Abstract
Cognitive fatigue is a known factor in errors and major accidents. What is unknown is the impact that cognitive fatigue might have on the subjective assessment of usability. If users are regularly cognitively depleted when using a given system, and fatigue makes a difference in their usability assessment, then a true measure of usability would be derived only by testing users in that fatigued state. In this study, forty-three participants voted using twelve prototype paper voting ballots. Half of the ballots were classified as being of low usability and the other half as having high usability. These ballots were randomly assigned and participants completed six ballots before a fatigue manipulation and six after the manipulation. Each ballot was rated by the user with the System Usability Scale (SUS), and pre- and post-fatigue means were compared. No significant main effect was found for fatigue and no interaction was present, although the data suggest the effect may have been masked due to the high variance in the usability of the systems assessed.
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