Number of co-authors:11
Number of publications with 3 favourite co-authors:Joel S. Warm:7Peter A. Hancock:4Jonathan P. Gluckman:3
William N. Dember's 3 most productive colleagues in number of publications:Joel S. Warm:17Peter A. Hancock:14Jonathan P. Gluckm..:4
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William N. Dember
Publications by William N. Dember (bibliography)
Grubb, Paula L., Warm, Joel S., Dember, William N. and Berch, Daniel B. (1995): Effects of Multiple-Signal Discrimination on Vigilance Performance and Perceived Workload. In: Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting 1995. pp. 1360-1364.
Prior vigilance studies have shown that successive monitoring tasks involving absolute judgments are more capacity-demanding than simultaneous tasks which are comparative in nature. Most of these data stem from experiments utilizing simple discriminations and single-target displays, and, consequently, little is know regarding performance on sustained attention tasks with more complex displays. Observers in the present study monitored either one (0-bits display uncertainty), two (1-bit display uncertainty), or four (2-bits display uncertainty) indicators on a simulated aircraft display for the occurrence of critical signals presented in either a simultaneous or a successive format. Results indicated that correct detections declined as display uncertainty increased, and that this effect was more pronounced in the simultaneous format. Moreover, workload scores increased with display uncertainty, particularly in the simultaneous condition. These findings suggest that in more complex monitoring situations in which there is a scanning imperative successive tasks may have an advantage over their simultaneous counterparts.
© All rights reserved Grubb et al. and/or Human Factors Society
Moroney, Brian W., Warm, Joel S. and Dember, William N. (1995): Effects of Demand Transitions on Vigilance Performance and Perceived Workload. In: Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting 1995. pp. 1375-1379.
This study examined the effects of transitions in task demand on vigilance performance and perceived mental workload. Task demand was manipulated through variations in background event rate -- the rate of cascade of neutral events which must be monitored in order to detect critical signals. As is typical in vigilance research, overall performance varied inversely with event rate in all phases of the study. The post-transition performance of observers shifted from a fast-to-slow event rate (high-to-low task demand) remained below that of their continuous slow event rate controls, and was thus unaffected by the shift. In contrast, the post-transition performance of monitors shifted in the opposite direction, slow-to-fast event rate, was affected by the shift. In this case, the performance of the shifted observers fell below that of their continuous fast event rate controls. These results challenge prior findings indicating that psychophysical contrast is the representative outcome of shifts in information-processing demand in vigilance tasks (Krulewitz, Warm,&Wohl, 1975). Consistent with previous findings, workload scores, as indexed by the NASA-TLX, fell at the mid-to-upper level of the scale. Shifted observers who experienced both high and low levels of task demand during the vigil showed differences in composite ratings on the Mental Demand subscale. These results serve to caution that workload measurements obtained through the NASA-TLX at the end of an experimental session containing variations in task demand do not simply reflect an averaging of the observer's demand experiences.
© All rights reserved Moroney et al. and/or Human Factors Society
Dember, William N., Warm, Joel S., Nelson, W. Todd, Simons, Karen G., Hancock, Peter A. and Gluckman, Jonathan P. (1993): The Rate of Gain of Perceived Workload in Sustained Attention. In: Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting 1993. pp. 1388-1392.
Perceived workload was measured via the NASA TLX following a visual vigilance task. Five task durations (10, 20, 30, 40, or 50 min) were combined pictorially with two levels of discrimination difficulty (easy, hard) in a between groups design. Detection probability, computed from the final 10 min of watch in each duration condition, varied inversely with signal salience and declined over time. Overall workload varied directly with salience and increased linearly over time. The temporal growth in perceived workload was independent of signal salience. This result suggests that the rate of gain in workload is based upon general features of the vigilance situation rather than specific psychophysical demands such as signal salience.
© All rights reserved Dember et al. and/or Human Factors Society
Becker, Ami B., Warm, Joel S., Dember, William N., Sparnall, JoAnn, DeRonde, Laura and Hancock, Peter A. (1992): Effects of Aircraft Noise on Vigilance Performance and Perceived Workload. In: Proceedings of the Human Factors Society 36th Annual Meeting 1992. pp. 1513-1517.
This study examined the effects of exposure to intermittent jet aircraft noise played through stereophonic speakers (70dBA or 95dBA maximum intensity) on performance efficiency and perceived workload in a 40-min visual vigilance task. The noise featured a Doppler-like quality in which planes seemed to approach from the monitor's left and recede to the right. Performance in noise, measured in terms of perceptual sensitivity (d'), was significantly poorer than in a quiet condition. Moreover, in comparison to subjects performing in quiet, those who operated in noise were less able to profit from knowledge of results (KR) regarding performance efficiency. In addition to its negative effects upon signal detectability, noise significantly elevated perceived workload, as indexed by the NASA-TLX. This effect was robust; it was not mitigated by KR, even though KR served generally to reduce the overall level of perceived workload in the study. The consistency of the effects of noise in regard to both performance efficiency and perceived workload challenges a recent conclusion offered by Koelega and Brinkman (1986) that lawful relations are not observable in studies of the effects of noise on vigilant behavior.
© All rights reserved Becker et al. and/or Human Factors Society
Warm, Joel S., Dember, William N., Gluckman, Jonathan P. and Hancock, Peter A. (1991): Vigilance and Workload. In: Proceedings of the Human Factors Society 35th Annual Meeting 1991. pp. 980-981.
Becker, Ami B., Warm, Joel S., Dember, William N. and Hancock, Peter A. (1991): Effects of Feedback on Perceived Workload in Vigilance Performance. In: Proceedings of the Human Factors Society 35th Annual Meeting 1991. pp. 1491-1494.
Gluckman, Jonathan P., Dember, William N. and Warm, Joel S. (1988): Capacity Demand in Dual-Task Monitoring of Simultaneous and Successive Vigilance Tasks. In: Proceedings of the Human Factors Society 32nd Annual Meeting 1988. pp. 1463-1465.
Parasuraman and Davies (1977) have proposed a taxonomic analysis of vigilance performance which emphasizes the types of discriminations observers are required to make and the information-processing demands placed upon them. According to Parasuraman and Davies, successive (absolute judgement) tasks are more capacity-demanding than simultaneous (comparative judgement) tasks because they invoke working memory. This idea has received support from several investigations demonstrating that psychophysical factors which degrade vigilance performance have more of a negative impact upon successive than upon simultaneous tasks (see Parasuraman, Warm and Dember, 1987 for review). The present study examined the capacity-demand notion further by determining the effects that the two types of tasks have upon one another when they are both performed in a common vigilance session. By doing so, it provides the initial experimental effort to investigate the task dimension of the taxonomy within the context of a previously unexplored aspect of Parasuraman and Davies' classification system, source complexity.
© All rights reserved Gluckman et al. and/or Human Factors Society
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