How Effortful is Boredom? Studying Self-Control Demands Through Pupillometry (Registered Report Stage 2)

Self-control is essential for managing actions, yet its exertion is perceived as effortful. Performing a task may require effort not only because of its inherent difficulty but also due to its potential for inducing boredom, as boredom has been shown to be self-control demanding itself. So far, the extent of self-control demands during boredom and its temporal dynamics remain elusive. We employed a multimethod approach to address this knowledge gap. Ninety-five participants took part in an easy and hard version of the Stroop task. During both tasks, they indicated several times their perceived task difficulty, boredom, boredom-related effort, difficulty-related effort, overall effort, and fatigue. We tested whether pupil size, as a physiological indicator of cognitive effort, was predicted more accurately by difficulty- and boredom-related effort together than by task-difficulty-related effort alone. The best model fit included boredom-, difficulty-related effort, and their interactions with task type (easy, hard Stroop). Tonic pupil size increased during the easy Stroop, while phasic pupil size decreased with greater boredom-related effort in both tasks. Greater difficulty-related effort was linked to increases in tonic and phasic pupil size in the easy, but not in the hard Stroop. Finally, boredom-related effort in the Stroop predicted performance in a subsequent flanker task. Our results provide preliminary support that enduring boredom may not only be perceived as effortful but also be reflected in psychophysiological changes. Moreover, it may influence subsequent behavior. This underscores the importance of considering boredom as a potential confound in self-control research and broader study designs.