Proceedings of the Annual Meeting of the Cognitive Science Society

We explore the interaction between local-global informa- tion processing in visual perception, leveraging a visual phenomenon known as crowding, whereby the perception of a target stimulus is impaired by the presence of nearby ankers. The majority of established models explain the crowding e?ect in terms of local interactions. How- ever, recent experimental results indicate that a classical crowding e?ect, the deterioration in the discrimination of a vernier stimulus embedded in a square, is alleviated by the presence of additional anker squares (\uncrowd- ing"). Here, we propose that crowding and uncrowding arise from cortical inferences about hierarchically orga- nized groups, and formalize this concept using a hierarchi- cal Bayesian model. We show that the model reproduces both crowding and uncrowding for anked vernier discrim- ination. More generally, the model provides a normative explanation of how visual information might simultane- ously ow bottom-up, top-down, and laterally, to allow the visual system to interactively process local and global features in the visual scene.