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.

The performance-variability paradox, financial decision making, and the curious case of negative Hurst exponents.

This study 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 to 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. One experimental condition required participants to make their choices within 15 sec, and the other condition required them to choose within 7.5 sec. 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. It was concluded, furthermore, that persistence and overall performance were correlated, that '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.

The minimum entropy principle and task performance.

According to the minimum entropy principle, efficient cognitive performance is produced with a neurocognitive strategy that involves a minimum of degrees of freedom. Although high performance is often regarded as consistent performance as well, some variability in performance still remains which allows the person to adapt to changing goal conditions or fatigue. The present study investigated the connection between performance, entropy in performance, and four task-switching strategies. Fifty-one undergraduates performed 7 different computer-based cognitive tasks producing sets of 49 responses under instructional conditions requiring task quotas or no quotas. The temporal patterns of performance were analyzed using orbital decomposition to extract pattern types and lengths, which were then compared with regard to Shannon entropy, topological entropy, and overall performance. Task switching strategies from a previous study were available for the same participants as well. Results indicated that both topological entropy and Shannon entropy were negatively correlated with performance. Some task-switching strategies produced lower entropy in performance than others. Stepwise regression showed that the top three predictors of performance were Shannon entropy and arithmetic and spatial abilities. Additional implications for the prediction of work performance with cognitive ability measurements and the applicability of the minimum entropy principle to multidimensional performance criteria and team work are discussed.

Cusp catastrophe models for cognitive workload and fatigue: a comparison of seven task types.

The study introduces a nonlinear paradigm that addresses several unresolved problems concerning cognitive workload and fatigue: (a) how to separate the effects of workload versus fatigue, (b) whether the upper boundaries of cognitive channel capacity are fixed or variable, and how multitasking produces a bottleneck phenomenon, (c) that prolonged time on task can produce performance decrements but also produce improvements in task performance associated with practice and automaticity, and that (d) task switching can alleviate fatigue but could be mentally costly. This study describes two cusp catastrophe models that have become useful for separating the workload and fatigue performance phenomena and explores the role of task switching and multitasking in both performance phenomena. In the experiment, 105 undergraduates completed seven computer-based tasks seven times under one of four experimental conditions: tasks fully alternated, tasks aggregated with the multitask module performed first, aggregated with the multitask module performed last, and where the participants chose the task order themselves. Results supported both the cusp models such that fatigue effects were stronger for tasks with higher memory or attentional demand, and were often counteracted by practice effects; spelling ability acted as a compensation variable in most cases, and the intervening amount of work done acted as the bifurcation variable. For cognitive workload, catastrophic shifts in performance were noted between the single tasks and the multitask, with relative difficulty of the single task acting as the load (asymmetry) variable and the flexible task ordering condition as the bifurcation variable.

Cusp catastrophe models for cognitive workload and fatigue in a verbally cued pictorial memory task.

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 real-world cognitively demanding tasks. The particular results are generalizable to tasks involving visual search.

New paradigm for task switching strategies while performing multiple tasks: entropy and symbolic dynamics analysis of voluntary patterns.

It has become well established in laboratory experiments that switching tasks, perhaps due to interruptions at work, incur costs in response time to complete the next task. Conditions are also known that exaggerate or lessen the switching costs. Although switching costs can contribute to fatigue, task switching can also be an adaptive response to fatigue. The present study introduces a new research paradigm for studying the emergence of voluntary task switching regimes, self-organizing processes therein, and the possibly conflicting roles of switching costs and minimum entropy. Fifty-four undergraduates performed 7 different computer-based cognitive tasks producing sets of 49 responses under instructional conditions requiring task quotas or no quotas. The sequences of task choices were analyzed using orbital decomposition to extract pattern types and lengths, which were then classified and compared with regard to Shannon entropy, topological entropy, number of task switches involved, and overall performance. Results indicated that similar but different patterns were generated under the two instructional conditions, and better performance was associated with lower topological entropy. Both entropy metrics were associated with the amount of voluntary task switching. Future research should explore conditions affecting the trade-off between switching costs and entropy, levels of automaticity between task elements, and the role of voluntary switching regimes on fatigue.