Paul Timm

Catastrophe Models for Cognitive Workload and Fatigue in a Vigilance Dual Task

Objective: This study investigated two cusp catastrophe models for cognitive workload and fatigue for a vigilance dual task, the role of emotional intelligence and frustration in the performance dynamics, and the dynamics for individuals and teams of two participants. Background: The effects of workload, fatigue, practice, and time on a specific task can be separated with the two models and an appropriate experimental design. Group dynamics add further complications to the understanding of workload and fatigue effects for teams. Method: In this experiment, 141 undergraduates responded to target stimuli that appeared on a simulated security camera display at three rates of speed while completing a jigsaw puzzle. Participants worked alone or in pairs and completed additional measurements prior to or after the main tasks. Results: The workload cusp verified the expected effects of speed and frustration on change in performance. The fatigue cusp showed that positive and negative changes in performance were greater if more work on the secondary task was completed and whether the participants who started with the fast vigilance condition demonstrated less fatigue. Conclusion: The results supported the efficacy of the cusp models and suggested, furthermore, that training modules that varied speed of presentation could buffer the effects of fatigue. Application: The cusp models can be used to analyze virtually any cognitively demanding task set. The particular results generalize to vigilance tasks, although a wider range of conditions within vigilance tasks needs to be investigated further.

Individual differences in the experience of cognitive workload

This study investigated the roles of four psychosocial variables – anxiety, conscientiousness, emotional intelligence, and Protestant work ethic – on subjective ratings of cognitive workload as measured by the Task Load Index (TLX) and the further connections between the four variables and TLX ratings of task performance. The four variables represented aspects of an underlying construct of elasticity versus rigidity in response to workload. Participants were 141 undergraduates who performed a vigilance task under different speeded conditions while working on a jigsaw puzzle for 90 minutes. Regression analysis showed that anxiety and emotional intelligence were the two variables most proximally related to TLX ratings. TLX ratings contributed to the prediction of performance on the puzzle, but not the vigilance task. Severity error bias was evident in some of the ratings. Although working in pairs improved performance, it also resulted in higher ratings of temporal demand and perceived performance pressure.

Obstructive sleep apnea in refractory epilepsy: A pilot study investigating frequency, clinical features, and association with risk of sudden unexpected death in epilepsy

We aimed to determine the frequency of probable obstructive sleep apnea (pOSA) in refractory epilepsy monitoring unit inpatients and clinical features associated with pOSA, including risk for sudden unexpected death in epilepsy (SUDEP).

Experimental Analysis of Cusp Models

This chapter presents an empirical assessment of the cusp catastrophe models for cognitive workload and fatigue as outlined in the previous chapter. Participants were 299 undergraduates who completed a series of psychological tests and measurements, which were followed by a financial decision making task that escalated in workload. The task required the participants to work in one of three speed conditions. Results supported both cusp models for both optimizing and risk taking criteria as evidenced by a superior degree of fit compared to the alternative linear models. For workload, conscientiousness and self-control as were the elasticity-rigidity (bifurcation) factors in optimizing, and field dependence and work ethic were elasticity variables in risk tasking; speed and decision complexity were the asymmetry variables. For fatigue, work completed and work speed were the bifurcation factors, as hypothesized, for both optimizing and risk taking; field independence was the asymmetry variable for both dependent measures, and performance on an anagram test was another compensatory ability that inhibited risk taking.

The Performance-Variability Paradox: Optimizing

The study presented in this chapter examined the relationship between performance variability and actual performance of financial decision makers who were working under experimental conditions of increasing workload and fatigue. The rescaled range statistic, also known as the Hurst exponent (H) was used as an index of variability. Although H is defined as having a range between 0 and 1, 45 % of the 172 time series generated by undergraduates were negative. Participants in the study chose the optimum investment out of sets of 3–5 options that were presented a series of 350 displays. The sets of options varied in both the complexity of the options and number of options under simultaneous consideration. Depending on experimental condition, participants to make their choices within 15 s or 7.5 s. Results showed that (a) negative H was possible and not a result of psychometric error; (b) negative H was associated with negative autocorrelations in a time series. (c) H was the best predictor of performance of the variables studied; (d) three other significant predictors were scores on an anagrams test and ratings of physical demands and performance demands; (e) persistence as evidenced by the autocorrelations was associated with ratings of greater time pressure. Furthermore, persistence and overall performance were correlated, “healthy” variability only exists within a limited range, and other individual differences related to ability and resistance to stress or fatigue are also involved in the prediction of performance.