And yet They Tire: Cognitive Fatigue Facilitates Task Disengagement and Worsens Performance

The negative effect of prior task engagement on self-control performance is a salient human experience. Yet, earlier studies pointed to inconsistent effects of prior demands on task performance. The current, pre-registered laboratory study (N = 321) applied the psychobiological model of endurance to test the motivational consequences of fatigue on self-control through inhibited task persistence. We advanced shortcomings in prior dual-task designs by (1) using an adaptive and long (1 hour) fatigue induction and (2) adding the option to actively disengage from the main task, allowing persistence to influence performance. Findings illustrated that participants who completed the fatigue induction protocol showed large post-induction differences in subjective fatigue and shorter persistence, as well as lower performance. Exploratory mediations indicated that the effect of prior task engagement on subsequent persistence and performance was fully mediated by subjective fatigue. As suggested by recent theorization and empirical efforts, the present study supports the transition of self-control research towards perceived fatigue.