Human Factors in the Design of Tactical Display Systems for the Individual Soldier (1995) / Chapter Skim
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Appendix B: Measurement of Workload
Appendix B: Measurement of Workload
Pages 75-81
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From page 75... ...
As a result, tasks overlap, and it is difficult to provide a concrete estimate of time required since tasks performed at the same time can appear to {eke "no time." Some tasks, such as extended surveillance, require a soldier to pay attention for long periods of time without overtly doing anything. Although this represents an underioad situation, it can be stressful and, almost paradoxically, can result in cognitive overload.
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From page 76... ...
TABLE B-l Pros and Cons of Methods to Measure Workload Methods Pros Cons Primary Task High face validity Workload ox Measures assessed performance? anyway No predictivity Non-intrusive Secondary Task Good diagnosticity Intrusive Sensitive Loading task in high Poor user acceptance situations Theory-bound interpretation High face validity Dissociation with primary Subjective Response User acceptable Largely post-hoc measures Easy to obtain Tnterscale replaceability Physiological Assessment Mostly nonintrusive Subject to artifacts Objective Poor user acceptance Data rich Difficult to administer Globally diagnostic , The traditional methods by which workload has been assessed include engineering formulations, such as time-line analysis, and relatively simplistic representations, such as the time required by a task as a function of the time available.
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From page 77... ...
Secondary Task Techniques Attention and cognitive workload are intimately linked psychological constructs. With the postulation of Kahneman's concept of attentional resources, there came a paradigm shift in the area of attention that changed the perspective on attention from a filter or gate function 77
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From page 78... ...
The advantage of subjective ratings is their high face validity, which is a nontrivial factor when dealing with professional operators. However, current assessment procedures are cumbersome, and there is still disagreement about the necessity for initial baseline procedures (such as the weightings factor in the NASA Task Load Index (TEX)
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From page 79... ...
The ability to provide information on the direct status of cognitive abilities presents a formidable challenge, but one with extensive payoffs if successful. Like other psychophysiological techniques, the general form of inquiry is a search for a relationship between some measurable facet of central nervous system activity and some concomitant behavioral phenomenon.
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From page 80... ...
An important experimental question that has begun to be addressed is how context affects overlearned performance skills. The implication from laboratory research is that context is not absolutely critical.
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From page 81... ...
This is especially disturbing for those who want to use cognitive assessment of workload as a basis for design decisions or the definition of operational procedures. As technical support systems are developed, it becomes vital to address these experimental questions.
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