Adverse effects following acute stress are traditionally thought to reflect functional impairments of central executive-dependent cognitive-control processes. However, recent evidence demonstrates that cognitive-control application is perceived as effortful and aversive, indicating that stress-related decrements in cognitive performance could denote decreased motivation to expend effort instead. To investigate this hypothesis, we tested 40 young, healthy individuals (20 female, 20 male) under both stress and control conditions in a 2-day study that had a within-subjects design. Cognitive-effort avoidance was assessed using the demand-selection task, in which participants chose between performing low-demand and high-demand variants of a task-switching paradigm. We found that acute stress indeed increased participants’ preference for less demanding behavior, whereas task-switching performance remained intact. Additional Bayesian and multiverse analyses confirmed the robustness of this effect. Our findings provide novel insights into how stressful experiences shape behavior by modulating our motivation to employ cognitive control.

A spate of research has examined how individuals regulate effortful processing in service of goal-directed behaviors. One key challenge in developing an account of this regulation is quantifying the momentary amount of cognitive effort exerted by an individual in service of their goals. A growing body of literature has suggested using task-evoked pupil dilations as a potential psychophysiological index of cognitive effort; however, it remains unclear whether pupil diameter indexes effort exertion or merely reflects task load, as both are tightly intertwined. Here, we attempt to disentangle these disparate accounts of pupil diameter by leveraging individual differences in executive function (as measured by Stroop interference) and a motivational manipulation (i.e., monetary incentives) while participants complete a task-switching paradigm. In line with both the effort and demand accounts, we observed larger task-evoked pupillary responses (TEPRs) for trials in which there was a task switch versus a task repetition. Additionally, we found that larger phasic pupillary responses at baseline (without reward incentives) predicted smaller switch costs. Mirroring this pattern, individual differences in reward-induced switch cost reductions were predicted by reward-induced increases in phasic pupil diameter. Finally, we observed that the interrelationship between effort and pupil diameter at baseline was modulated by individual differences in Stroop interference costs. Together, these findings provide support for an effort account of TEPRs, and suggest that pupillometry is a viable index of cognitive effort.

Recent work has highlighted neural mechanisms underlying cognitive effort-related discounting of anticipated rewards. However, findings on whether effort exertion alters the subjective value of obtained rewards are inconsistent. Here, we provide a more nuanced account of how cognitive effort affects subsequent reward processing in a novel task designed to assess effort-induced modulations of the Reward Positivity, an event-related potential indexing reward-related neural activity. We found that neural responses to both gains and losses were significantly elevated in trials requiring more versus less cognitive effort. Moreover, time–frequency analysis revealed that these effects were mirrored in gain-related delta, but not in loss-related theta band activity, suggesting that people ascribed more value to high-effort outcomes. In addition, we also explored whether individual differences in behavioral effort discounting rates and reward sensitivity in the absence of effort may affect the relationship between effort exertion and subsequent reward processing. Together, our findings provide evidence that cognitive effort exertion can increase the subjective value of subsequent outcomes and that this effect may primarily rely on modulations of delta band activity.

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Engaging in demanding mental activities requires the allocation of cognitive control, which can be effortful and aversive. Individuals thus tend to avoid exerting cognitive effort if less demanding behavioral options are available. Recent accounts propose a key role for dopamine in motivating behavior by increasing the sensitivity to rewards associated with effort exertion. Whether dopamine additionally plays a specific role in modulating the sensitivity to the costs of cognitive effort, even in the absence of any incentives, is much less clear. To address this question, we assessed cognitive effort avoidance in patients (n = 38) with Parkinson’s disease, a condition characterized by loss of midbrain dopaminergic neurons, both ON and OFF dopaminergic medication and compared them to healthy controls (n = 24). Effort avoidance was assessed using the Demand Selection Task (DST), in which participants could freely choose between performing a high-demand or a low-demand version of a task-switching paradigm. Critically, participants were not offered any incentives to choose the more effortful option, nor for good performance. Healthy controls and patients OFF their dopaminergic medications preferred the low-demand option, in keeping with the tendency to avoid effort on this task previously demonstrated in young adults. In contrast, patients ON dopaminergic medications displayed significantly less effort avoidance than when they were OFF medications. This change in preference could not be explained by differences in task-switching performance or the patients’ ability to detect the different levels of cognitive demand in the DST. Our findings provide evidence that dopamine replacement in Parkinson’s patients increases the willingness to engage in cognitively demanding behavior, even in the absence of any clear benefits. These results suggest that dopamine plays a role in reducing the sensitivity to effort costs that is independent of its role in enhancing the sensitivity to the benefits of effort exertion.