Task-evoked pupillary responses track effort exertion: Evidence from task-switching

Abstract

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.

Is the juice worth the squeeze? Learning the marginal value of mental effort over time.

“…Future work could leverage physiological measures like pupillometry to elucidate both default levels and reward-induced changes in effort allocation (van der Wel & van Steenbergen, 2018). To this point, we have also found suggestive evidence that the relationship between task-evoked pupillary responses and task switch costs is stronger in low-NFC individuals (da Silva Castanheira et al, 2021).…”

Meta-control: From psychology to computational neuroscience

“…The workings of meta-control processes may also be reflected in measures of pupil dilation. In their study, Da Silva Castanheira et al (2021) examine pupil dilation as an indicator of cognitive effort during incentivized task switching (da Silva Castanheira et al, 2021). The psychophysiological results suggest that more cognitively demanding task switches are associated with larger task-evoked pupillary responses.…”

Forced choices reveal a trade-off between cognitive effort and physical pain

“…Finally, as the decision to exert cognitive effort or experience pain is highly subjective, we were interested in inter-individual differences that govern how people value and choose to avoid effort or pain. While mental effort is generally described as aversive, a given level of effort is experienced as more costly for some than for others (Cacioppo & Petty, 1982;Inzlicht, Shenhav, & Olivola, 2018), suggesting that the intrinsic value of effort influences decisions to avoid it (e.g., da Silva Castanheira, LoParco, & Otto, 2020;Sandra & Otto, 2018;Westbrook et al, 2013). Similarly, there are well documented trait differences in how individuals evaluate and respond to pain (Sullivan, Bishop, & Pivik, 1995).…”

“…While mental effort is generally described as aversive, a given level of effort is experienced as more costly for some than for others ( Cacioppo and Petty, 1982 ; Inzlicht et al, 2018 ), suggesting that the intrinsic value of effort influences decisions to avoid it (e.g. da Silva Castanheira et al, 2020 ; Sandra and Otto, 2018 ; Westbrook et al, 2013 ). Similarly, there are well documented trait differences in how individuals evaluate and respond to pain ( Sullivan et al, 1995 ).…”