Goal-directed and habit-like modulations of stimulus processing during reinforcement learning

Luque, D. and Beesley, T. and Morris, R.W. and Jack, B.N. and Griffiths, O. and Whitford, T.J. and Le Pelley, M.E. (2017) Goal-directed and habit-like modulations of stimulus processing during reinforcement learning. Journal of Neuroscience, 37 (11). pp. 3009-3017. ISSN 0270-6474

Abstract

Recent research has shown that perceptual processing of stimuli previously associated with high-value rewards is automatically prioritized even when rewards are no longer available. It has been hypothesized that such reward-related modulation of stimulus salience is conceptually similar to an “attentional habit.” Recording event-related potentials in humans during a reinforcement learning task, we show strong evidence in favor of this hypothesis. Resistance to outcome devaluation (the defining feature of a habit) was shown by the stimulus-locked P1 component, reflecting activity in the extrastriate visual cortex. Analysis at longer latencies revealed a positive component (corresponding to the P3b, from 550–700 ms) sensitive to outcome devaluation. Therefore, distinct spatiotemporal patterns of brain activity were observed corresponding to habitual and goal-directed processes. These results demonstrate that reinforcement learning engages both attentional habits and goal-directed processes in parallel. Consequences for brain and computational models of reinforcement learning are discussed.