Abstract
This study investigated the impact of repeated sessions of a sustained visual search task (SVS) on participant fatigue, a critical factor in workplace safety and accident prevention (Matthews et al., 2019). Across four sessions, we measured fatigue using subjective (self-reported – NASA TLX and Rating of Fatigue Scale [RoF]) and objective performance and physiological metrics (e.g., response time, error rate, heart rate, blood pressure, near point convergence) in 13 participants.
Each session involved a fifteen-minute task simulating the cognitive demands of vessel navigation. Total testing time lasted 90 minutes. Fatigue was assessed before the first session and after each subsequent session to monitor changes over time.
Our findings demonstrated significant increases in subjective fatigue scores (NASA TLX, RoF, both p < .001), mixed findings with the physiological measures (no change in blood pressure or heart rate, significant increase in near point convergence p < .001). Contrary to expectations, performance measures of response times and error rates did not deteriorate; in fact, response times improved significantly in sustained attention tasks (SART, p < .001; SVS, p < .01), suggesting potential learning effects.These learning effects may have masked any cognitive fatigue effects on performance, and delineating the relationship between changes in performance due to learning and fatigue will be the focus of future studies.
This research contributes to our understanding of the complexity of cognitive fatigue with the goal of enhancing safety and highlights the challenges in measuring multifaceted constructs like cognitive fatigue.
