Objective: Prior research suggests that effort and reward are central to cognitive fatigue. To better understand the influence of reward on cognitive fatigue, this study examined the effect of reward type and frequency on cognitive fatigue.
Participants and methods: In an online between-subjects study, 400 participants completed a computerized switching task and were randomly sorted into one of the five possible groups based on reward condition: [1] infrequent money, [2] frequent money, [3] infrequent performance-feedback, [4] frequent performance feedback, and [5] no-reward. Cognitive fatigue was assessed using the Visual Analog Scale for Fatigue (VAS-F) during the task. Mixed effects models were used to estimate the influence of reward type and frequency on task performance and cognitive fatigue.
Results: We found that participants in the monetary groups were significantly faster (p < .001) compared to participants in the feedback and no-reward groups. We also found that participants in the frequent-money group were significantly faster than those in the infrequent-money group (p < .001). We found that the group receiving infrequent-money was associated with a decrease in VAS-F scores compared to no-reward (p = .04).
Conclusions: The current study supports the role of reward in cognitive fatigue. Our results confirm well-established findings that money positively influences on-task behavior, especially when money is provided frequently. In a cognitively healthy sample, there is some evidence to suggest that money provided infrequently could decrease feelings of fatigue. Continued work is needed to understand how, and which, specific behavioral reward manipulations reduce fatigue, especially in clinical populations most affected by fatigue.
Keywords: Cognitive fatigue; reward; reward frequency; reward type; switching.