bluuebunny/crossref_metadata_2025 huggingface dataset:
Designing for Change: Dynamic Communications Using a Logical Model
Authors: McMillen L. D. , Fisk A. D.
Published: January 2012

The Human Factors Engineer is often called upon to perform tasks requiring a substantial amount of interviewing for workflow data gathering. This is certainly the case when a new EDP system is being investigated/restructured or when the manual workflow of an organization is being investigated. The Human Factors objective, in this sort of workflow analysis is to maximize the efficiency of any change and minimize the disruption (during and after the investigation) to the personnel involved. A careful task and workflow analysis must be performed since simply replacing manual tasks with a computer will not necessarily result in efficient workflow or task performance. The analysis must include the entire universe of tasks that are or could be performed in order to determine the information flow, when to remove from or insert the human in the mechanized system loop, etc.

The present paper describes a methodology for building what we refer to as a logical model of both the user and system environments. Often, the only certainty facing system designers and Human Factors Engineers is change in the work environment and in the use of the EDP systems supporting that work. It makes sense then to build into the design of the work environment and EDP systems the greatest flexibility and modularity possible. The present paper describes how, by using the proposed logical model methodology, the Human Factors Engineer becomes the “agent of change” on any development team.

The improved analysis and design methodology contains five major activity steps which lead to the creation of a working logical model. These activity steps are: 1) Identification of the working environment; 2) Establishment of the organization and system scope: 3) Development of a functional hierarchy; 4) creation of work and data flows; and 5) Documentation of each identified work and system module. Each step is illustrated and described in detail in the paper. Also, how each step, by its and in coordination with the other steps, is used to build the working logical model is discussed.

The paper describes the methodology in an instructive manner. Drawing from experience gained by utilizing the methodology, the advantages and disadvantages are highlighted. Any design methodology, however useful, is dependent on the willingness and commitment of all team members to implement it. The steps taken to gain broad acceptance of the methodology are discussed within the paper.

In essence, the logical model can be used by the Human Factors Engineer as a dynamic communication device providing two way communication between designers, implementors, and user organizations. As design options in system development become available the Human Factors Engineer can demonstrate the impact of the options. Also, newly discovered user requirements can be added to the model and communicated to the designers.
Empirical Investigation of Aids for Non-Programming Users in Developing Cost Effective Requirements Specifications
Authors: Connelly Edward M.
Published: January 2012

The difficulties of the non-programming user in developing quality software-requirements specifications are well known and described in the literature. Typically, the user will work with a software expert to develop the specifications. During this process the user must learn new terms and concepts, and must attempt to identify the required functions of the resulting software product.

The goal of this investigation was to evaluate the capability of non-programming users (in this case experienced inventory managers) to develop specifications for an inventory error-control system. Participants specified tests from a set of available tests to detect possible errors in inventory change-records, i.e., in inventory updates. Costing-aids were provided that were analogs of aids that are expected to be presently available. The costing-aids provided an increasing data on system cost: the total system cost, the total system cost plus the costs of each part of the system, and an automatic sort of previous designs according to cost.

Results shewed that problem-complexity had a strong effect on performance; greater problem-complexity resulted in more costly designs. Further, the more complete costing-aids tended to degrade performance on the simple problems, yet they improved performance on the more complex problem. It was concluded that the ability of non-programming users to develop least-cost requirements specifications was poor when using any of the aids that were made available. The experimental results, however, suggested new approaches for procedural and computational support for the non-programming user, that could lead to more suitable costing-aids.
Product Information Presentation, User Behavior, and Safety
Authors: McCarthy Roger L. , Finnegan James P. , Krumm-Scott Susan , McCarthy Gail E.
Published: January 2012

A review of approximately 400 published articles, in addition to the authors' own research in the area of on-product warning label design and effectiveness, is summarized. Findings are examined for implications in the design and use of on-product warning labels for improved product safety through modification of user behavior. No scientific evidence was found to support the contention that on-product warning labels measurably increase the safety of any product. There was evidence that on-product warnings have no measurable impact on user behavior and product safety.
System Safety Approach to Robot Safety
Authors: Rahimi Mansour
Published: January 2012

The need and importance of considering robot safety issues are emphasized. Based on previous researches, major categories of robot accident causes are identified and listed. System safety is described as an appropriate approach to evaluating and designing robot safety systems. Then, qualitative and quantitative system safety techniques are introduced. Energy barrier analysis (a qualitative model) is selected and applied to a general human-robot system. Finally, as a result of this application, specific solutions and recommendations are discussed.
Sign Luminance Requirements for Various Background Complexities
Authors: Mace Douglas J.
Published: January 2012

The effects of retroreflective luminance on the recognition of traffic signs at night is mediated through contrast with the immediate surround. Additionally, complex visual scenes are known to degrade visual performance with respect to signs well above visual threshold. A series of laboratory and field studies were conducted to develop a technique for measuring nighttime visual complexity and to assess the capability of increased sign luminance to offset the performance decrement resulting from added complexity. Positive results were obtained for a variety of signs. A limited field validation suggested that degraded luminance may be adequate when complexity is low, but the highest levels of luminance may not be adequate at high complexity locations.
A Study of Programmable Switch Symbology
Authors: Hawkins James S. , Reising John M. , Woodson Brian K. , Bertling Samuel J.
Published: January 2012

A multifunction switch is one way to solve the diminishing real estate problem in the modern cockpit. This study looked at pictorial coding of such a switch. Twelve different symbols were used, each with three levels of complexity and two levels of polarity. An error rate count was taken for subjects under both a naive and learned 50 millisecond exposure condition. This study demonstrated that there were three classes of symbols. These were: intuitive to the naive subject, intuitive to a learned subject, and non-intuitive, even to a learned subject. Complexity levels had a significant effect in only three of the twelve symbols. Polarity differences also had a significant effect in only three of the twelve symbols, although they were a different three. The overall conclusion is that the majority of symbols were intuitive after learning and robust to changes in complexity and polarity.
The Effects of Simulator and Aircraft Motion on Eye Scan Behavior
Authors: Comstock James R.
Published: January 2012

In a series of three experiments on the effects on eye-scan behavior of both simulator and aircraft motion, the sensitivity of an oculometric measure to motion effects was demonstrated. “Fixation time”, defined as the time the eyes spend at a particular location before moving on (saccade) to another fixation point, was found to be sensitive to motion effects in each of the experiments conducted. The results of the present study support the hypothesis that motion serves an alerting function, providing a “cue” or “clue” to the pilot that “something happened”. The results do not support the hypothesis that direction of motion is conveyed through the type of motion information employed in these experiments.
Software Ease-of-Use Evaluation Using Magnitude Estimation
Authors: Cordes R. E.
Published: January 2012

Two software usability studies were conducted that used magnitude estimation (line production) in an ease-of-learning comparison of the command and panel-entry interface of the IBM Hierarchical Storage Manager (HSM), Release 3.2 program product. The first study revealed a number of user-interface problems with the prototype panels, which were then corrected in the released product. The second study verified that these changes significantly improved the panel interface of HSM. Both direct and indirect comparisons were used in the evaluations and a power function showing the relationship between perceived difficulty and task-completion time was reported.
A Methodology for Determining Terminal Characteristics
Authors: Fischer Sharon G.
Published: January 2012

This paper presents a methodology developed for determining terminal characteristics. The methodology is based on work performed for the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC). Specifically, this work was part of a task to provide human factors support to the development of the Network Control Center (NCC). The overall system engineering methodology used for system development was CSC's Digital System Development Methodology (DSDM) (CSC, 1984). The methodology developed for determining terminal characteristics is an extension of CSC's general methodology.
Design and Validation of a Checklist to Aid in Choosing Word Processor Software
Authors: Mosier Jane N.
Published: January 2012

A checklist was designed to evaluate software usability. Then, to determine whether it was possible to collect the required data, the checklist was used to evaluate two different word processors. Finally, users of those two word processors were interviewed to determine whether their views of the strengths and weaknesses of each word processor matched the strengths and weaknesses indicated by the evaluation checklist. It was concluded that the checklist is both useful and usable.
Ergonomics Lab Experiments for Industrial Engineering Sophomores
Authors: Adams S. Keith
Published: January 2012

A sophomore-level course in ergonomics (IE 274, Ergonomics in Work System Design, 2 semester hours) is the only course in ergonomics required by undergraduate industrial engineering students at Iowa State University. Providing a set of meaningful, two-hour laboratory experiences for sections of 20 to 25 students in a room also used for other course laboratory work in the same day has proven to be a challenging educational project. Laboratory exercises developed and used so far are described along with plans for future developments and implications for the potential expanding role of ergonomics in industrial engineering education.
Some Considerations in the Design and Implementation of a Training Device Performance Assessment Capability
Authors: Hawley John K.
Published: January 2012

In an era of increasing system complexity and resource constraints, live-fire exercises on a scale necessary to insure personnel proficiency are not feasible for many weapons systems. A partial solution to the problem of insufficient performance evaluation involves the use of training devices in lieu of operational equipment in the conduct of evaluation exercises. A trainer that has been extended to include an embedded performance evaluation capability is referred to as a training device performance assessment capability (DPAC). The present paper presents a series of guidelines for the design and development of DPACs. The guidelines were prepared on the basis of background research and actual experience in developing a DPAC for the Patriot air defense missile system. Because of their association with an actual developmental effort, the guidelines have considerable practical utility for DPAC design and implementation. A number of issues important for the full realization of DPAC potential also are discussed.
The Effects of Supervisor Experience and the Presence of a Shift Technical Advisor on the Performance of Two-Man Crews in a Nuclear Power Plant Simulator
Authors: Beare Arthur N. , Dorris Roy E.
Published: January 2012

This report describes a training simulator experiment to evaluate the effects of the experience level of the Senior Reactor Operator (SRO) and the presence of a Shift Technical Advisor (STA) on the performance of nuclear power plant control room crews.

Sixteen two-man crews of licensed operators were employed in a 2 × 2 factorial design. The SROs leading the crews were split into “high” and “low” experience groups on the basis of their years of experience as an SRO. One half of the high- and low-SRO experience groups were assisted by an STA or an SRO acting as an STA. The crews responded to four simulated plant casualties. A five-variable set of content-referenced performance measures was derived from task analyses of the procedurally correct responses to the four casualties. System parameters and control manipulations were recorded by the computer controlling the simulator. Data on communications and procedure use were obtained from analysis of videotapes of the exercises. Questionnaires were used to collect subject biographical information and data on subjective workload during each simulated casualty.

For four of the five performance measures, no significant differences were found between groups led by “high” (25–114 months) and “low” (1–17 months as an SRO) experience SROs. However, crews led by “low” experience SROs tended to have significantly shorter task performance times than crews led by “high” experience SROs. The presence of the STA had no significant effect on overall team performance in responding to the four simulated casualties.
Effects of Keyboard Design and Typing Skill on User Keyboard Preferences and Throughput Performance
Authors: Brunner Hans , Richardson Rose Mae
Published: January 2012

A study was conducted to compare user preferences and throughput performance on 3 prominent keyboards with 3 different kinds of key action mechanisms. Preference and throughput data were obtained from both skilled (>65 WPM) and occasional (30–50 WPM) typists. Both groups of typists indicated about equal preference for keyboards with snap-spring and elastomer key actions and much lower preference ratings for the keyboard with a low-resistance, linear spring key action mechanism. Fewer errors and faster typing throughput were obtained on keyboards with the elastomer key action than on the other two keyboards, equipped with snap- and linear-spring key action mechanisms. This facilitation was greater for the occasional typists than for the experts. The reverse interaction was obtained for electronic key click, which produced much larger increases in real throughput for experts than the occasional typists.
Eye Hazard Areas/Jobs: An Integrated Approach to Eye Protection
Authors: Schmidt John K. , Petree Barry L. , McDaniel James P.
Published: January 2012

Safety Associations have advocated the use of eye protection on a hazard-area basis. A series of scenario analyses were performed on 448 eye injury cases, which occurred over a two year period in a southwestern petro-chemical manufacturing complex, in order to examine the effectiveness of this policy. The resulting patterns indicated that the majority of workers, who had incidents, complied with the area based protection policy and still suffered injury (95.1%). Subsequent analysis indicated that a moving object, usually in the form of debris, was the major source of injury (74.3%) and the remaining cases were a result of fluid contact (24.6%). The results suggest that various types of debris and fluids are able to circumvent designated protective devices due to inadequacy, improper wear and/or unforeseen hazards. It is suggested that an integrated application of eyehazard area and job protection would provide for situations where specific tasks within an already established eyehazard environment would produce hazardous conditions not covered by present policy.
The Effects of Redundancy, Target Density and Practice on a Complex Visual Search Task
Authors: Patterson Michael J. , Engelman William J. , Najjar Lawrence J. , Corso Gregory M.
Published: January 2012

A major problem in the use of visual displays is the efficient transmission of information during critical periods of time. Recent studies examining display configurations have investigated increasing information transmission (e.g., vertical separation) through modification of display presentation formats. However, the results have been equivocal. The present investigation attempted to evaluate a simulated air traffic format using multi-dimensionally coded target situations. The relevant dimensions were color and alphanumeric characters. Search performance of a near miss situation of two aircraft as a function of type of code (chromatic/achromatic), density (high/low) and practice was investigated. The required response was the identification of the quadrant containing the near miss situation. Search performance was measured by the time required to locate the near miss situation and the number of correct responses. Differences in performance between coding conditions were found for the number of correct responses. A significant effect was observed for the response time as a function of display density. Results are discussed in reference to current research utilizing dynamic displays and multidimensional coding.
Color Coding of Synthetic Aperture Radar Imagery
Authors: Ward Frank , Wilson Denise , Wallquist Donald , Kuperman Gilbert
Published: January 2012

The purpose of our study was to investigate four types of coding strategies using the same Synthetic Aperture Radar (SAR) imagery. We digitized unclassified SAR imagery to include scenes from urban areas, seaports, oil refineries, industrial sites, an airfield, and power transmission lines. Two color and two black and white (BW) coding schemes were applied to the imagery. Five experienced radar interpreters were briefed and viewed 35 mm slides of the imagery. They judged image usefulness by reference to an interpretability scale. Analysis of the ratings showed that the BW codes received significantly higher interpretability ratings than the color codes.
An Assessment of Four Cockpit Displays
Authors: Wozniak William , Gardner Daryle J. , Lienert Jeanette , Gokie Steven
Published: January 2012

Three experiments assessed four types of aircraft cockpit displays. One display was a circular format whereas the other three were vertical formats. Of the three vertical displays, one had a moving pointer, the remaining two had vertical bars whose length indicated engine status.

The stimuli were prepared on 5 × 5 cm slides. Each slide portrayed either 2, 3, or 4 engines using a particular display-type. On any slide, exactly one of these engines was out of tolerance, i.e., above or below a particular level. Half of the slides were prepared with one engine above tolerance, and half with one engine below. Subjects were instructed to view each slide and report which engine was out of tolerance. Response time and errors were the dependent measures.

Experiment One showed that vertical formats with moving bars lead to the best performance, followed by a vertical format with a moving pointer. Poorest performance was observed for the circular displays.

Experiment Two assessed the four display-types under conditions of good or poor discriminability (clear-cut or borderline.) In the borderline conditions, all engine readouts were within 10% of the total display distance from the tolerance line. In the clear-cut conditions, the readouts were at least 25% of the total display distance from the tolerance line. The pattern of results seen in Experiment One was seen in both the clear-cut and borderline conditions of Experiment Two.

Experiment Three assessed the displays over five days of extended practice. Again, the same pattern of results revealed itself. Over the five days, both response time and errors reflected improved performance. However, on day five, errors were not completely eliminated in the circular display-types and in the vertical display-types with moving pointer. Errors were eliminated for the other displays.

The relative efficacy of each display-type are discussed with regard to number of engines, discriminability of readouts, and practice.
Scaling Military Symbols: A Comparison of Techniques to Derive Associative Meaning
Authors: Knapp Beverly G.
Published: January 2012

The use of symbolic representations of concepts is explored in the context of their inherent, associative meaning. Several symbol sets in military use were evaluated using two scaling techniques, ratings and pair comparisons. Findings validate a model of symbol categorization proposed by Modley (1966) and provide implications for the use of ratings vs. pair-comparisons in evaluating symbols.
Design of Organizations and Jobs: Sociotechnical Principles and Japanese Practice
Authors: Robinson Gordon H. , Nadler Gerald
Published: January 2012

Principles for the design of jobs and organizations have evolved from both theory and experiences in the application of sociotechnical and “quality of work life” concepts. In parallel with this development, the Japanese have put in place some organizations that perform well and have quite distinctive features from those generally seen in the U.S. This paper examines some of the Japanese designs in the context of the “Western” sociotechnical theory.
Modeling Organizational Design: Resource Allocation in a Military Application
Authors: Sehwalm Robert C.
Published: January 2012

Whenever resource availability and resource costs are limiting factors in organizational design, it is essential that organizational design decisions be based upon the effective and objective allocation of those limiting resources. Two computer-based simulation models are discussed as instruments to facilitate this process. Both are based on a realistic assessment of mission needs and resource availability. The ARI Crew Performance Model considers the impact of crew size and the assignment of tasks on crew performance. The Analysis of Military Organizational Effectiveness (AMORE) assesses the capability of a unit to perform over time after degradation. Together these models, which can be applied to both military and non-military systems, promote the efficient and objective organization and use of resources at the crew level and higher.
Conserving Instructional Training Resources through Use of the Personalized System of Instruction
Authors: Wick Daniel T. , Ruffner John W. , Bickley William R.
Published: January 2012

Training managers in the U.S. Army face a continuing problem of meeting increasing training demands with limited instructional resources, particularly qualified training personnel. In most aviation unit flight training programs, instructor pilots (IPs) serve a dual role of academic lecturer and in-the-cockpit instructor. To reduce the amount of IP time required to administer training in a reserve aviator training program, a 19-day training program was developed that incorporates home study and features of the Personalized System of Instruction (PSI). Forty-seven aviators were trained using this program. Following one year of no training, 24 of the aviators returned for refresher training using the same program. The results indicate that the home study/PSI approach reduces on-site academic training time and virtually eliminates IP time on academic topics. The results also suggest that an academic training program based on PSI can be used successfully while conserving the scarce instruction resource of IP time.
An Optimization Model of Self-Paced Tracking
Authors: Montazer M. A. , Drury Colin G.
Published: January 2012

A model which describes human performance in a self-paced tracking task was developed based on the notion that human operators are intermittent-acting or sampled-data servo-mechanisms. The model had a functional form in terms of the probability of success and failure resulting from the execution of a manual control task such as drawing a line between fixed boundaries. The human operator was modelled as an optimizer, balancing costs and penalties of speeds and errors to achieve a maximum expected payoff. The performance of the model was evaluated by simulating a line drawing task on a digital computer. Model predictions obtained via simulation were compared with the data collected from human subjects performing the actual task in a laboratory setting. The predictions of the model were confirmed, suggesting that human operators can in fact be modelled as optimizers when performing a manual control task.
Validation of a Fuzzy Model for the Assessment of Human Operator Responses to Manual Lifting Tasks
Authors: Karwowski Waldemar , Mital Anil
Published: January 2012

A fuzzy model for the assessment of lifting stresses imposed on the human operator was validated based on the experimental data collected on experienced male workers. Conditions were re-examined for which acceptabilities of the combined physiological and biomechanical stresses were similar to the psychophysical stress. It was shown that the ‘standard’ fuzzy model can be effectively extended to the industrial population.
Window Design for a Professional Workstation in the Office Environment
Authors: Murray J. Thomas , Hakkinen Markku T. , Mackraz James D.
Published: January 2012

This presentation describes the development of the user interface for a windowing system implemented on a multi-tasking professional workstation used in the office environment. The project was completed under severe schedule restrictions which impacted the implementation tradeoffs for user interface design.

The functional and user interface goals for the windowing system were as follows:

• The user should be able to subdivide the screen with a different application running in each window. • The user should be able to quickly and easily move between open windows/applications. • Operation of an application within a window should be the same as when the application is full screen. • The user should be able to quickly alternate between a partial view and a full-screen view of an application.
Bent Hammer Handles: Performance and Preference
Authors: Konz Stephan , Streets Brad
Published: January 2012

Sixty male students drove 10 nails with each of three hammers (0° bend, 10° bend and 15° bend). Handle angle did not significantly affect the depth the nails were driven, or the angle of the nail in the left-right direction. The mean front-to-back nail angle of .3° for the 0° bend handle was significantly different from the −1.1° for the 10° handle and the −1.2° for the 15° handle. There was a significant preference for the 10° handle; the vote of 121% for the 10° handle was significantly higher than the 100% for the 0° handle and the 97% for the 15° handle.
Recreating a Database for Consumer Product Design
Authors: Formosa Daniel
Published: January 2012

Product evolution can often lead to degradation of product integrity rather than product improvement. This situation is the result of design programs run under unrealistic time schedules as consumer products are rushed to market, or of programs in which the potentials of product research efforts are underestimated. Design teams redesigning standard consumer products often are asked to work with less than sufficient information, and companies rely heavily on existing products for examples. A limited base of information leads to consumer products developed with incomplete or faulty design criteria, including criteria generated with arbitrary prioritization. Product research programs can be executed in reasonable time frames. Research can provide design teams with a product database, redirecting design efforts towards product improvement that accomodate a larger market share, or accomodate an identified market subgroup. Market advantages and increased sales can result. A methodology for formulating a product database is described.
A Test-Retest Criterion for Isometric Strength Testing
Authors: Stobbe Terrence J. , Plummer Ralph W.
Published: January 2012

Isometric strength testing has commonly been used to evaluate human strength capability. Recently it has been proposed by NIOSh as a form of administrative control for injury prevention. Historically, the number of trials used for each person-test combination has been arbitrarily selected and is often undocumented. This paper proposes a criterion for isometric testing and reports some results from using this criterion.
Case Studies in Low Back Pain
Authors: Khalil Tarek M. , Asfour S.S. , Moty E.A.
Published: January 2012

This paper examines a number of cases involving injuries resulting in low back pain.

Case history is given together with an Ergonomic evaluation profile. An aggressive low back rehabilitation program has been applied to all reported cases. The result of this rehabilitation effort related to improvement of functional abilities is given. The relationship to job environment is also discussed. The paper demonstrates the cost effectiveness considerations of low back pain rehabilitation programs with combined reference to worker's compensation laws, health care costs and productivity factors involved.
Behavioral Stereotypes and Control Design Strategies for a Six-Degree-of-Freedom “Walking” Vehicle
Authors: Beringer Dennis B. , Gruetzmacher George R. , Swanson Naomi
Published: January 2012

The problems posed by control of “walking” six-degree-of-freedom vehicles vary with specific task requirements. Different strategies are required for cruising “supervisory” control and precision foot placement. These, along with anthropometric and stereotypic considerations, directly affect the design of the manually operated controls and the degree to which multiple-axis/multiple-task integration can be achieved within a single controller. Systems that allow turn radius to be set in the absence of vehicle movement are best for planning and execution of slow close maneuvering while systems summing velocity vectors seem most advantageous for relatively high-speed cruise conditions.
Conceptual Design of A Human-Computer Interface: A Case Study in Design Methodology
Authors: Rappold Virginia A. , Sibert John L.
Published: January 2012

The purpose of this case study was to document and evaluate the application of a top-down design methodology (Foley & van Dam, 1982) to a pre-existing computer system to test the methodology's usefulness as well as to gain insights into the design process itself. System experts advocate design of a system “top-down” instead of “bottom-up” as a way to sequentially examine the complex task of interface design while allowing re-examination of previous steps in that design (Foley, 1981).

The study involved a menu-based, mini-computer system designed at Goddard Space Flight Center called the Mission Planning Terminal (MPT). The MPT will be used at Goddard for planning and scheduling of satellite activities through the NASA Network Control Center (NCC). The scheduler/analyst's task includes submitting a schedule of activities for his mission, transmitting it to NCC, and then modifying the returned schedule, if necessary, using the MPT.

The top-down design process is distinctly divided into four phases: conceptual, semantic, syntactic, and lexical (Foley, 1981). The first phase, conceptual, consists of defining key application concepts needed by the user. The semantic phases involve defining meanings such as information needed in order to use an object. The syntactic design defines sequences of inputs (similar to English grammar rules) and outputs (the two and three dimensional organization of the display). The last step, lexical design, describes how words in the input/output sequence are formed from the existing hardware input (Foley & van Dam, 1982).

The top-down methodology was applied using MPT documentation and interviews with the designers. During this process, it became clear that although a conceptual model of the MPT existed somewhere, it was never recorded. This led to numerous attempts to extract the main conceptual components of the system from the software operations documents which were constantly changed and were often incomplete. Finally, based on preliminary screen designs, state diagrams were constructed to map out components of the system. By characterization of the MPT in this way (using state diagrams), a clearer picture emerged that finally led to understanding the conceptual model. Once the conceptual model was extracted, redesign of the system, using the top-down method, quickly followed.

This case study clearly emphasizes the need for a complete and accurate conceptual model if a top-down approach is to be applied. When redesigning an existing system, it frequently becomes necessary to “extract” this model in a bottom-up manner as was the case here.
The Effectiveness of a Performance-Based Assistant in an Information Retrieval Environment
Authors: Elkerton Jay , Williges Robert C.
Published: January 2012

Assistance systems are beginning to become necessary components in human-computer systems. The present research describes an initial attempt at providing a performance-based assistant for a complicated information retrieval task. The assistant was implemented based upon an expert profile methodology. The resultant expert performance model was used to diagnose inappropriate novice search strategies. A suggestive and forceful assistant were compared against an unassisted novice subject group. The suggestive assistant highlighted appropriate search procedures for novice subjects on a keypad with a touch entry display. The forceful assistant also highlighted appropriate search procedures but eliminated inappropriate search procedures from the touch keypad. The experiment demonstrated a marked improvement in the search strategies and performance of assisted novices. These enhanced search styles were not without a cost. In this implementation, both the suggestive and forceful assistants were very intrusive on trials with advice. Consequently, further research should address the development of assistance systems that naturally transfer expertise to inexperienced users.
Study of the Errors Committed in the Use of an Online Library Catalog System
Authors: Smith Philip J. , Janosky Beverly , Hildreth Charles
Published: January 2012

The performances of thirty first-time users of an online library catalog system were studied. The subjects were asked to conduct five online searches for documents available in the library and to think out loud as they did so. An analysis of the errors made and the associated verbal protocols provided a number of insights into the underlying mental processes.
Wrist Injuries Incurred from Repetitive Motion
Authors: Wild Elizabeth , Gerberich Susan Goodwin , Coe Karen , Skovbroten Kate
Published: January 2012

Between 1978 and 1980, the number of reported wrist injuries increased from a rate of two cases per one hundred employees to sixteen cases per one hundred employees in one department of a paper products manufacturing company; costs of $158,000 were incurred by the company. These injuries included carpal tunrel syndrome and disorders including pain, numbness, tingling, aching, and weakness. In 1982, a retrospective epidemiological study was conducted to analyze this problem within the department population of forty-eight female employees classified as “flyers”. “Flying” involves sustained, repetitive movements of the upper extremities to accomplish the tasks of lifting, inspecting, and packing of flattened cartons. Data regarding relevant agent, host and environmental variables were collected by means of a self-administered questionnaire. Specific techniques ensured confidentiality and validation of information. Data analyses including a variety of statistical techniques were conducted through computer application. The mean age, height, and length of time on the job were significantly less in workers with injuries/symptoms than in those without (p<0.05). Injured workers identified more frequently the fact that large carcons and increased machine speed made a difference as to how their forearms, wrists or hands felt (p<0.05). The results of this study indicate that the younger, shorter, lees experienced worker is most susceptible to wrist injuries/problems associated with repetitive motion tasks. Applications of ergonomic principles and formal training are considered as results of these findings.
A Comparison of Blink Aided and Manual Inspection Using Laboratory and Plant Subjects
Authors: Drury Colin G. , Kleiner Brian M.
Published: January 2012

A commercially available blink comparator was compared to manual inspection of the component side of electronic circuit packs. In addition, the comparison was made using both laboratory-trained and plant-experienced inspectors. There was a considerable difference in performance as a function of circuit pack area (size) and differences in pattern between blink and manual inspection and between laboratory and plant inspectors. Overall the blink inspection device was little better than manual inspection, except for one fault type, missing components, Plant inspectors were slower than laboratory inspectors, but they found more of the most difficult faults.
Inspection Contrasting Self-Pacing and Machine Pacing
Authors: Peddada Tarakam , Bennett Corwin A.
Published: January 2012

Fifteen students worked for two hours inspecting pennies. Each subject performed under 90, 100, 110, 120, and 130% (of self-paced) and self-paced, in random order. As pacing rate increased the percentage of hits increased but the hit rate increased only1 10% while pacing increased 44%. Thus, faster pacing does increase production but at the expense of quality. Judged difficulty from 90% of self paced to 130% increased from “fairly easy” to “very hard.”
Multiple Resources and Display Formatting: The Implications of Task Integration
Authors: Wickens Christopher D. , Goettle Barry
Published: January 2012

Two experiments are reported which test the hypothesis that multiple sources of displayed information should be presented to common rather than separate resources when those sources must be integrated with a single mental model of the task. One experiment requires subjects to integrate horizontal and vertical information in a simulated air traffic control task. In support of the hypothesis performance is best when both sources are presented visually, rather than bimodally. In the control experiment when the altitude and horizontal information do not need to be integrated, performance is best when bimodal presentation is used.
Event-Related Potential Indices of Workload in a Single Task Paradigm
Authors: Horst Richard L. , Munson Robert C. , Ruchkin Daniel S.
Published: January 2012

Many previous studies of both behavioral and physiological correlates of cognitive workload have burdened subjects with a contrived secondary task in order to assess the workload of a primary task. The present study investigated event-related potential (ERP) indices of workload in a single task paradigm. Subjects monitored changing digital readouts for values that went “out-of-bounds.” The amplitude of a long-latency positivity in the ERPs elicited by readout changes increased with the number of readouts being monitored. This effect of workload on ERPs is reported, along with plans for additional analyses to address theoretical implications.
The Impact of Response Selection and Response Excution Difficulty on the Subjective Experience of Worload
Authors: Hart Sandra G. , Sellers Jerry J. , Guthart Gary
Published: January 2012

The influence of variations in response selection and response execution difficulty on the workload and performance of 11 experimental subjects was investigated. The 20 laboratory tasks they performed involved a binary response selection that required different levels of mental processing (e.g. choice reaction time, prediction, memory search, etc.). A target acquisition task was added following response selection on half of the trials. A weighted combination of bipolar ratings on nine workload-related dimensions was used to evaluate the workload experienced by the subjects. In addition, subjects rank-ordered the tasks with respect to workload before (a prediction) and again after (a retrospective comparison) performing them. Apparently minor variations in stimulus presentation resulted in significantly increased reaction times and workload ratings, as did the more obvious manipulations of response selection load. The addition of the target acquisition task increased workload ratings and reaction tines, however the “cost” of performing the two-stage task (as indicated by measures of speed, accuracy, and subjective opinion) was considerably less than would be expected by combining measures for the component tasks. Movement times for the target acquisition tasks increased significantly as a function of the index of difficulty of the target, but were not affected by the difficulty of the response selection task.
Message-Based Screen Interfaces: The Effects of Presentation Rates and Task Complexity on Operator Performance
Authors: Halstead-Nussloch Richard , Granda Richard E.
Published: January 2012

The present experiments investigated the effects of varying message-presentation rate and task complexity on human performance. Variables examined in the experiments included message rate, message presentation format, probability of a target message, and number of response alternatives for target messages. Response accuracy was used as a measure of operator performance. Significant main effects were obtained on all independent variables, except format of message flow. Increasing the message rate, target probability, and number of target categories resulted in poorer accuracy. In general, decreases in accuracy were accentuated when two or more of the manipulated factors were increased. This negative synergism must be taken into account in designing a user-system interface for control systems based on textual-message communications.
Reducing Variability in Natural-Language Interactions with Computers
Authors: Zoltan-Ford Elizabeth
Published: January 2012

The present study examined the possibility that users will model or can be shaped to the vocabulary and phrase structure of a program's output in creating their own inputs. Novice and occasional computer users interacted with four versions of an inventory program ostensibly capable of understanding natural-language inputs. The four versions differed with respect to the vocabulary and/or the phrase length presented on the subjects' CRT. One-half of the subjects were unknowingly restricted to input phrases identical to those used by their respective program, the other half were not. Additionally, one-half of the subjects communicated with the program by speaking, the other half by typing. The results indicate that recognition rates of natural-language processors will increase if users are provided with a consistently worded program output to model and then are shaped with nonthreatening error messages that reiterate those vocabulary and/or phrases that the processor can understand.
A Case Study: Comparison of an Automated Work Environment to Proposed State Laws
Authors: Palermo Susan A.
Published: January 2012

Within the past few years many studies have reported a number of problems resulting from the introduction of computers into the office environment. As a result, academia, professional groups and societies, government agencies and unions have been involved in evaluating the issues of concern. In addition, several states have proposed laws addressing the interface of the human with the VDT. Major components of these laws include:

○ Specific requirements for workstation design ○ Provision for adequate illumination ○ Provision for work/rest periods ○ Education of VDT users

This paper will detail a case study comparing existing conditions of an automated office environment with the proposed VDT laws. Included will be a review of a proposed standard and a discussion of existing ergonomic problems such as visual problems; inadequate workspace; misuse and poor design of office furniture; musculoskeletal, psychological and emotional stresses; and lack of upper management awareness. This paper will also include recommendations to improve the evaluated work environment so that it meets the requirements of the proposed law.
Interference between Pictorial Symbols and Arrows in Highway Guidance Signs
Authors: Whitaker Leslie A. , Sommer Robert
Published: January 2012

Pictorial symbols are used on highway guidance signs to indicate roadside destinations (airports, train stations, parks, rest facilities, etc.). Symbols which have strong inherent directional information (e.g., a jet air craft to designate an airport) may conflict with the sign's routing arrow itself. The directional nature of pictorial symbols was examined as a potential source of conflict with intended route information. It was predicted that disagreement between the symbol's “direction” and that of the route arrow would increase processing time. Four existing symbols were selected for examination (airport, ski trail, Amtrak station, Montreal metro). Semantic differential ratings and reaction times were measured. Results of the two methods were in substantial agreement. Only reaction time measures are reported in the present paper. When the direction of the symbol and the guidance arrow agreed, latencies to airport and Amtrak signs were significantly faster than when they disagreed. In contrast, no effect of arrow and symbol agreement was found for either the skier or the metro signs. It was concluded that some pictorial symbols (e.g., airport, Amtrak logo) suffer from inherent directionality which interferes with the rate at which route information can be processed. For symbols which can interfere with guidance information, the symbol and the route arrow should agree in their direction.
Measuring the Conspicuity of Routing Signs in Public Environments
Authors: Boersema Theo , Zwaga Harm J.G.
Published: January 2012

The conspicuity of routing signs was measured as the number of signs located in real-world scenes. Colour slides were used for stimulus presentation. A first series of experiments strongly suggested that the performance of the subjects depended on number, size, location and colour of advertisements in the environments where the routing signs were displayed. These aspects of the environments were not systematically varied, however. In a second series of experiments, advertisements systematically varying in number and size were added to a scene. The locating of routing signs deteriorated with increasing number and size of the advertisements.