VTechWorks Repository :: Browsing by Author "Wierwille, Walter W."

Browsing by Author "Wierwille, Walter W."

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An accuracy analysis of techniques for measuring the durations of in-car manual tasks
Grant, Barry Steven (Virginia Tech, 1992-05-05)
Human factors research of automobile driver behavior often calls for timing in-car manual tasks. By measuring the time that a driver directs resources away from the primary task of driving, investigators can determine both if and where improvements need to be made in the driver-vehicle relationship. The present study was designed to compare the accuracy of various techniques for measuring in-car manual task durations. Additionally, this research was intended to reveal how closely these techniques approach the accuracy of the frame-by-frame video analysis method, which is time-consuming and expensive to perform. The study required three male and three female subjects to use an electronic stopwatch to measure "hand-off-wheel" times for 30 driver tasks. Each subject performed this procedure three times: once while sitting as an observer in the back seat of a research vehicle, once while watching a real-time video recording of task performance, and once while watching a one-sixth real-time video recording of task performance. Three independent variables were examined: timing Method (three levels), Duration of in-car task (three levels), and Subject (six levels). Dependent measures gathered were raw timing error (a measure of response bias), absolute timing error (a measure of response accuracy), and squared timing error (a measure of response consistency). Timing error was obtained by subtracting the measured time for a particular task from the "true" task time obtained by using the frame-by-frame video analysis technique. Analysis of the data indicated a significant effect of Method on response bias. Specifically, use of the slow-motion video technique resulted in overestimation of in-car task durations, and use of the two real-time techniques resulted in estimates of task durations that were either equal to or less than the true durations. Significant effects of Subject, Gender, and Subject x Method were also revealed. The results suggest that the on-road timing technique should be used in the future, since this procedure requires little in terms of cost and implementation time, and errors are small when compared with the frame-by-frame technique. Furthermore, it is recommended that only one experimenter serve as a timing analyst during an experiment to ensure a constant level of accuracy.
Advisory and alarm stimuli optimization for a drowsy driver detection system
Fahey, Sarah E. (Virginia Tech, 1995-07-05)
An experimental study was carried out to identify effective advisory and alarm stimuli to be used in a drowsy driver detection system. The envisioned system has three stages. In the first stage, previously developed detection algorithms would compute online drowsiness levels. If a driver's drowsiness level exceeds a predetermined threshold the system would proceed to stage two. At this point an initial advisory tone and a voice message would be played. If the driver does not respond, he or she would experience a realerting alarm. The third stage of the system would give the driver an option of using a drowsiness countermeasure to help maintain the re-alerted state. The goal of the present research was to determine the effectiveness of possible stimuli to be used in the second and third stages of the envisioned system. Eight initial advisory tones, two voice messages, eight alarm sounds, and five peripheral stimuli were investigated as part of stage two. In addition, six drowsiness countermeasures to be used in stage three were investigated. Eight graduate students in the Human Factors Engineering program at Virginia Tech volunteered as subjects. Subjects drove the automobile simulator throughout the experimental session. Data were collected using subjective opinion, paired comparisons, and effectiveness ratings. This study succeeded in answering many question regarding stimuli to be used in a drowsy driver detection, advising, and alerting system. The results of the study indicated very effective stimuli to be used in the advising and alerting stages of the envisioned system.
Algorithms refinement and threshold determination for a drowsy driver detection system
Fairbanks, Rollin J. III (Virginia Tech, 1995-12-05)
Research conducted over the past three years in the Vehicle Analysis and Simulation Laboratory at Virginia Tech has resulted in the development and validation of algorithms for the detection of driver drowsiness. Specifically, the goal of the research has been to develop the best possible drowsiness-detection algorithms using measures that can be computed while a vehicle is in motion with minimal interference with the driver. The results of these studies, which have been previously reported, generally support the feasibility of drowsy-driver detection and indicate that further analysis and refinement of the algorithms is warranted. This thesis researches several methods of refining existing driver-status algorithms, the integration of driver-performance deterioration measures, and the selection of appropriate alarm thresholds to be used in test and evaluation study. The results of five algorithm optimization refinements are described. Chapter 2 reports that the elimination of outlier dependent measure data prior to algorithm development was found not to improve algorithm accuracy. Chapter 3 describes that the addition of cross product and squared terms to the algorithms did not provide consistent improvement in algorithm accuracy. Chapter 4 reports that, although time-on-task variables were found to have some improved capability, they did not consistently add to the accuracy of the algorithms.
An Assessment of the Attention Demand Associated with the Processing of Information for In-Vehicle Information Systems (IVIS)
Gallagher, John Paul (Virginia Tech, 2001-04-25)
Technological interventions are being considered to alleviate congestion and to improve the quality of driving on our nation's highways. These new technology interventions will be capable of increasing the amount of information provided to the driver; therefore, steps must be taken to ensure they do not require a high attention demand. (Limited attention resources can be diverted from the primary task of driving to a secondary in-vehicle task). The attention demand required as part of the process of extracting information has been studied relatively extensively. However, the processing required to make complex decisions is not well understood and provides cause for concern. This study investigated the attention demand required to perform several types of tasks, such as selecting a route, selecting the cheapest route, and selecting the fastest route. The three objectives of this study were: 1) To investigate driver performance during IVIS tasks that required additional processing of information after the extraction of information from a visual display. 2) To develop a method for evaluating driver performance with regard to safety. This task was accomplished by performing an extensive review of the literature, and developing two composite measures. 3) To provide descriptive data on the proportion of drivers who exceeded a threshold of driver performance for each of the different IVIS tasks. An instrumented vehicle, equipped with cameras and sensors, was used to investigate on-road driver behavior on a four-lane divided road with good visibility. A confederate vehicle was driven in front of the instrumented vehicle to create a vehicle following situation. Thirty-six drivers participated in this study. Age, presentation format, information density, and type of task were the independent variables used in this study. Results from this study indicate that a high proportion of drivers' will have substantially degraded performance performing IVIS tasks such as selecting a route or a hotel from several possibilities. Findings also indicate that tasks involving computations, such as selecting the quickest or cheapest route, require a high attention demand and consequently should not be performed by a driver when the vehicle is in motion. In addition, text-based messages in paragraph format should not be presented to the driver while the vehicle is in motion. The graphic icon format should be utilized for route planning tasks.
Attentional demand evaluation for an automobile moving-map navigation system
Dingus, Thomas A. (Virginia Tech, 1987)
A study was undertaken to test and evaluate the human factors design aspects of an automobile moving-map navigation system. The primary objective of the study was to assess the driver attentional demand required by the navigation system during vehicle operation. A secondary objective of the study was to assess design specifics and determine whether or not the design was optimal in terms of efficiency of use in an automotive environment. Thirty-two driver-subjects drove a specially instrumented 1985 Cadillac Sedan de Ville on public roadways for this research. A cross-section of driver-subjects (both genders, ages 18 to 73, and driving experience from 2,000 to 40,000 miles per year) participated, and a cross·section of roadway types (residential, two-lane state route, and limited·access four-lane) and traffic conditions (light and moderate) were used as part of this research. The driver-subjects were asked to perform a variety of tasks while operating the research vehicle. These tasks included navigation tasks normally performed while using the navigation system, as well as a wide variety of conventional automotive tasks (e.g., tuning the radio or reading the speedometer) normally performed during vehicle operation. The purpose of asking the driver-subjects to perform a variety of conventional automotive tasks was so that direct comparisons in attentional demand could be made between tasks performed daily in an automotive environment and the navigation tasks. Twenty-one performance and behavioral measures were collected and analyzed for this research. These measures included eye—scanning and dwell-time measures, task-completion-time measures, and a variety of measures indicating driver performance and behavior. The data analyses for these measures focused on two major goals. First, the analyses determined which tasks (both navigator and conventional) required the highest attentional demand. Second, the analyses were used to determine groups of tasks which, for all practical purposes, required equivalent attentional demand. The results of the analyses indicated that the navigation system is a relatively effective device, useful for its intended purpose. The results also indicated that a number of design improvements are required, however, to optimize the safety and efficiency of the device. An iterative process of design improvement and further research into the effects of improved design on required attentional demand is therefore recommended.
Auditory localization of in-vehicle crash avoidance warnings as a cue to hazard direction
Tan, Adrian K. (Virginia Tech, 1996)
A human factors experiment was conducted to determine the effects of warning sound type, speaker location, and age on the ability to localize the direction of warning sounds in a passenger vehicle. The purpose of these warning sounds is to alert a driver of potential roadway hazards detected by an in-vehicle crash avoidance warning device. Auditory localization of the warning sound was investigated as a means of indicating hazard locations relative to the vehicle. Four dependent variables were measured— response time, decision time, accuracy, and azimuth—to assess the speed and accuracy of localizing six different warning sounds from each of sixteen speaker locations. The six warnings were found to be appropriate for crash avoidance warning applications through a previous study. The localization task was performed in the passenger compartment of a stationary 1995 Ford Taurus sedan. Subjects input their responses through a joystick. The results of the study suggest that the implementation of localized auditory crash avoidance warnings could be beneficial in the timely identification of hazard locations in the vehicle environment. People can quickly localize the general direction of warning sounds (= 1 s to 1.5 s); however, localization effectiveness depends on the proper choice of warning sound and speaker location. Otherwise, potentially serious problems can occur if poor choices are made. The study was successful in identifying sounds and speaker locations that performed best and provides recommendations for speaker placement for each of six potential hazard directions for the vehicle tested.
Automobile navigation methods: effectiveness, efficiency, and strategy
Antin, Jonathan F. (Virginia Polytechnic Institute and State University, 1987)
A study was performed to evaluate the effectiveness, efficiency, and strategy associated with three navigation methods: memorized route, conventional paper map, and a moving-map navigational display (the navigator). Thirty-two driver-subjects of both genders, and wide ranges of age (18-73) and driving experience (2,000 to 40,000 miles per year) navigated along public roadways for this research using a specially instrumented automobile. A variety of different roadway conditions were also used for this research including limited access four-lane highways, two-lane state routes, and city streets. In addition, the research was conducted under conditions of both light and moderate traffic densities. Measures taken include eye movement, navigation effectiveness, and driving performance measures. Results showed that the paper map took longer to study at the beginning of a run than the navigator. Even with this handicap, the total time taken when using the paper map was not significantly different from the time taken to use the navigator. Also, there were no differences in the directness or quality of routes selected when using either the paper map or the navigator to navigate. These findings were a result of the strategies adopted in the use of the various methods of navigation. During the initial study phase the paper map was essentially used to plan the entire route from start to finish. After the initial phase, the map was used only as an occasional reference. In contrast, effective use of the navigator could only be accomplished by repetitively glancing at the display to acquire important information as it was updated and presented. As a result, subjects spent more driving time glancing to the navigator than the paper map, and it substantially drew the subjects' gaze away from the driving task relative to the norm established in the memorized route condition, as well as in comparison to the paper map. Still, driving performance did not greatly change as a function of navigation method indicating that the additional visual attentional demand associated with the navigator was drawn primarily from spare driver resources. It is also very likely that the novelty of the navigator was responsible for some portion of the glance time spent on it.
A behavioral evaluation of command-selection aids for inexperienced computer users/
Elkerton, Jay (Virginia Polytechnic Institute and State University, 1985)
Two experiments were conducted to determine the feasibility of providing online command-selection aids to novice users of an information retrieval system. The results of the first experiment revealed a difference in the mean and variability of search performance between novice and expert computer users. Half of the novices were performing much like experts, while the rest of the sample was extremely slow. These slower novices were using inefficient scrolling strategies and appeared to be unfamiliar with the structure of the database. The second experiment evaluated whether novices could be assisted or trained with command-selection aids developed from the behavior of experts. The command-selection aids were defined in a 3 X 3 mixed factor design with type of model (frequency, sequence, or plan-based) as the between-subjects variable and dialogue initiative (user, computer, or mixed) as the within-subjects variable. The frequency and sequence models presented and ranked search procedures based on a command-usage profile and a command-transition matrix, respectively. The plan-based model presented an ordered set of search procedures with verbal explanations. All models were constructed for groups of homogeneous search problems selected by a sorting and cluster analysis. The three dialogue-initiatives determined whether the user, the computer, or both the user and computer controlled presentation of advice. Administration of the dialogue initiatives was completely counterbalanced and was followed by a final unaided transfer session. As a result of receiving online aiding, the wide ranging search performance of novice subjects was improved both during assistance and transfer. Performance of aided novices was superior to the slow novices and equal to the fast novices and experts. All three command-selection models were equally effective, with exception of the sequence model which sometimes presented frequent and complicated advice. Of the dialogues, mixed-initiated advice was ineffective during the first aiding session possibly due to the difficulties novices faced deciding whether to receive the suggested assistance. The conclusion of the study was that online command—selection aids can be effective if providing appropriate feedback and minimizing the amount of dialogue in aiding.
Charting Presence in Virtual Environments and its Effects on Performance
Snow, Michael P. (Virginia Tech, 1998-08-21)
Virtual reality (VR) involves an attempt to create an illusion that the user of the VR system is actually present in a synthetic (usually computer-generated) environment. Little is known about how various system parameters affect the illusion of presence in a virtual environment (VE). In particular, there seem to be very little quantitative data on which to base VR system design decisions. Also, while presence (or immersion) in VEs is a primary goal of VR, not much is known about how this variable affects task performance. The goal of this research was to provide a ratio-scale measure of perceived presence in a VE, to explore the effects of a number of environmental parameters on this measure and construct empirical models of these effects, and to relate perceived presence to user performance. This was done by manipulating eleven independent variables in a series of three experiments. The independent variables manipulated were scene update rate, visual display resolution, field of view, sound, textures, head-tracking, stereopsis, virtual personal risk, number of possible interactions, presence of a second user, and environmental detail. Participants performed a set of five tasks in the VE and rated perceived presence at the end of each set using the technique of free-modulus magnitude estimation. The amount of time spent in the VE was also recorded. The results indicate that the VR system parameters manipulated and analyzed in this research did affect participants' subjective feeling of presence in the VE. Field of view, sound, and head-tracking showed the largest effects. Other significant effects found were those of visual display resolution, texture-mapping, stereopsis, and the presence of a second user. Free-modulus magnitude estimation worked well as a measure of perceived presence. A positive relationship was found between perceived presence and task performance, but this relationship was relatively weak. Second-order empirical models were constructed that predicted perceived presence with moderate success and, with less success, task performance.
A comparison between predictive and formative cost-effectiveness evaluation techniques for the assessment of lecture and computer-based multimedia training
Neale, Vicki L. (Virginia Tech, 1996)
In an effort to validate a predictive (as opposed to a traditional formative or summative) cost-effectiveness model, a study was conducted to evaluate Kearsley and Compton's (1981) Benefits Model. Costs were input into the model as they applied to the design, development, and dissemination of two training programs on the topic of teaching individuals how to detect the level of drowsiness of their colleagues during team operations. The benefits of the training programs were identified, classified, and quantified as they applied to two media: lecture and computer-based multimedia. The experimenter identified the training system parameters, training benefits, and operational benefits. Then, for the predictive approach, the relationships between training system parameters, training benefits, and operational benefits were classified based on expert opinion. Quantification concerned the assignment of values (-1 or +1) based on expert opinion. The costs to design, develop, and disseminate the training programs were determined based on the parameters of the project. Finally, based on all information present, experts determined which of two training programs would be the most cost-effective to disseminate. To determine the accuracy of the Benefits Model as a predictive assessment tool, the same identified training system parameters, training benefits, and operational benefits were evaluated from a traditional formative evaluation approach. An empirical evaluation was conducted for the two training programs and a determination of the most cost-effective training medium was made. The data collected in the traditional formative evaluation approach was then compared to the experts' ratings and choice of training programs. For both the predictive and formative evaluation approach to determining cost-effectiveness, the computer-based multimedia was chosen as the most cost-effective training medium. However, for the predictive approach, the experts’ choice was based either solely or heavily on dollar amounts associated with design, development, and dissemination, while the data obtained through the validation process were given little or no weight. All experts stated that it would not have been possible to use the information gathered through application of the Benefits Model to determine cost-effectiveness with any confidence.
A comparison of three subsidiary tasks used as driver drowsiness countermeasures
Hardee, Helen Lenora (Virginia Polytechnic Institute and State University, 1985)
Two previous studies performed at Virginia Tech have shown that it is feasible to detect drowsy drivers using driving performance and physiological measures. Therefore, assuming that drowsiness can be detected, it becomes important to develop methods (countermeasures) by which drivers can regain and maintain alertness. The current study was thus undertaken in an attempt to evaluate three subsidiary tasks which differed only in regard to input modality (auditory, tactual, or visual) in terms of: 1) the degree to which they aided the driver by maintaining or restoring alertness; and 2) the degree to which the responses to these tasks could be used to detect drowsiness. Subjective measures of drowsiness were also obtained to provide an additional source of verification of level of drowsiness. To accomplish these objectives, a total of 12 male and female driver-subjects drove a moving-base simulator continuously from 12:30 a.m. to 3:00 a.m. During this time, the subjects performed each of the subsidiary tasks for a 30-minute period; they also drove for a 30-minute period during which no subsidiary task was performed. During the simulated, nighttime, highway driving scenario, 20 driving performance, behavioral, and physiological measures were collected for each 3-minute driving interval, along with 5 subsidiary task measures and subjective alertness ratings. The experimental results indicated that none of the three subsidiary tasks provided an effective means of maintaining driver alertness. However, the results of a second series of discriminant analyses did indicate that driver impairment due to drowsiness could be reliably detected with linear combinations of subsidiary task and driving measures. In fact, promising discriminant models for the auditory and visual tasks were identified which employed a subsidiary task response measure of the number of correct responses to the subsidiary task during each 6-minute driving interval as well as a physiological measure of the subject's heart rate variance; these models showed overall classification error percentages as low as 3% and 8%. Finally, the analyses of the subjective alertness ratings indicated that subjects' ratings were not significantly affected by either the type of subsidiary task performed or time-on-task.
The development and validation of algorithms for the detection of driver drowsiness
Wreggit, Steven S. (Virginia Tech, 1994)
This study was undertaken to determine which variables and combination of variables could be used for the prediction of on-the-road drowsiness. Numerous driver-vehicle performance measures and secondary task performance measures were collected so that the predictability of several definitional measures of drowsiness could be tested. Twelve volunteer subjects were employed in the algorithm development phase of this study. All subjects were from the driver population in the Blacksburg, Virginia area. The participants were sleep deprived and drove a moving base simulator late at night in order to increase the likelihood that they would experience drowsiness while driving. After completion of data collection, numerous algorithms were developed using multiple regression and discriminant analysis methods. Another twelve volunteer subjects were subsequently employed in the algorithm validation phase of this study. Similar physiological and driving performance measures were collected during both phases of the study. All subjects were from the same driver population. All subjects were run under similar conditions as those in the algorithm development phase. Algorithms that appeared promising which were developed in the first phase of study were validated by applying them to the new data in an attempt to predict drowsiness on a new subject pool. It was found that drowsiness could be detected on a new subject pool and that the rate of correct predictions was quite high. There was no general decrease in predictive power of the drowsiness detection algorithms when applied to new data. Results showed that an accuracy rate of over 90 percent could be accomplished when output from the detection algorithms were classified into categories of "Awake," "Questionable," and "Drowsy."
Development of a Performance Specification for Camera/Video Imaging Systems on Heavy Vehicles
Wierwille, Walter W.; Schaudt, William A.; Spaulding, Jeremy M.; Gupta, Santosh K.; Fitch, Gregory M.; Wiegand, Douglas M.; Hanowski, Richard J. (United States. National Highway Traffic Safety Administration, 2008-07)
This document provides revised final performance specifications for Camera/Video Imaging Systems (C/VISs) used in heavy vehicles. The specifications are based on a combination of analyses including driver needs and human factors, current and future video technology, systems analyses, focus groups, preliminary tests, and formal on-road tests. In these specifications C/VISs are divided into two categories: surrogates, which take the place of the essential side mirrors, and enhancements, which are all other applications. The specifications are written in three parts: an introductory section defining terms and stating general requirements, a section providing detailed specifications for two surrogate configuration concepts and nine enhancement concepts, and a section providing additional common detailed specifications. The specifications are intended to serve as a culmination of best approaches and practices for development of viable C/VISs. It is expected that if the specifications are followed, they will result in feasible and reasonably uniform implementation, thereby making the heavy vehicle driver's task more efficient. For background information and research justification of the specifications, the reader is referred to the companion final report, Development of a Performance Specification for Camera/Video Imaging Systems on Heavy Vehicles, DOT HS 810 960 (Wierwille, Schaudt, Spaulding, Gupta, Fitch, Wiegand, & Hanowski, 2007).
Development of an evaluation program for automotive instrument panel design
Kurokawa, Ko (Virginia Tech, 1990-10-31)
This dissertation research was a part of a multi-year research effort, objectives of which were (I) to characterize attentional demands of drivers performing automoltive instrument panel (IP) tasks, (2) to develop a methodology to quantify the driver attentional demands, (3) to examine a variety of factors which influence the visual attentional demand (VAD) and concurrent manual demand (CMD) through a comprehensive review of previous studies and a series of experiments, and (4) to develop a computer program to evaluate contemporary and future automotive IP designs on the basis of their attentional demands. In the first part of this dissertation, an extensive literature review of methodologies and findings concerning automotive IP task performance is presented. Most of the earlier studies reported task completion times (also referred to as response times and transaction times), which did not provide a precise detail of the operation of an instrument. More recent studies, on the other hand, recorded the driver's eye movements while performing an IP task, and measures of VAD were analyzed. Among the variety of methodologies to measure eye movements, the limbus and pupil tracking technique using a commercially available video cassette recorder (VCR) represents an ideal compromise among precision, cost, and size/weight. Combined with the traditional response time measure, the number and average length of glances, which are determined by a frame-by-frame analysis of the eye movement recording tape, allow a quantitative evaluation of driver IP task performance. A series of three experiments conducted in the moving-base driving simulator in the Vehicle Analysis and Simulation Laboratory forms the second part of this dissertation. The objectives of these experiments were (1) to validate the use of the driving simulator for collecting driver performance data on IP tasks, (2) to examine factors which influence the simulated driving workload, e.g., introduction of random crosswind and road curvature, (3) to expand the existing database on conventional IP tasks, (4) to examine the effects of IP macro- and micro-clutter on driver task performance, and (5) to investigate the issues related to control labelling, i.e., random versus sequential labelling and label abbreviation. Some of the important findings from the simulator experiments were (1) the driver IP task performance data collected under the zero crosswind and straight road conditions were found to be acceptably close to those in the in-car, on-road study during the first phase of this research program (Hayes, Kurokawa, and Wierwille, 1988), (2) IP macroclutter, represented by the number of instruments in the IP, was linearly related to the complexity of an IP task, reflected in the number of glances to IP, (3) IP microclutter, represented by the number of controls within an instrument, was linearly related to both complexity (number of glances to IP) and difficulty (average length of glances to IP) of an IP task, and (4) concise and distinct labels were more desirable as they required fewer glances and were located more quickly than their fully spelled counterparts. In the third part of this dissertation, a computer program (IPanalyzer) which was developed to aid automotive IP designers in evaluation of an IP design is discussed. Users of IPanalyzer can obtain driver IP task performance estimates (1) empirically from the existing experimental data, (2) by assessing the difficulty, complexity, and manual demand of a given task, or (3) by decomposing a task of interest into elements and categorizing them by their behavioral characteristics. Instructions for using IPanalyzer are supplemented by detailed descriptions and discussions of the data on which the driver IP task performance estimates are based. Finally, limitations of the current evaluation program are discussed, and a direction for future research and development are suggested.
Effects of In-Vehicle Information Systems (IVIS) Tasks on the Information Processing Demands of a Commercial Vehicle Operations (CVO) Driver
Blanco, Myra (Virginia Tech, 1999-12-10)
This study was performed with two main goals in mind. The first goal was to understand and predict "red-lines" and "yellow-lines" in terms of what the CVO driver can process without hindering the primary task of driving. The second goal was to collect conventional secondary task data for CVO driving performance. An on-the-road experiment was performed with the help of 12 truck drivers. Type of task, presentation format, information density, and age were the independent variables used in the experiment. The 22 dependent measures collected were grouped into the following categories: eye glance measures, longitudinal driving performance, lateral driving performance, secondary task performance, and subjective assessment. The findings of this study strongly suggest that paragraphs should not be used under any circumstance to present information to the driver while the vehicle is in motion. On the other hand, the Graphics with Icons represent the most appropriate format in which driving instructions and information should be presented for IVIS/CVO tasks. In order to avoid a high visual attention demand to the driver due to a secondary task, only simple search tasks with the most important information shall be presented. Although the suggested format, type of task, and information density represent a higher visual attention demand than a conventional secondary task, these characteristics seem to bind a task with a moderate attentional demand. Other combinations of format, type of task, and information density will cause an increase in the driver's attentional demand that will consequently deteriorate their driving performance causing unsafe driving situations.
Effects of instrument panel luminance and hue on simulator driving performance and driver preferences
Imbeau, Daniel (Virginia Polytechnic Institute and State University, 1987)
Twenty-four subjects, each having a valid Virginia driver's license (males and females of ages from 20 to 73), read aloud words presented on two displays while driving a simulated vehicle in night-time conditions. The words, emulating printed legends found on automobile instrument panels, were presented in different hues (eight levels), brightnesses (two levels), character sizes (four levels), and word complexities (two levels). The brightness levels had been subjectively determined in a preliminary experiment by subjects representative of the older and younger segments of the driver population. Each of two groups of drivers determined one brightness level that was subjectively equal among the eight hues. For each word presented, six reading and driving performance measures were taken. Also, subjective attractiveness, subjective comfort, and subjective ease of readability of each hue by brightness treatment combination, were measured. Globally, the results tend to indicate that color of illumination per se had a reliable effect on subjective preferences but a negligible effect on reading and driving performance. Brightness had an impact on performance only with the smaller character sizes. For the larger sizes, brightness level as selected by the subjects (in the preliminary experiment) had a negligible effect on performance. Character size had marked effects on both performance and subjective preferences. The two smaller character sizes tested yielded significant performance decrements for older drivers while the two larger sizes yielded best performance and were better accepted by all subjects. Word complexity did show a significant effect on glance time at the displays with all character sizes. The results of the experiment were transformed into a set of guidelines for use in design of automobile instrument panels. A number of recommendations for future research are also included.
The Effects of Multitasking on Quality Inspection in Advanced Manufacturing Systems
Pesante-Santana, José A. (Virginia Tech, 1997-11-07)
Technological and strategic developments have changed the role of human operators in the manufacturing environment. The highly specialized work force of the low-tech manufacturing system has evolved into the multi-functional work force of the high-tech manufacturing system. Among the multiple tasks that an operator is expected to conduct in advanced manufacturing systems (AMS) are job scheduling, inventory planning, machine set-up, problem solving, and quality inspection. The quality inspection task in AMS consists of a search component, frequently conducted by a machine, and a decision making component conducted by the operator. This quality inspection system is often referred to as a hybrid inspection system (HIS). It has been demonstrated that in general the performance of HIS is better than that of pure human or pure automated inspection systems. This research investigated the effects of different types of defects (presented at the same time in the inspected parts), multitasking (concurrently conducting independent tasks), and their interaction on the operator's performance in the quality inspection task (with a memorized quality criteria) in an AMS. The results indicate that the performance of the operator in the quality inspection task while multitasking in an AMS will be determined not only by the variety of defects that can be present in the inspected parts, but also by the mental processing resources required to meet the demand imposed by the multiple independent tasks and the memorized quality criteria. The best performance will be obtained when the additional tasks' load minimizes the monotony of the quality inspection task without interfering with the processing resources needed for the memorized quality criteria.
The effects of raster structure suppression on visual thresholds, target acquisition performance, and image quality
Beamon, William S. (Virginia Tech, 1979-06-15)
A television image is formed by a series of parallel luminous lines called a raster. The visual prominence of the raster structure interferes with the extraction of information from the image. The raster may be suppressed experimentally by a deflection process called spot wobble. Experiments were conducted to determine the effects of raster structure suppression on visual sine wave modulation thresholds and dynamic target acquisition performance using normal and noise degraded imagery. Results indicate raster structure suppression and improvements in Sine wave threshold sensitivity are correlated and that a suppressed raster significantly improves target acquisition performance for noise-free conditions. Performance correlations with the modulation transfer function area (MTFA) image quality metric were not as good as were the correlations between observer task performance measures and areas under the threshold functions. A rationale for improving the efficacy of the MTFA image quality metric was postulated.
Effects of visual display and motion system delays on operator performance and uneasiness in a driving simulator
Frank, Lawrence H. (Virginia Polytechnic Institute and State University, 1986)
Empirical Methods for Evaluating Video-Mediated Collaborative Work
Kies, Jonathan K. (Virginia Tech, 1997-03-18)
Advancements in computer technology are making video conferencing a viable communication medium for desktop computers. These same advancements are changing the structure and means by which information workers conduct business. From a human factors perspective, however, the study of new communication technologies and their relationships with end users presents a challenging research domain. This study employed two diverse research approaches to the problem of reduced video frame rate in desktop video conferencing. In the first study, a psychophysical method was used to evaluate video image quality as a function of frame rate for a series of different scenes. Scenes varied in terms of level of detail, velocity of panning, and content. Results indicate that for most scenes, differences in frame rate become less detectable above approximately 10 frames per second (fps), suggesting a curvilinear relationship between image quality and frame rate. For a traditional conferencing scene, however, a linear increase in frame rate produced a linear improvement in perceived image quality. High detail scenes were perceived to be of lower quality than the low detail scenes, while panning velocity had no effect. In the second study, a collection of research methods known as ethnography was used to examine long-term use of desktop video by collaborators in a real work situation. Participants from a graduate course met each week for seven weeks and worked on a class project under one of four communication conditions: face-to-face, 1 fps, 10 fps, and 25 fps. Dependent measures included interviews, questionnaires, interaction analysis measures, and ethnomethodology. Recommendations are made regarding the utility and expense of each method with respect to uncovering human factors issues in video-mediated collaboration. It is believed that this research has filled a significant gap in the human factors literature of advanced telecommunications and research methodology.

Browsing by Author "Wierwille, Walter W."

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