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

Self-control is essential for managing our 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 by 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 current sensation of task difficulty, boredom, boredom-related cognitive effort, difficulty-related cognitive effort, overall effort, and fatigue. We tested if pupil size, as a physiological indicator for cognitive effort, was predicted more accurately by overall cognitive effort (difficulty- and boredom-related) than by task-difficulty-related cognitive effort alone. The best model fit was found for a model including boredom- and difficulty-related effort as well as 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 task predicted task performance in a subsequent flanker task. Our results highlight, that enduring boredom is not only perceived as effortful but also reflects in psychophysiological changes. Moreover, it has behavioral relevance.