The effect of fatigue on performance in complex visuo-cognitive tasks

Abstract

Sleep disruption literature has largely focused on exploring sleep disruptions effects on relatively simple tasks with less attention given to how it impacts more complex tasks. Further, research has given very little attention on how performance fairs when participants also have to switch between tasks, in both a voluntary and forced state. The goal of this thesis was, therefore, to expand on previous investigations of sleep loss and its effects on performance of complex visuo-cognitive tasks whilst either voluntarily or forcibly task switching. Over the course of four experiments this was examined. Experiment 1 and 2 explored the effects of both sleep restriction and sleep deprivation and the cost they have on voluntary task switching performance. These experiments revealed that individuals can largely compensate for the negative effects of sleep restriction especially when they spend longer preparing for an upcoming switch in tasks. However, when they have experienced sleep deprivation these effects become more severe, causing fewer words to be generated and an increase in the number of switches made. Experiment 3, explored how the removal of control over the task in terms of forcing them when to switch, impacted performance between sleep conditions, while also seeing how it compares to voluntary switching. Results highlighted that once control of the task was removed a larger profile of errors emerged.

Specifically, with the reduction in the number of words in both the sleep deprived condition and the forced switching condition, as well as, sleep deprived participants having a longer resumption lag. Finally, Experiment 4 addressed two key components. The first component addressed the sensitivity of subjective measures of sleepiness versus objective measures of sleepiness. Results highlighted that subjective measures of sleepiness are more sensitive to the feelings of fatigue and are resilient against individual differences unlike the objective measures. The second component aimed to address the differences between voluntary versus forced switching and sleep deprived versus Control while switching between two tasks that contained two different types of cognitive task goals. Issues arose during data collection that hindered collection of a full dataset and subsequently no firm conclusions can be drawn. Based on the results from these experiments, this thesis demonstrates that the negative effects of sleep loss are dependent on the task constraints and the amount of sleep lost. However, it is clear the harder the task becomes the more difficult it is for individuals to compensate for the negative effects of fatigue when performing complex visuo-cognitive tasks. The implication of this research is that both fatigue and task switching are an important consideration when managing small daily tasks whilst also addressing the potential impact it poses on safety concerns in many industries.

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Identifiers

ORCID for Matthew Garner: orcid.org/0000-0001-9481-2226

ORCID for Dominic Taunton: orcid.org/0000-0002-6865-089X

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