From users’ task knowledge to high‐level interface specificationSebillotte, Suzanne; Scapin, Dominique L.
doi: 10.1080/10447319409526080pmid: N/A
In the effort to define appropriate design and evaluation methods for interface usability, research work is being carried out to study the matching between users’ task characteristics and interface characteristics. This article proposes a methodology: following the task description (using Methode An‐alytique de Description; MAD), select task‐based data for defining informational constraints for the interface. The air traffic control task was described by applying MAD. Even though it was found to be suitable for capturing task‐based knowledge, the method showed the need for further refinements. This led to a more systematic way of selecting human factors rules as candidates for generic inference rules. These rules consist of premises describing specific configurations of users’ tasks (e.g., a particular informational need, a relationship between objectives, etc.) and conclusions that indicate specific requirements for the interface to conform to (e.g., a particular information display, a simultaneous access to two related functions, etc.). The air traffic control task description and the first interface specification attempts, even though they were exploratory, demonstrated the feasibility of the approach—that is, of generating interface requirements from task configurations, through human factors rules.
Winners and losers from computerization: A study of the psychosocial work conditions and health of Swedish state employeesAronsson, Gunnar; Dallner, Margareta; Åborg, Carl
doi: 10.1080/10447319409526081pmid: N/A
This study was comprised of 1,738 state‐employed visual‐display terminal (VDT) users whose work environment and health were examined through questionnaires. The aim of the study was to analyze the relationship between work organization and mental/somatic symptoms. The results showed that work conditions vary considerably, both between groups of users and between men and women. Data‐entry tasks and a combination of data‐entry and data‐acquisition tasks were more common among women. The data‐entry group reported a greater number of somatic and psychological problems and contained the greatest percentage of people spending more than 6 hours per day at a terminal. There appeared to be a critical limit of 5 to 6 hours per day beyond which the incidence of symptoms rose sharply. Recommendations for preventive measures are presented.
Performance variability as an indicator of fatigue and boredom effects in a VDT data‐entry taskPan, Christopher S.; Shell, Richard L.; Schleifer, Lawrence M.
doi: 10.1080/10447319409526082pmid: N/A
This study evaluated the utility of performance variability as an indicator of fatigue and boredom effects in a computer‐based data‐entry task. Twenty‐four data transcribers entered numeric data from tax forms at a video‐display terminal (VDT) for 3 consecutive workdays under one of the following work management conditions: Electronic Performance Monitoring (EPM) or No Electronic Performance (No EPM). Self‐ratings of fatigue and boredom were assessed at periodic intervals. The speed (keystrokes) and the accuracy (errors) of task performance were recorded on a continuous basis. Irrespective of the type of work management condition, there was an increase in fatigue and boredom from the morning to afternoon work sessions. Correspondingly, there was an increase in the variability of speed performance from the morning to afternoon work sessions for both the EPM and No EPM conditions. Trend analyses revealed a correspondence of the linear increase in fatigue and boredom with the linear increase in speed variability across the afternoon work periods under the No EPM condition. The findings of this study suggest that performance variability may be an objective indicator of fatigue and boredom effects in repetitive computer tasks.
Contours and borders in animated mimic displaysBennett, Kevin B.; Madigan, Ed
doi: 10.1080/10447319409526083pmid: N/A
Previous research has indicated that ambiguities in apparent motion (e.g., direction, rate) can result when color table techniques are used to produce animation in mimic displays. Two experiments were conducted to investigate alternative display designs in which contours (angled vs. straight) and borders (explicit vs. implicit) were varied. In Experiment 1, contours, borders, and temporal frequency interacted. At 5 Hz angled contours improved accuracy significantly. At 10 Hz explicit borders improved accuracy significantly with angled contours but degraded accuracy significantly with straight contours. In Experiment 2, the design of the angled contours was changed to convey less information and an additional border condition was added. Once again, borders and contours interacted: The widest explicit border degraded accuracy with straight contours. Angled contours also improved latency performance. The results suggest that angled contours can reduce ambiguity and improve the effectiveness of animated mimic displays by providing a redundant encoding of rate information. However, this benefit must be weighed against the associated computational costs. A secondary finding was that when contours are straight the borders should be implicit, not explicit. Alternative design solutions for animated mimic displays are also discussed.
Quantitative and qualitative differences between experts and novices in chunking computer software knowledgeYe, Nong; Salvendy, Gavriel
doi: 10.1080/10447319409526085pmid: N/A
This study investigated quantitative and qualitative differences between experts and novices in knowledge structure, specifically in their chunking of computer software knowledge. An experiment was conducted to collect pairwise relatedness ratings of 23 concepts in C computer programming from 10 experts and 10 novices. Correlation analyses of relatedness ratings were performed to examine expert‐novice differences in overall knowledge structure. The intragroup correlation coefficients of experts were greater than the intragroup correlation coefficients of novices and the intergroup correlation coefficients between experts and novices. Hence, there existed structural differences of knowledge between experts and novices. To examine how experts differ from novices quantitatively and qualitatively in their knowledge chunking, the relatedness ratings of experts were averaged within the group to give a single set of relatedness ratings, and the relatedness ratings of novices were also averaged within the group to give a single set of relatedness ratings. Then the hierarchical clustering analyses were performed on the set of relatedness ratings for the experts group and on the set of relatedness ratings for the novices group, respectively. The hierarchical clustering of C concepts made by experts and the hierarchical clustering of C concepts made by novices indicated that novices had more but smaller knowledge chunks than experts for the common set of knowledge, and thatthe rough chunking of knowledge made by novices was qualitatively similar to the rough chunking of knowledge made by experts, although on a more detailed level qualitative differences still existed.