bluuebunny/crossref_metadata_2025 huggingface dataset:
Judged Distance to Virtual Objects in the near Visual Field
Authors: Ellis Stephen R. , Menges Brian M.
Published: January 2012

Errors in judged depth of nearby virtual objects presented via see-through, helmet mounted displays are examined as a function of monocular, biocular and stereoscopic viewing conditions, accommodative demand and subjects’ age. These errors are argued to be related to changes in binocular vergence. Suggestions for improved control of the judged distance to virtual objects and the cause of the judgment errors are briefly discussed.
Interference and Information Organization in Dynamic Memory
Authors: Venturino Michael , Miller Sheryl L. , Ercolano Karenza A. , Josephson Keith
Published: January 2012

Two experiments were performed in order to explore the relationship between two memory phenomena that determine one's ability to keep track of continually changing information: attribute similarity and information organization. In Experiment 1, attribute similarity was minimized while information organization was varied. Results showed that the memory requirements involved in maintaining numerous object-attribute associations (i.e., grouping) did not hinder subjects’ ability to successfully retrieve information, but did affect temporal aspects of the retrieval process itself. In Experiment 2, information organization was varied under conditions of greater attribute similarity. In the presence of substantial information similarity, information organization had a beneficial effect, allowing for greater recall accuracy when the information could be meaningfully grouped, while also not incurring a temporal cost. The type of retrieval errors were also classified and discussed.
Personal Minimums for Aviator Risk Management
Authors: Jensen Richard S. , Guilkey James , Hunter David R.
Published: January 2012

This paper discusses the results of the development of a personal minimums pilot training program to help general aviation pilots manage risks in their decisions about takeoff. Result of an initial field testing exercise in various locations around the USA are also presented. The key safety point to the training is the commitment of pilots to their self-developed minimums for flight which are expected to be more conservative than those established by the FAA. The field tests revealed high acceptance of the concept and the engaged learning method used in the presentation.
Automation and Crew Performance: The Importance of Who and What
Authors: Jentsch Florian , Bowers Clint
Published: January 2012

In the past, “automation” in the cockpit has been associated with both an increase and a reduction in workload, performance, and crew communications. A reason for these apparently contradictory results could be that different types of automation were studied, for example, automation that required little vs. considerable interaction with a machine. The current study investigated whether automation of different task domains for different crewmembers has differential effects. Sixteen pilots formed two-pilot crews. The crews each completed four experimental flights in a PC-based simulator, encountering different levels of automation. Systematically, an automated system for the pilot (a simple autopilot) and one for the copilot (a navigation computer) were made available or were unavailable, alone or in combination. The results showed that the automation manipulations improved task performance only when they were combined. Additionally, the use of the navigation computer reduced communications within the cockpit, while the autopilot was associated with larger contributions by the pilot. Further, mental workload and frustration were lower when the navigation computer was available. Also, perceived effort was lower with the autopilot on. The results of the current study suggest a more detailed picture of automation effects than previously known. Additionally, the results suggest that different types of automation can interact to create unexpected effects that may not be uncovered if one studies automated systems individually.
Cognitive Aging: General versus Process-Specific Slowing in a Visual Search Task
Authors: Gorman Michael F. , Fisher Donald L.
Published: January 2012

The fact that response times increase as one ages has long been established. Previously, a model of general slowing in the nonlexical domains has done a really good job of explaining the differences between older and younger adults. However, an alternative process-specific model has not been conclusively ruled out. This experiment tested general and process-specific models of slowing in the nonlexical domain using older and younger adults performing a visual search task. The task manipulated the presence of the target, the number of search items, and the structure of the display of the search items. It was found that a process-specific model explained significantly more of the variability than a general model of slowing. It was also discovered that the process most greatly affected was that of deciding to terminate a search when no target was present in the display.
Paired Associate Learning: Age Differences
Authors: Katsikopoulos Konstantinos V. , Fisher Donald L. , Pullen Michael T.
Published: January 2012

The issue of age related differences in performance during the acqusition phase of a paired associate learning task is discussed within the framework of a precise mathematical tool. A two-stage, four-state Markov model is employed to analyze the data sets from two age groups consisting of 24 subjects each. The relative efficiencies of the acqusition processes of the younger and the older groups of adults are reflected in the different values of parameters. (These values were obtained by optimizing the fit of the model to the two data sets). The two major findings are: (i) the younger adults form associations (even temporary ones more easily) and (ii) these associations tend to decay less quickly, again in the younger adults. The results speak against the general decrement hypothesis, allthough further investigation is needed.
The Ordering of Over-the-Counter Pharmaceutical Label Components
Authors: Vigilante William J. , Wogalter Michael S.
Published: January 2012

Recently there has been increasing interest in enabling consumers to more easily acquire information from over-the-counter (OTC) nonprescription pharmaceutical labels. Standardization of the format of labels is being considered by industry, government, and health-related professional organizations as a way to facilitate their usability. Potentially standardization could assist consumers in quickly locating information that they need to use the medication safely. The purpose of the present research is to determine whether consumers have a consistent preference for the ordering of information (component headings) on OTC drug labels. If so then this could serve as a partial basis for standardization. Results showed relatively consistent orders across four drugs and three participant groups (adults attending a flea market, senior citizens, and undergraduates). In general, the data indicate that people prefer that labels first provide what the drug is used for (indications); second provide information on associated hazards (warnings, cautions, drug interaction precautions) and use (directions); and third provide information on active ingredients. The remaining components were preferred in the following order: whether the package is safety sealed, inactive ingredients, storage instructions, manufacturer information, and then finally the bar code. Given the reasonable consistent orders generated by participants it seems plausible that if standardization were implemented that the ordering would roughly reflect this basic ordering.
Cognitive Task Analysis of Air Traffic Control Instruction to Identify Rule-Based Measures of Student Simulator Performance
Authors: Redding Richard E. , Seamster Thomas L.
Published: January 2012

This study is the first cognitive task analysis of the air traffic controller student evaluation process. The goal was to identify cognitive and behavioral rule-based measures for assessing student simulator performance. A knowledge structure analysis of experienced instructor's sorting of assessment concepts was followed by a protocol analysis of instructor's simulator training sessions with students. The data were translated into IF-THEN cognitive and/or behavioral assessment rules for use in an automated evaluation or intelligent tutoring system. Traditional summary measures of performance activate the rules, providing real-time diagnosis of student performance. This event-driven approach determines not only that some action is incorrect but also what is missing from the student's knowledge or skill base.
Corporate Memory: Lessons Learned from Innovative Human Factors Researchers
Authors: Hutton Robert J. B. , Klein Gary
Published: January 2012

Lessons learned from experienced researchers can provide an invaluable resource for any organization. The purpose of this project was to interview successful researchers from the Armstrong Laboratory (AL/HEA) at Wright-Patterson AFB to learn from some of their successful projects. The ultimate goals of the project were threefold: to provide AL/HEA with an alternative way to capture and describe the successes of their researchers; to identify themes that emerged from these projects regarding researchers' problem-solving, project leadership, and project management skills; and finally, to provide recommendations to the organization which would promote and support ways to increase opportunities for successful projects.

Eleven interviews were conducted. Each of the researchers was interviewed about a project that had provided some concrete benefit to the Air Force. We used a form of the Critical Decision method to elicit 15 accounts. Several themes were identified that characterized the research projects, and recommendations were made to encourage the initiative of laboratory personnel and increase opportunities for successes.
A New Mechanism for Attention Direction in Information Management
Authors: Coury Bruce G. , Semmel Ralph D.
Published: January 2012

Information systems can present an enormous amount of information to a user. One of the important issues in the design of the user interface is directing the user's attention to the critical information in a situation, especially when a user's request for information produces an uncertain result. The purpose of this paper is to describe how a unique approach provides a solution to the problem of attention direction while simultaneously representing the database designer's intent to the user to facilitate user/system communication.
Sharpness of Lid Edges
Authors: Konz Stephan , Aye Don , Fu Yanci
Published: January 2012

In Experiment 1, 15 plexiglass lids were constructed, using all combinations of 3 diameters (32, 70, 82.5 mm) and 5 edges (having a radius of curvature of 0, .8, 1.6, 2.4 and 3.2 mm). The lids were inserted into a torquemeter and held vs 2.3 kg-m of torque. The 44 adult subjects (18 M; 26 F) indicated their discomfort. Gender significantly affected discomfort, with female discomfort values about 70% greater than male values. For the same radius of curvature, discomfort was highest at 32 mm dia, intermediate at 82.5 mm and least at 70 mm.

In Experiment 2, 82.5 mm dia lids with edges of .8, 1.6 and 2.4 mm radii were used by 10 subjects (5 M, 5 F). The torques were 1.1, 1.7, 2.3, 2.8 and 3.4 kg-m. Female discomfort vote increased 1.9/ kg-m while male vote increased 1.2/kg-m.
Development of a temperature control procedure for a room air-conditioner using the concept of just noticeable difference (JND) on thermal sensation
Authors: Cho Chang K. , Lee Hak Min , Yun Myung Hwan , Lee Myun W.
Published: January 2012

Temperature control for an air-conditioner is an ergonomic design variable. Ergonomic studies on the thermal sensations in room environment are relatively few while many studies are available for the thermal sensations in extremely warm/cold conditions. The objective of this study was to find out factors which affect the cutaneous thermal sensations and so to propose new cooling control procedure using the JND(just noticeable difference) values of cutaneous thermal sensation for the design of an air-conditioner. The JNDs of cutaneous thermal sensation corresponding to the skin, room temperatures and temperature change rates were obtained. Based on the result of the study, a new cooling procedure using the concept of JND on thermal sensation was developed and applied to a new air-conditioner model.
Effect of Comfort on Mood States Affecting Performance
Authors: Paul Rajendra , Morrow Jane , Helander Martin
Published: January 2012

This study investigated the hypothesis that excessive physical comfort adversely affects mood states generally associated with superior mental performance. This hypothesis was explored in an experiment on office chairs. Eleven subjects evaluated three chair designs varying in comfort for eight hours on three separate days. The subjects performed a word processing task from 8 a.m. to 5 p.m. Comfort and discomfort were evaluated using the Shackel Scale and the Corlett Scale. Mood states were evaluated using a mood profile survey. The results suggested that the most comfortable chair induced mental mood states such as boredom, tiredness, sluggishness, (lack of) alertness and (less) energetic feeling which are generally associated with lower mental performance. It is suggested that for knowledge workers, comfort and performance may follow an inverted-U relationship. Too little or too much comfort may be detrimental to both physical and mental performance. This moderation on the view of comfort has considerable implications for the design of the modern workplace, particularly for office furniture. Its relevance to the sedentary work-styles prevalent in the United States is also discussed.
If I Knew Then what I Know Now: The Continuing Saga of a Corporate Ergonomist
Authors: Larson Nancy LJ
Published: January 2012

Convincing Corporate America to allocate funds and resources to an ergonomics program often requires the corporate ergonomist to assume roles of magician, juggler and Madison Avenue marketer. Even though corporations come in a variety of sizes and structures, their ergonomics programs have common concerns, problems and goals. The collective expertise of the Human Factors/Ergonomics specialty area is needed for ergonomics to successfully be incorporated into the business culture of today's corporations. Presented is a case study of the ergonomics efforts of a large financial corporation during the past three years. Included is information about internal partnerships, specific projects and successes (and failures), and a forecast for the future.
Explaining to a Jury how and Why People Fall
Authors: Thompson David A.
Published: January 2012

Human factors expert witnesses may be called upon to explain the mechanics of a particular physical falling event to a jury using only verbal, intellectual tools. Photos or diagrams of the falling event area usually show only the environment, not the human interacting with the environment during the critical falling event. The reconstruction the accident may be done with computer-generated 3-D mannequins to substitute for the humans involved in the falling event. This paper discusses the illustration of the mechanics of the falling process using 3-D mannequins to illustrate the laws of motion and of human behavior as accurately as possible.
Describing Faces from Memory: Accuracy and Effects on Subsequent Recognition Performance
Authors: Wogalter Michael S.
Published: January 2012

The present research examines: (a) the accuracy of three face description methods, and (b) the effects of post-exposure description and imaging activities on subsequent face recognition performance. Participants viewed a sequence of six target photographs, and after each, performed one of three description tasks: generated their own set of descriptors, checked-off descriptors from a pre-existing list, or rated the same set of descriptors on bipolar scales. Other participants performed a distractor (control) activity. Additionally, participants were either told or not told to image the targets while they simultaneously performed the description tasks. Results showed that the checklist task lowered subsequent recognition performance compared to the generate task. Imaging with the generate task facilitated recognition, but imaging with the checklist and rating tasks degraded recognition. The generate task produced the highest quality descriptions as determined by other participants' performance in matching the descriptions to face photographs. The checklist decrement is discussed in terms of memorial confusion initiated by the presence of irrelevant face cues. These results indicate that descriptor generation is the preferred method of collecting eyewitness' face descriptions.
Individual Differences in Driver Stress and Performance
Authors: Matthews Gerald
Published: January 2012

80 subjects high and low in vulnerability to driver stress participated in a study of simulated driving performance. Subjects completed the Driving Behaviour Inventory, which assesses vulnerability through a Dislike of Driving scale. Half the subjects performed in a ‘stress’ condition, in which they frequently lost control of vehicle steering, the remainder in a non-stressful control condition. Two performance measures were analyzed: response time (RT) on a secondary attentional task, and a measure of lateral tracking. The stress manipulation was more strongly related to longer RTs in high Dislike of Driving subjects than in low Dislike subjects. However, slowing of response was more pronounced on straight than on curved road sections, i.e. when the driving task is relatively undemanding. This finding suggests that stress-related impairment is not simply due to overload of attention. Instead, the stress-vulnerable driver may have difficulties in matching effort to task demands, with under-mobilisation of effort when the task appears relatively easy. Lateral tracking data were also consistent with this hypothesis. Self-report data suggested that the manipulation was generally effective in inducing subjective stress symptoms. However, high Dislike subjects tended to react to the manipulation with particularly high levels of intrusive thoughts and ‘cognitive interference’.
Task Effects on Three-Dimensional Dynamic Postures during Seated Reaching Movements: An Analysis Method and Illustration
Authors: Zhang Xudong , Chaffin Don B.
Published: January 2012

This paper presents a new method to empirically investigate the effects of task factors on three-dimensional (3D) dynamic postures during seated reaching movements. The method relies on a statistical model in which the effects of hand location and those of various task factors on dynamic postures are distinguished. Two statistical procedures are incorporated: a regression description of the relationship between the time-varying hand location and postural profiles to compress the movement data, and a series of analyses of variance to test the hypothesized task effects using instantaneous postures with prescribed hand locations as dependent measures. The use of this method is illustrated by an experiment which examines two generic task factors: 1) hand movement direction, and 2) motion completion time. The results suggest that the hand motion direction is a significant task factor and should be included as an important attribute when describing or modeling instantaneous postures. It was also found that the time to complete a motion under a self-paced mode was significantly different from a motivated mode, but the time difference did not significantly affect instantaneous postures. The concept of an instantaneous posture and its usage in dynamic studies of movements are discussed. Some understanding of human postural control as well as the implications for developing a general dynamic posture prediction model also are presented.
The Effect of Lifting vs. Lowering on Spinal Loading
Authors: Davis Kermit G.
Published: January 2012

In industry, workers perform tasks requiring both lifting and lowering. During concentric lifting, the muscles are shortening as the force is being generated. Conversely, the muscle lengthens while generating force during eccentric lowering. While research on various lifting tasks is extensive, there has been limited research performed to evaluate the lowering tasks. Most of the research that does exist on lowering has investigated muscle activity and trunk strength. None of these studies have investigated spinal loading. The current study estimated the effects of lifting and lowering on spinal loads and predicted moments imposed on the spine. Ten subjects performed both eccentric and concentric lifts under sagittally symmetric conditions. The tasks were performed under isokinetic trunk velocities of 5, 10, 20, 40, and 80 deg/s while holding a box with weights of 9.1, 18.2, and 27.3 kg. Spinal loads and predicted moments in three dimensional space were estimated by an EMG-assisted model which has been adjusted to incorporate the artifacts of eccentric lifting. Eccentric strength was found to be 56 percent greater than during concentric lifting. The lowering tasks produced significantly higher compression forces but lower anterior-posterior shear forces than the concentric lifting tasks. The differences in the spinal loads between the two lifting tasks were attributed to the internal muscle forces and unequal moments resulting from differences in the lifting path of the box. Thus, the differences between the lifting tasks resulted from different lifting styles associated with eccentric and concentric movements
Risk Factors and their Interactions in VDT Workstation Systems
Authors: Lu Hongzheng , Aghazadeh Fereydoun
Published: January 2012

This study examined important risk factors and their interactions associated with physical symptoms reported by VDT users. A research model was developed. A survey was designed and conducted among 88 computer users. The results show that risk factors associated with various physical symptoms are different. Screen glare, awkward working posture, and fatigue are important factors related to physical symptoms. Psychosocial factors significantly interact with other variables, such as demographics variables, and contribute to awkward work posture and psychological stress. Workstation design variables significantly affect working postures.
The Effects of Box Weight, Size, and Handle Coupling on Spine Loading during Depalletizing Operations
Authors: Marras William S. , Granata Kevin P. , Davis Kermit G. , Allread W. Gary , Jorgensen Mike J.
Published: January 2012

It is widely known that the order selection task in food distribution centers places the worker at risk of occupationally-related low back disorders (LBDs). One approach to controlling this risk consists of manipulating the characteristics of the object or box to be handled in the food distribution center. However, it is currently unknown what effect these changes to the box characteristics would have on the loading of the spine and the subsequent risk of low back disorder. Hence, the objectives of this study were to determine the change in spine loading at L5/S1 associated with selecting boxes that varied as a function of: 1) weight (40, 50, and 60 lbs), 2) size (2681 or 1584 cu. in.), and 3) the existence of handles or hand holds. In addition, these variables were explored as a function of where the box was on a pallet. Ten experienced order selectors were recruited from a local food distribution center and were evaluated as they selected boxes of different characteristics from a slot (bin) on to a pallet jack. Workers were monitored for their trunk motion characteristics as well as the EMG activity of 10 trunk muscles as they performed the task. The kinematic and EMG information was used as inputs to an EMG-assisted model that was used to predict the three-dimensional spine loadings that occurred during the task. The results indicated that conditions where a worker must reach to a low level of the pallet significantly increases spinal load. Thus, spinal loads were significantly great and only of a magnitude that would be expected to lead to low back disorders when workers lifted form the lowest layer of the pallet. Handles had the affect of reducing the spinal loading by an amount that was equivalent to a reduction in box weight of about 10 pounds. This effort has also facilitated our basic understanding as to why spine loading increases under the various conditions studied in this experiment. Nearly all differences in spinal loading can be explained by a corresponding difference in coactivation of the trunk musculature. This in turn significantly increase the synergistic forces supplied by each muscle to the spine and resulted in an increase in spinal loading.
A Data Base of Physically Demanding Tasks Performed by U.S. Army Soldiers
Authors: Sharp Marilyn A. , Patton John F. , Vogel James A.
Published: January 2012

The Department of Defense spends approximately one million dollars annually on research to enhance soldier physical performance (LTC K.E. Friedl, personal communication, Jan 1996). To most effectively direct this research effort, an accurate understanding of the physical demands of Army jobs is needed. The physical demands are available in printed form, however, there is no computerized means to quickly access and compile this information. The purpose of this paper is to describe the creation of a series of data bases containing the physically demanding tasks of Army occupations and to provide a preliminary summary of a selected data base.
An Ergonomic Evaluation of a Drywall Board Transport Handle: Single-Person Transport Task
Authors: Stuart Mark A. , Zellers Kerith K.
Published: January 2012

The objective of this study was to determine how the use of a drywall board transport-handle affects physical stress on the human body, subjective reports of pain, discomfort, and physical exhaustion, and task performance compared to a no transport-handle condition. Eight construction workers lifted and transported 20 drywall boards in a simulated single-person construction task. Results indicated that there were no significant differences between the two board transport conditions on any of the subjective and physical data collected. Average task performance times were slower for the handle-use condition (232 seconds compared to 207 seconds), but this difference was not statistically significant. A serious shortcoming of the transport handle evaluated in this study is that it does not eliminate the major risk factors associated with drywall installation: frequent lifting and carrying of very heavy objects, and awkward postures of numerous types. Drywall installers' work-related musculoskeletal disorders will likely continue as long as commercial construction continues to require single-person board lifting and transporting and as long as the boards stay as large and heavy as they are currently.
An Interface Agent for Retrieval of Patient-Specific Cancer Information
Authors: Zachary Wayne , Szczepkowski Michael A. , Le Mentec Jean-Christophe , Schwartz Stanley , Miller Darius , Bookman Michael A.
Published: January 2012

PDQ and CANCERLIT are databases that represent potentially valuable resources for oncologists, but there are significant obstacles to their effective use in the clinical context. The clinician must learn where each database can be found, what it contains, and how to query it. More importantly, the clinician must also determine when and how each information resource is appropriate to the (clinical) task at hand, and integrate their general information with patient-specific data contained in patient records and clinical information systems. This research sought to remove these barriers to information use by developing a software agent in the human-computer interface that automates the information retrieval and integration process. The agent, developed from a cognitive model of how human experts perform these tasks, provides both a specific solution to the cancer information access problem, and a template for solving similar problems that occur with increasing frequency in many other domains.
Collaborative Systems Research: Establishing Ecological Approaches through the Living Laboratory
Authors: McNeese Michael D.
Published: January 2012

Today's work may very well encompass team work through direct contact with other workers. However, an evolution in the way we work together is taking place. The INTERNET, groupware, video teleconferencing, and distance learning are just some of the examples of collaborative technologies being inserted in the marketplace. Real world environments still include face-to-face transactions but now increasingly encompass distributed electronic transactions facilitated through computing / video media. Human factors - as an interdisciplinary science - may not have been sufficiently developed to move toward a macro-view of collaborative technology. As a result, human factors analysis of ‘team error’ may have been nearsighted and shallow. Also such analyses -if completed at all- tend to emanate from a traditional cognitive psychology bias. In turn, the paper develops an alternative perspective utilizing ecological psychology to study and interpret human interaction within collaborative systems. From that perspective, the creation of a “Living Laboratory” is explored whereupon three paradigms to study collaborative processes are presented. Associated assessment tools (e.g., concept mapping and protocol analysis) are discussed as catalysts to synergize this perspective. Implications highlight the ‘Living Laboratory’ as a vehicle to inform the development of a prototype ecological group interface.
Sociotechnical Design Factors for Virtual Team Performance
Authors: Cano Arnoldo R. , Kleiner Brian M.
Published: January 2012

Recent developments in communication and information technology, coupled with an increased need to coordinate organizational activities across geographically dispersed locations, have led to the development and use of virtual teams. Evidence, most of it anecdotal, points to the benefits that can be obtained from the use of such teams. Unfortunately, a comprehensive understanding of the factors that affect virtual team-based system performance is lacking due to little empirical evidence and sound theory. In this paper, sociotechnical systems theory is used to identify design factors for virtual team performance.
Perceptions of Risk Associated with Drinking Alcoholic Beverages
Authors: McQuilkin Meredith L. , Laughery Kenneth R. , Lowoll David R.
Published: January 2012

This study explored people's perceptions of risk associated with drinking alcoholic beverages before driving. Subjects rated the level of hazardousness of driving after consuming two, four, or six drinks of beer, wine, or hard liquor during a one, two, or three hour time frame. Differences in perceived hazard were found between the types of beverage consumed. Specifically, hard liquor was perceived as being more hazardous than both beer and wine. As expected, perceived hazard levels increased as the number of beverages consumed increased, and, as the time period increased, the average hazard rating decreased. For example, four drinks in three hours were perceived as less hazardous than four drinks in one or two hours. Generally, people perceive two drinks to result in a less than moderate driving hazard when consumed in a short time frame, while four or more drinks are perceived to be a hazardous level of consumption for driving.
Differences in the Evacuation Behaviour of Office and Apartment Building Occupants
Authors: Proulx Guylène , Pineau Joelle
Published: January 2012

An experiment was designed to observe evacuation times and occupant movement in two office buildings during a simulated fire emergency and to compare these results with previous studies of evacuation drills in apartment buildings. The evacuation drills were recorded using videocameras located throughout the buildings. The results were analyzed with respect to occupant behaviour, occupants' time to start to evacuate, occupants' time to reach an outside exit, and the occupants' speed while travelling in the stairways. A comparison of the results from this office buildings study with previous studies involving evacuations of midrise and highrise apartment buildings reveals many interesting differences. The physical organization of the buildings, evacuation strategies, and the occupants' characteristics, behaviour and movement are discussed.

The study showed that apartment building occupants delay their evacuation more than office building occupants, either by a long preparation time or because they cannot hear the alarm from their apartments. Travelling speeds are slowest in midrise apartment buildings where the population is more diverse and includes children, elderly people and occupants with limitations. The more structured evacuation plans, the presence of fire wardens and the easier access to fire safety information also contribute to the efficiency of evacuation procedures in office buildings.
How Subject and Experimenter Variables Influence Estimates of Hearing Protector Attenuation Using Ansi-Standardized Testing Procedures
Authors: Mears Mark G. , Casali John G. , Franks John R.
Published: January 2012

Hearing threshold levels (HTLs) were determined using audiometrically-normal subjects with and without earplugs for two hearing protection device (HPD) laboratory fitting protocols. The experimenter-fit (EF) protocol intended to estimate the optimum attenuation of an HPD. EF involved a high level of experimenter participation and a low level of subject participation—the experimenter optimally fit earplugs to the subject. The subject-fit (SF) protocol, on the other hand, intended to estimate the more typical attenuation achievable in the real-world by well-run hearing conservation programs (HCPs), therefore, inexperienced-in-HPD-use subjects fit one of two types of earplugs on themselves using only the manufacturer's on-package instructions and without experimenter assistance. The objective was to compare the attenuation performance of the two HPD fitting protocols which varied in subject and experimenter testing participation and involvement. As expected, significantly greater attenuation resulted under EF than SF. Comparisons of the SF data to real-world studies demonstrated that SF slightly overestimated real-world attenuation, but not by nearly as much as EF. Therefore, SF better estimated the level of noise protection likely to be afforded to actual HPD users. The factors of subject gender and number of trial repetitions per subject were studied as well but did not significantly affect HPD attenuation. The results supported the work currently underway by ANSI Working Group S12/WG11 to develop a new ANSI standard to be used for obtaining attenuation data for labeling purposes which recommends the SF procedure.
Measuring Perceived Urgency to Create Safe Auditory Warnings
Authors: Haas Ellen C. , Edworthy Judy
Published: January 2012

Various pulse parameters, which were believed to affect the perceived urgency of multitone auditory warning signals, were investigated in a factorial experiment. The three independent variables included pulse fundamental frequency (200, 500, and 800 Hz), pulse sound pressure level above ambient (5, 25, and 40 dB sound pressure level [SPL]), and inter-pulse interval (0,250, and 500 ms). The psychophysical method of free-modulus magnitude estimation was used to measure subjective perceived urgency. Multivariate statistical analysis indicated that all independent variables and most variable interactions were significant. Perceived urgency increased as pulse level increased and inter-pulse interval decreased. Multidimensional scaling analysis indicated that signal level and inter-pulse interval were important in subject perception of signal similarity in terms of perceived urgency. Signals with high sound pressure levels and short inter-pulse intervals were perceived by subjects to have similar perceived urgency, as were signals with low sound pressure levels and long inter-pulse intervals.
A Tactical Decision Support System Based on Naturalistic Cognitive Processes
Authors: Moore Ronald A. , Quinn Michael L. , Morrison Jeffrey G.
Published: January 2012

An advanced decision support system has been developed to facilitate Navy tactical decision making, particularly in stressful and high workload environments. The system is unique in that it builds upon cognitive theories and adopts user-centered design and testing approaches. The theoretical basis and operational rationale behind each of the modules of this composite display system are discussed.
Sound Localization: Information Theory Analysis
Authors: Wallace John S. , Fisher Donald L. , Collura John
Published: January 2012

Three experiments were performed which examined the applicability of the Hick-Hyman law to the design of an auditory interface for a vehicle collision avoidance warning system. All trials used a single broadband noise signal emanating from one of a subset of six loudspeakers equally spaced around the subject in the azimuthal plane. Both the size of the sub-set and the balance of relative probabilities from speaker to speaker were altered to evaluate the relationship between information content and the dependent variable, choice reaction time. Choice reaction time was found to be related to the information content of the sound stimulus in all cases. It was also found to be related to the presence of pairs of speakers which were symmetrically opposed to one another in front of and behind the subject.
Older Commercial Vehicle Drivers: Abilities, Age, and Driving Performance
Authors: Llaneras Robert E. , Swezey Robert W. , Brock John F.
Published: January 2012

This research reports upon a series of related studies which involved investigations of fifteen human abilities, their changes which occur with aging, and their effects upon commercial truck driving performance. One-hundred and seven commercially licensed truck drivers, divided into five age cohort groups, participated in the research study. An ability testbed was used to measure 15 driving related perceptual, cognitive, and psychomotor abilities. Driving performance was assessed using an interactive commercial truck driving simulator. Relationships between perceptual, cognitive, and psychomotor abilities and measures of driving performance indicated that functional levels on these tasks and driving performance were significantly related; however, age, in and of itself, was not predictive of driving performance.
Operator Experience and Accident Risk
Authors: Ayres T. J. , Lau E. C. , Schmidt R. A. , Young D. E.
Published: January 2012

It has long been recognized that the risk of operating motor vehicles declines as operator experience increases, even when operator age is deconfounded. In this paper, causal analyses of accidents involving all-terrain vehicles (ATVs) are reviewed in order to explore the role of experience in accident patterns. Factor attributions made by evaluators from the U.S. Consumer Product Safety Commission were sorted according to the reported ATV experience of the person operating each vehicle at the time of an accident. Counter to some expectations, the proportion of accidents attributed at least in part to each major category (e.g., operator, mechanical, or environmental factors) did not change appreciably with operator experience. In addition, most of the proportions attributed to each of a series of possible operator-related factors did not change, with several generally expected exceptions. Implications for understanding and reducing accidents are considered.
Fatigue and Trucking Accidents: Two Modes of Accident Causation
Authors: Young Stephen L. , Hashemi Lobat
Published: January 2012

The U.S. National Transportation Safety Board investigated 113 heavy-truck accidents to determine “the role of specific factors, such as drivers' patterns of duty and sleep, in fatigue-related heavy truck accidents” (NTSB, 1995a). For a number of reasons, we believed that a re-analysis of this data, with a different set of variables, might yield a more complete picture regarding the nature of fatigue-related accidents and their causes. Specifically, principal components analysis was employed to determine the underlying factors that contributed to accidents where fatigue was determined to be the primary cause. In this analysis, two principal components were extracted that dealt with (1) the nature of the driver's sleep periods and level of experience, and (2) aspects of the driver's work periods. Subsequent cluster analysis demonstrated that the cases could be divided into two distinct accident modes or types: those with and those without regular sleep/work patterns. Drivers with generally regular sleep/work patterns appeared to develop fatigue while on the job, while those with irregular sleep/work patterns appeared to arrive at the job already fatigued. In conclusion, the variables which contributed to fatigue in the NTSB report were found to contribute to fatigue in the present analysis, but not to the same extent in all cases. Some of the variables that influenced driver fatigue in one of the clusters (or accident modes) had no effect on the other. These different accident modes should be considered when examining the effect of a given variable on fatigue.
Human Systems Integration (HSI) in Navy Ship Manpower Reduction
Authors: Bost J. Robert , Malone Thomas B. , Baker Clifford C. , Williams Charles D.
Published: January 2012

The HSI approach to ship and ship system design for manning reduction is based on the standard human factors front-end analysis to identify functions and requirements, allocate functions to determine the role of the human vs. automation, identify approaches to reduce workload, and conduct task network workload simulation to establish the effectiveness of selected workload reduction techniques. The classes of workload reduction are focused on design requirements associated with automation of functions, consolidation of functions, simplification of function performance, and elimination of functions. Function Automation addresses the automation of functions previously performed manually and the determination of the roles of the human in automated or semi-automated functions. Function Consolidation requires a reassignment of functions among available operators to more evenly redistribute required workload. Function simplification requires that, for high driver functions and tasks assigned to a specific operator or maintainer, the demands that these functions and tasks make must be reduced to the greatest extent possible. Function/task demands include physical, cognitive, and perceptual-motor demands. Function Elimination involves removing a function from the ship through tele-operations or tele-maintenance with shoreside equipment tech-reps or maintenance experts, and reliance on collaboration tools to support dispersed team problem solving, or elimination of a function altogether.
Human Factors Challenges for Advanced Process Control
Authors: Stubler William F. , O'Hara John M.
Published: January 2012

New human-system interface technologies provide opportunities for improving operator and plant performance. However, if these technologies are not properly implemented, they may introduce new challenges to performance and safety. This paper reports the results from a survey of human factors considerations that arise in the implementation of advanced human-system interface technologies in process control and other complex systems. General trends were identified for several areas based on a review of technical literature and a combination of interviews and site visits with process control organizations. Human factors considerations are discussed for two of these areas, automation and controls.
Alphanumeric Data Entry and Editing on a Telephone-Type Keypad
Authors: Riley Daniel D. , Glenn Floyd A.
Published: January 2012

Innovative alphanumeric data entry and edit procedures are required for input-output devices that, constrained by size and usage considerations, are limited to functionality available with multi-character and limited function keys. Such an interface was developed by the authors for Martin Marietta in support of the US Army Single Channel Anti-jam Man-Portable (SCAMP) Program. Two character entry schemes and three message editing protocols were developed and evaluated using a Macintosh-based, Supercard-configured prototype whose conventions were assessed by twelve subjects in a counter-balanced experimental design. One character entry scheme proved to be statistically superior to the other scheme in terms of time and number of keystrokes required, and was universally favored by subjects. Although there was no clearly superior message editing protocol among the three alternatives, one convention was generally favored over the others in terms of performance and ease of operation.
Feasibility of a Portable Data Acquisition System for Driver Performance Testing
Authors: Carter Richard J. , Spelt Philip F. , Barickman Frank S.
Published: January 2012

A research program oriented toward the development of a portable data acquisition system for driver performance testing was conducted. This paper describes three tasks which were performed during phase I of the research, namely, identification of parameters that should be measured and definition of the minimum set of parameters, development of design requirements for the data acquisition system, and identification of the data storage and transmission architecture.
The Use of Interobserver Methods in System Tests: A Methodological Case Study
Authors: Clarke David L. , Beith Barry H.
Published: January 2012

An interobserver approach to conducting a system test is presented in a case study to promote this methodology for human factors practitioners. A system test of a specific feature of a commercially available VCR was performed under a contract. This special feature was designed to automatically fast-forward through recorded commercials during playback. Two specific measures of system performance required under this contract were the accuracy in skipping commercials and the accuracy in not interfering with regular programs during playback. In order to obtain a high level of reliability and validity at a relative low cost, an interobserver methodology was used to measure the accuracy of the VCR commercial skip feature. This method entailed having pairs of observers from a group of ten observers analyze 52 videotapes for commercial and program errors, comparing and reconciling their data, assessing interobserver reliability, and using the means of their observations to calculate accuracy rates. The benefits of multiple observer accuracy measures are discussed.
Subdivision of Grading Units Can Increase the Reliability of Performance Testing
Authors: Harris Douglas H.
Published: January 2012

This study examined the effect of subdividing grading units on performance test reliability. That is, instead of increasing test length by adding grading units comparable to existing grading units, this experimental approach attempted to increase test length, and hence reliability, by subdividing existing grading units into comparable subunits. The effect of subdividing grading units was assessed empirically using a performance test of the ultrasonic detection of cracks in pipe welds. Five-hour performance tests involving the examination of 10 pipe-weld specimens were completed by each of 52 experienced ultrasonic operators as part of their qualification for performing tasks of this type in nuclear power plants. Subdivision of grading units was found to increase the reliability of the test from 0.28 to 0.92, to decrease the standard error of measurement of the test from 13.81 to 1.35, and to decrease the 90% confidence band around test scores from ± 22.60 to ±2.20. Moreover, the increased reliability was predicted by the Spearman-Brown Prophecy Formula, the method commonly employed for predicting the effect of increased length on test reliability.