Visual perceptual processing under cognitive fatigue: An inspection time study


Cognitive fatigue (CF) can result from sustained mental effort and is characterized by subjective feelings of exhaustion and impaired cognitive performance. CF has also been shown to result in slowed simple reaction time (RT); however, it is unknown what stage of motor processing (perception, preparation, or response initiation) underlies this effect. While previous work indicates that motor preparation declines do not explain this phenomenon, this study examines whether perceptual processing impairments are a more likely explanation for slowed simple RT in CF. Perceptual processing was assessed using visual inspection time (IT) task, which measures the duration of exposure to a visual stimulus at which participants reliably identify the stimulus at threshold accuracy (e.g., 80% correct). It was predicted that if impaired perceptual processing underlies CF-associated RT increases, then IT decrements would also be observed following a cognitively fatiguing task. On separate days, participants (n=5) completed a 1h control (documentary film) and cognitive (math & memory) task. Pre- and post-tests conducted in conjunction with each task included a subjective fatigue questionnaire, a simple visual RT task, and an IT task. A significant increase in subjective CF (p=0.015) was found from pre- to post-test in only the cognitive task, suggesting successful inducement of CF. However, simple RT appeared to be unchanged, and inspection time at threshold did not increase. Although further investigation is required, these results do not support an impact of CF on RT, nor the hypothesis that any CF-associated RT increases are attributable to impaired stimulus perception.

Acknowledgments: Supported by NSERC