Neural Representations of Sensory Uncertainty and Confidence are Associated with Perceptual Curiosity

Humans are immensely curious and motivated to reduce uncertainty, but little is known about the neural mechanisms that generate curiosity. Curiosity is inversely associated with confidence, suggesting that it is triggered by states of low confidence (subjective uncertainty). The neural mechanisms of this process, however, have been little investigated. What are the mechanisms through which uncertainty about an event gives rise to curiosity about that event? Inspired by studies of sensory uncertainty, we hypothesized that visual areas provide multivariate representations of uncertainty, which are then read out by higher-order structures to generate signals of confidence and, ultimately, trigger curiosity. During fMRI, participants (17 female, 15 male) performed a new task in which they rated their confidence in identifying distorted images of animals and objects and their curiosity to see the clear image. To link sensory certainty and curiosity, we measured the activity evoked by each image in occipitotemporal cortex (OTC) and devised a new metric of "OTC Certainty" indicating the strength of evidence this activity conveys about the animal vs. object categories. We show that, consistent with findings using trivia questions, perceptual curiosity peaked at low confidence. Moreover, OTC Certainty negatively correlated with curiosity, establishing a link between curiosity and a multivariate representation of sensory uncertainty. Finally, univariate (average) activity in two frontal areas - vmPFC and ACC - correlated positively with confidence and negatively with curiosity, and the vmPFC mediated the relationship between OTC Certainty and curiosity. The results suggest that multiple mechanisms link curiosity with representations of confidence and uncertainty.