Explore or reset? Pupil diameter transiently increases in self-chosen switches between cognitive labor and leisure in either direction.

When people invest effort in cognitive work, they often keep an eye open for rewarding alternative activities. Previous research suggests that the norepinephrine (NE) system regulates such trade-offs between exploitation of the current task and exploration of alternative possibilities. We examined the possibility that the NE system is involved in another trade-off, i.e., the trade-off between cognitive labor and leisure. We conducted two pre-registered studies (total N = 62) in which participants freely chose to perform either a paid 2-back task (labor) versus a non-paid task (leisure), while we tracked their pupil diameter-which is an indicator of the state of the NE system. In both studies, consistent with prior work, we found (a) increases in pupil baseline and (b) decreases in pupil dilation when participants switched from labor to leisure. Unexpectedly, we found the same pattern when participants switched from leisure back to labor. Both increases in pupil baseline and decreases in pupil dilation were short-lived. Collectively, these results are more consistent with a role of norepinephrine in reorienting attention and task switching, as suggested by network reset theory, than with a role in motivation, as suggested by adaptive gain theory.