Document Type




Format of Original

15 p.

Publication Date



Human Factors and Ergonomics Society

Source Publication

Human Factors

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Objective: The aim of this study was to evaluate two cusp catastrophe models for cognitive workload and fatigue. They share similar cubic polynomial structures but derive from different underlying processes and contain variables that contribute to flexibility with respect to load and the ability to compensate for fatigue.

Background: Cognitive workload and fatigue both have a negative impact on performance and have been difficult to separate. Extended time on task can produce fatigue, but it can also produce a positive effect from learning or automaticity.

Method: In this two-part experiment, 129 undergraduates performed tasks involving spelling, arithmetic, memory, and visual search.

Results: The fatigue cusp for the central memory task was supported with the quantity of work performed and performance on an episodic memory task acting as the control parameters. There was a strong linear effect, however. The load manipulations for the central task were competition with another participant for rewards, incentive conditions, and time pressure. Results supported the workload cusp in which trait anxiety and the incentive manipulation acted as the control parameters.

Conclusion: The cusps are generally better than linear models for analyzing workload and fatigue phenomena; practice effects can override fatigue. Future research should investigate multitasking and task sequencing issues, physical-cognitive task combinations, and a broader range of variables that contribute to flexibility with respect to load or compensate for fatigue.

Applications: The new experimental medium and analytic strategy can be generalized to virtually any realworld cognitively demanding tasks. The particular results are generalizable to tasks involving visual search.


Accepted version. Human Factors, Vol. 54, No. 5 (October 2012): 811-825. DOI. © 2012 Human Factors and Ergonomics Society. Used with permission.

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