PT  - JOURNAL ARTICLE
AU  - Joanne C. Van Slooten
AU  - Sara Jahfari
AU  - Tomas Knapen
AU  - Jan Theeuwes
TI  - Pupil responses as indicators of value-based decision-making
AID  - 10.1101/302166
DP  - 2018 Jan 01
TA  - bioRxiv
PG  - 302166
4099  - http://biorxiv.org/content/early/2018/04/16/302166.short
4100  - http://biorxiv.org/content/early/2018/04/16/302166.full
AB  - Pupil responses have been used to track cognitive processes during decision-making. Studies have shown that in these cases the pupil reflects the joint activation of many cortical and subcortical brain regions, also those traditionally implicated in value-based learning. However, how the pupil tracks value-based decisions and reinforcement learning is unknown. We combined a reinforcement learning task with a computational model to study pupil responses during value-based decisions, and decision evaluations. We found that the pupil closely tracks reinforcement learning both across trials and participants. Prior to choice, the pupil dilated as a function of trial-by-trial fluctuations in value beliefs. After feedback, early dilation scaled with value uncertainty, whereas later constriction scaled with reward prediction errors. Our computational approach systematically implicates the pupil in value-based decisions, and the subsequent processing of violated value beliefs, ttese dissociable influences provide an exciting possibility to non-invasively study ongoing reinforcement learning in the pupil.