combat Maneuvering Instrumentation (ACMI) or ground-based visual flight simulators. Measurement and assessment of pilot performance in these environments are especially challenging because of the special cognitive and psychomotor skills involved in the freeplay and gamesmanship of two or more competing pilots. A review of the existing approaches to automated aircrew performance measurement was performed. Although the most common measurement models, using positional advantage or disadvantage, provide an adequate performance metric, other measures, such as control manipulation and the management of kinetic and potential energy, must be added to provide a refined performance measurement algorithm.
Examination of the Role of “Higher-Order” Consistency in Skill Development
Authors: Fisk Arthur D. , Oransky Natalie A. , Skedsvold Paula R.
Published: July 2017

Three experiments examined the importance of “higher-level” consistencies---consistency not defined by the individual stimuli themselves but by the relationships among stimuli. In the first experiment subjects made either a consistent or a varied decision concerning the ordinal value of numbers in a display. The second experiment used stimuli that had no pre-experimental relational ordering (symbols such as @ or #) to examine the development of this relational learning. Half of the subjects made consistent decisions and half made inconsistent decisions. The final experiment tested the importance of consistent relationships by randomly ordering the symbols on each trial. The experiments demonstrate that subjects can develop performance indicative of automatic processing if the relationships among stimuli remain consistent. Decision consistency is most important for stimuli possessing well-learned relationships. The importance of the data revolve around a determination of what can become automatic, the development of an extended definition of consistency, and an understanding of what may be the “learning unit” in complex real-world tasks.
The Effects of Preview and Task Symmetry on Trunk Muscle Response to Sudden Loading
Authors: Lavender Steven A. , Mirka Gary A. , Schoenmarklin Richard W. , Sommerich Carolyn M. , Sudhakar L. R. , Marras William S.
Published: July 2017

The effect of warning time (preview) and task symmetry on the trunk muscular response to sudden loading conditions was investigated. Eleven subjects were asked to catch falling weights with four levels of preview (0, 100, 200, and 400 ms) in sagittally symmetric posture and asymmetric posture. For each of the eight muscles sampled with surface electrodes, the integrated electromyographic (EMG) signal was interpreted in terms of its peak value, mean value, onset rate, and lead/lag time with reference to the weight drop. Results show linear relationships between preview times and peak EMG, preview times and mean EMG, and preview times and lead times. The results show significant change when going from symmetric to asymmetric conditions across most dependent measures. Analysis of peak changes in compression were performed across all conditions but yielded unexpected results.
The Acoustic Startle Response and Disruption of Aiming: I. Effect of Stimulus Repetition, Intensity, and Intensity Changes
Authors: Foss John A. , Ison James R. , Torre James P. , Wansack Samuel
Published: July 2017

Three experiments examined the disruption of perceptual motor performance by intense noise bursts. Subjects aimed a rifle at a fixed target for 15-s periods separated by 15 s of rest. This cycle was repeated 30 times in each of two series separated by a 15-min rest, each series containing five noise bursts. The noise bursts disrupted aiming for 1—2 s, an effect that increased with sound pressure level for 110, 120, and 130 dB stimuli. There was no difference between stimuli with energy centered on 250 Hz as opposed to 800 Hz. The effect diminished over the five bursts within the first series (but not to zero) and did not recover in the 15-min rest period. Some subjects received three days of testing; in these cases the effect of the noise bursts partially recovered after rest intervals of 24 hrs and then seven days. Other subjects received 15 trials with 110-dB stimuli, then five more trials with 130-dB stimuli. The disruption of aiming by 130 dB stimuli was not reduced by prior exposure to 110-dB stimuli.
The Acoustic Startle Response and Disruption of Aiming: II. Modulation by Forewarning and Preliminary Stimuli
Authors: Foss John A. , Ison James R. , Torre James P. , Wansack Samuel
Published: July 2017

Four experiments examined the disruption of rifle aim by intense noise bursts. In Experiment 1 a trigger pull was followed occasionally by a noise burst. Aiming was disrupted for 1—2 s, an effect that habituated within days and recovered between days. Expected stimuli were less disruptive than were unexpected stimuli. Experiment 2 demonstrated that weak auditory prestimuli 100 ms before unexpected intense sounds also reduced noise-produced errors. Experiment 3 showed that the intratympanic reflex had not played a protective role in this effect. Experiment 4 showed that a weak tactile prestimulus increased both a muscular measure of the acoustic startle reaction and the perturbing effect of the noise burst on motor performance. In general, conditions that affect the amplitude of the acoustic startle reflex similarly influence the disruptive effect of a noise burst on motor performance, but the two measures are not correlated in the detail necessary to suggest a causative relationship.
An Experimental Analysis of Railroad Spike Maul Methods
Authors: Gray Beth A. , Marras William S.
Published: July 2017

This study investigated differences in railroad spike maul methods between experienced track workers and novice subjects. Differences were analyzed by developing a quantitative measure of the orientation of the spike maul path during spiking. The relationship between spiking motion pattern and spiking performance in both novice and experienced subjects was also investigated. Subjects were videotaped while using a spike maul on an instrumented spike force measuring system. Analysis of videotapes and performance measures revealed significant differences in motion patterns and performance between novice and experienced subjects. It was concluded from analysis of spike maul motion patterns that experienced track workers had developed a more efficient ballistic technique than had novices. This technique was evidenced by positioning of the maul close to the body's center of gravity, flexing the elbows, and using wrist motion on the downswing.
Unintended Acceleration: A Review of Human Factors Contributions
Authors: Schmidt Richard A.
Published: July 2017

The evidence is reviewed for a human factors explanation of the phenomenon of unintended acceleration, whereby at the start of a driving cycle an operator experiences full, unexpected acceleration for as long as 12 s with an apparently complete failure of the braking system, often leading to an accident. There is strong support for the view that the right foot contacts the accelerator even though the driver fully intended to press the brake because of inconsistency in foot trajectory generated by spinal- or muscle-level variability. There is considerable evidence that the variable, inconsistent processes that generate muscular forces and their timing are the source of these errors. Issues related to the reasons the driver is not aware of such errors and why they can persist for so long are reviewed. In view of this evidence, future examinations of this problem should be directed toward a fuller understanding of motor control processes in pedal operation.
Enhanced Detection with Bimodal Sonar Displays
Authors: Doll Theodore J. , Hanna Thomas E.
Published: July 2017

Signal-to-noise ratios (SNRs) required to detect narrow-band signals in white noise were compared for bimodal and single-modality sonar displays at two levels of signal uncertainty and two degrees of spatial compatibility between the auditory and visual displays. In bimodal test conditions the auditory and visual signals were equated in detectability for each subject. An adaptive, two-alternative, forced-choice procedure was used to maintain a constant percentage of correct responses. The decrement in performance with increased signal uncertainty was significantly greater for visual than for auditory displays, suggesting that auditory displays offer advantages for real-world sonar operations. Bimodal displays produced a reliable advantage in SNR required for detection over single-modality displays. Increased compatibility between the visual and auditory displays did not increase the advantage of bimodal presentation, nor did increased signal uncertainty. It was concluded that bimodal displays enhance operators' perceptual sensitivity. The magnitude of the enhancement was consistent with optimal integration of information in the two modalities.
The Human Planning and Scheduling Role in Advanced Manufacturing Systems: An Emerging Human Factors Domain
Authors: Sanderson Penelope M.
Published: July 2017

Advanced manufacturing technology is quickly displacing humans from the factory floor, but relatively little is known about how much responsibility humans should retain over plant operation. Scheduling operations are particularly critical to maintaining overall manufacturing system performance, and many researchers argue that humans should be retained in the control loop for this task. This paper critically reviews work done over the last 25 years on human scheduling abilities. The increasing amount of empirical work on human scheduling ability is widely dispersed, and many researchers are not aware of one another's work. Current work on manufacturing scheduling, field studies, and laboratory work on human scheduling abilities are reviewed. Methodological and conceptual problems are highlighted. The intention is to provide a sounder basis for future research on the human scheduling role by providing knowledge of what has been examined in the past and an awareness of the important issues for the future
Trunk Strength during Asymmetric Trunk Motion
Authors: Marras William S. , Mirka Garya
Published: July 2017

It is important to understand how trunk strength varies as a function of workplace factors so that the work environment can be designed to minimize the risk of low back injury. In this study maximal trunk torque production around the lumbosacral junction was measured in 44 subjects as trunk concentric and eccentric isokinetic velocity and trunk asymmetric line of action were varied. Trunk torque decreased by approximately 8.5% of maximum for every 15 deg of asymmetric trunk angle. Increases in concentric velocity decreased trunk strength, whereas increases in eccentric trunk velocity increased strength. Significant interactions were also found, and it was determined that the common finding that eccentric strength exceeds concentric strength is true only for forward trunk angles at all asymmetric angles. These results should have significant implications for the design of manual materials handling tasks.
Effects of Seat Slope and Hip Flexion on Spinal Angles in Sitting
Authors: Bridger Robert S. , Von Eisenhart-Rothe Carola , Henneberg Maciel
Published: July 2017

Lumbar and thoracic spinal angles of 25 male and 25 female subjects were measured in four sitting postures, with standing spinal angles used as reference. Subjects sat with either 90 deg or 65 deg of hip flexion on either flat or forward-sloping seats. Lumbar kyphosis was greatest when the flat seat/90-deg posture was adopted and least when the sloping seat/65-deg posture was adopted. The opposite was observed for the thoracic angles, and intermediate results were observed for the other two sitting postures. No statistically significant interactions were observed among seat slope, hip flexion, and subject sex. The findings are discussed with reference to the anatomy of sitting and factors influencing pelvic tilt and the implications for the ergonomic design of chairs.
Coding Effects on Performance in a Process Control Task with Uniparameter and Multiparameter Displays
Authors: Jubis Rebecca M. T.
Published: July 2017

Two experiments investigated the effectiveness of four methods for coding the operational states of targets in a process control task, under different levels of display density and inspection load, with search and identification tasks. In Experiment 1 subjects monitored one parameter (temperature) that could have four coded states. In Experiment 2 subjects monitored two parameters (temperature and oil level), each of which could have two coded states. Compared with partially redundant color coding or shape coding, color + shape coding and color coding led to quicker response time (RT) in a search task and mitigated the detrimental effects of increased display density. In addition, RT was faster with partially redundant color coding than with shape coding. Coding, however, had no effect on RT for the identification task. These findings held true across experiments. The effects of increased inspection load on RT were less pronounced with color + shape coding and color coding compared with the other coding conditions, but only when two parameters were monitored. Finally, RT was faster and responses were more accurate with one than with two parameters.
Thirty-Something Million: Should They Be Exceptions?
Authors: Vanderheiden Gregg C.
Published: July 2017

There are over 30 million people in the United States with disabilities or functional limitations (of which a major cause is aging), and this number is increasing. An examination of the role of human factors in addressing this population is presented which includes both special designs for disability/aging and the incorporation of disability/aging into mainstream human factors research and education. Statistics regarding the size and characteristics of this population are presented, including the costs of disability. Examples demonstrating the economic and commercial feasibility of incorporating disability/aging considerations in mass-market designs are provided along with a discussion of the benefits to nondisabled users.
Optimal Menu Hierarchy Design: Syntax and Semantics
Authors: Fisher Donald L. , Yungkurth Erika J. , Moss Stanley M.
Published: July 2017

Increasingly users must navigate through a hierarchy of menus in order to access the various functions available on a computer. As the number of functions proliferates and the menu hierarchies grow more complex, the time it takes users to access any given function has become unacceptably slow. Specifically, given a set of functions, recent studies have shown how to identify the structure of the complete, homogeneous hierarchy that minimizes the average time to access these functions. In this article a general method for finding the optimal hierarchy is developed. The method does not confine the search for an optimal hierarchy to the set of complete, homogeneous hierarchies; nor, given suitable input, does the method select as optimal a hierarchy that cannot be easily navigated. It is important to identify the optimal hierarchy because it can reduce the average access time considerably, in some cases (at least in theory) by almost 100%.
Alternative Displays for Discrete Movement Control
Authors: Flach John M. , Hagen Brent A. , O'Brien Daniel , Olson Wesley A.
Published: July 2017

This research examined performance in a single-axis discrete positioning task using three different mappings for the visual display of the movement space. In a normal display condition, displayed distance was proportional to actual distance. In a split-screen condition, 66.5% of the initial distance to the target was mapped into 50% of the visual space and 33.5% of the distance (containing the target) was mapping into the remaining 50% of visual space. Finally, in a log screen condition there was a logarithmic mapping from actual to visual space. The split-screen and log screen conditions resulted in magnification of the space containing the target and compression of space distance from the target. Results for movement time (MT) showed a significant effect of target width. MTs were longer for smaller targets. Performance with normal and log screens was equivalent in terms of overall level and in terms of rate of increase in MT with reduction in target size. A smaller rate of increase, however, was found for the split-screen display. MTs for the smallest target were faster with the split-screen display. Evidence suggests that fewer corrective movements were required for the smaller targets when using the split screen.
Eyestrain in VDU Users: Viewing Distance and the Resting Position of Ocular Muscles
Authors: Jaschinski-Kruza Wolfgang
Published: July 2017

Without fixation stimuli—for instance, in darkness—accommodation and convergence of the eyes reach an intermediate state that is relatively stable within a subject but which ranges from about 30 cm to infinity across subjects. This study investigated whether these oculomotor positions in darkness are related to visual strain. During work at a visual display unit (VDU), visual strain at a viewing distance of 50 cm was stronger than at 100 cm (with characters twice as large). The more distant the individual's dark convergence, the greater was the visual strain at the 50-cm viewing distance. When subjects were free to adjust the viewing distance to their comfort level, they chose distances between 51 and 99 cm (mean 74 cm) with characters 5 mm tall.
An Informational Perspective on skill Transfer in Human-Machine Systems
Authors: Lintern Gavan
Published: July 2017

Differentiation of perceptual invariants is proposed as a theoretical approach to explain skill transfer for control at the human-machine interface. I propose that sensitivity to perceptual invariants is enhanced during learning and that this sensitivity forms the basis for transfer of skill from one task to another. The hypothesis implies that detection and discrimination of critical features, patterns, and dimensions of difference are important for learning and for transfer. This account goes beyond other similarity conceptions of transfer. To the extent that those conceptions are specific, they cannot account for effects in which performance is better following training on tasks that are less rather than more similar to the criterion task. In essence, this is a theory about the central role of low-dimensional informational patterns for control of behavior within a high-dimensional environment, and about the adjustment of an actor's sensitivity to changes in those low-dimensional patterns.
Toward an Integration of Training Theory and Technique
Authors: Cannon-Bowers Janis A. , Tannenbaum Scott I. , Salas Eduardo , Converse Sharolyn A.
Published: July 2017

Reviewers of the training literature have generally concluded that training theory and practice are not well integrated, and that research findings are not often translated into useful training methods. In an effort to bridge the gap between training theory and practice, an organizing framework for conceptualizing training research is presented. The purpose of the framework is to highlight the linkages between training-related theory and technique in the areas of training analysis, design, and evaluation. The linkages are described in detail, and illustrated via consideration of research into mental models. We hope that the framework will lead to future research programs that enhance the transition of training research from theory into practice, and integrate more fully these two perspectives
An Ellipsoidal Representation of Human Hand Anthropometry
Authors: Buchholz Bryan , Armstrong Thomas J.
Published: July 2017

The goal of this study was to collect anthropometric data that describe the geometry of the surface of the hand and to model this anthropometry as a function of gross external hand measurements. The depth and breadth of each segment of the hand were measured at points that were spaced at approximately equal distances between the joints of the hand. Linear models using hand breadth as the independent variable explained from 12% to 47% of the variation in segment breadths and from 6% to 74% in segment depths. Ellipsoids are used in biomechanical models as an efficient mathematical description of the shape of kinematic segments for use in the determination of contact with other objects. Therefore the primary objectives of this study were to approximate the semiaxis dimensions for these hand segment contact bodies using a linear model of the gross anthropometry and to evaluate the accuracy with which ellipsoids describe the geometry of the hand segments. Graphical comparisons showed that differences between the ellipsoidal approximations and the breadth and depth measurements were largest near the joints. Data collected in this study could be used to create a set of overlapping ellipsoids that would provide a more accurate representation of hand geometry, and this representation could be adapted to biomechanical models that use ellipsoids to define segment geometry.
Age-Related Eye Disease, Visual Impairment, and Driving in the Elderly
Authors: Klein Ronald
Published: July 2017

As people age, a number of visual functions such as acuity, visual field, and night vision deteriorate. This decline in vision is associated in part with an increase in vehicular accidents per mile driven by the elderly. Four age-related ocular conditions-cataract, macular degeneration, open-angle glaucoma, and diabetic retinopathy-are primarily responsible for the decline in visual acuity and visual field in the elderly. Few epidemiologic data are available about these diseases, and at present they cannot be prevented. There is need for more information about visual decline and how it affects driving performance and for development of pragmatic approaches for detecting and assessing the elderly driver with functional visual deficits.
Dementia and the Older Driver
Authors: Kaszniak Alfred W. , Keyl Penelope M. , Albert Marilyn S.
Published: July 2017

The association between dementia and driving errors in older adults has been anecdotally noted by clinicians and caregivers. However, until recently, little empirical documentation of this association existed. This paper provides a critical review of available research on dementia and driving and discusses issues that must be considered in attempting to apply this developing body of research to practical problems, such as the relicensing process for selected drivers. This is followed by a discussion of recent research relevant to the development of potential procedures for screening patients with dementing illness-particularly Alzheimer's disease-for probable driving risk.
Strategic Behavior, Workload, and Performance in Task Scheduling
Authors: Moray Neville , Dessouky Mohamed I. , Kijowski Brian A. , Adapathya Ravi
Published: July 2017

Scheduling theory is proposed as a normative model for strategic behavior when operators are confronted by several tasks, all of which should be completed within a fixed time span, and when they are free to choose the order in which the tasks should be done. Three experiments are described to investigate the effect of knowing the correct scheduling rule on the efficiency of performance, subjective workload, and choice of strategy under different conditions of time pressure. The most potent effects are from time pressure. The reasons for the weak effect of knowing the rules are discussed, and implications for strategic behavior, displays, and decision aids are indicated.
The Effect of Picture Compression on Estimation of Depth
Authors: Henik Avishai , Tzelgov Joseph , Meisels Amnon , Dinstein Its'hak
Published: July 2017

The reduction of information in pictures is known as picture compression. The present work applies a psychophysical technique to evaluate the efficiency of compression algorithms. Two algorithms for stereo picture compression-one consistent with the suppression theory and the other with the fusion theory of depth perception-were compared and evaluated. Subjects estimated depth differences, and we found that these estimates under compressed conditions were as reliable as those under regular stereo conditions and significantly more reliable than estimates under mono conditions. We also found that picture compression results in a so-called depth recruitment phenomenon: the exponent of the psychophysical function was larger under compressed conditions than under the stereo condition. In contrast to performance in other tasks requiring depth perception, there was no difference in performance between the compression conditions.
A Computer-Aided Aptitude Test for Predicting Flight Performance of Trainees
Authors: Park Kyung S. , Lee Sang W.
Published: July 2017

Perceptual/psychomotor and cognitive tasks in a computer-aided aptitude test were studied to predict the success of a trainee in flight training. Pilots′ tasks were tentatively classified into five categories: tracking, reaction, memory, estimation, and visual scanning. To investigate the performance of a trainee in these categories, 16 single tasks and 10 dual tasks were examined. In the factor analyses three common factors (tracking, reaction, and memory) were meaningfully extracted. To select significant tasks for predicting flight performance, we performed stepwise regression and discriminate analyses. In the regression analyses, memory tasks were most significant in predicting the flight performance of a trainee. In the discriminate analyses, tracking tasks were most significant for distinguishing the passing and failing groups. The reaction tasks were of little significance in predicting the performance of flight trainees.
Coactivation of the Trunk Muscles during Asymmetric Loading of the Torso
Authors: Lavender Steven A. , Tsuang Yang-Hwei , Hafezi Ali , Anderson Gunnar B. J. , Chaffin Don B. , Hughes Richard E.
Published: July 2017

Materials handling tasks in industry are rarely performed in the midsagittal plane. Often these tasks, labeled nonsagittally symmetric or asymmetric lifting tasks, can be expected to lead to an unequal distribution of forces between the left and right sides of the body. Because of the large number of muscles capable of resisting loads in the torso, researchers are forced to make simplifications when using biomechanical models to estimate mechanical loading of the spine during such tasks. Simplifications and assumptions regarding the coactivation of antagonistic muscles are frequently used because sufficient experimental data do not exist. The present study was designed to quantify coactivation of the trunk musculature in response to applied asymmetric loads. This load was varied in direction from an anterior midsagittal plane orientation to a posterior midsagittal plane orientation in 15-deg increments. The results showed little coactivation when the applied load directions were anterior and within 45 deg of the midsagittal orientation. When load directions were greater than 45 deg, coactivation was quantifiable in ipsilateral and posterior muscle groups.