Occipitotemporal Representations Reflect Individual Differences in Conceptual Knowledge

Abstract

Through selective attention, decision-makers can learn to ignore behaviorally-irrelevant stimulus dimensions. This can improve learning and can increase the perceptual discriminability of relevant stimulus information. Across cognitive models of categorization, this is typically accomplished through the inclusion of attentional parameters, which provide information about the importance of each stimulus dimension during decision-making. These parameters are often described geometrically, such that perceptual differences over relevant psychological dimensions are accentuated (or stretched), and differences over irrelevant dimensions are down-weighted (or compressed). An open question is whether these attention parameters are reflected in the brain. We examined two published fMRI datasets in which participants learned to categorize stimuli with features that differed in their relevancy. Attentional parameters were derived for each participants using formal categorization models fit to behavioral data. Using multivoxel pattern analysis (MVPA), we found that when greater attentional weight was devoted to a particular visual feature (e.g., “color”), its value (e.g., “red”) was more easily decoded from occipitotemporal cortex. This effect was sufficiently sensitive to reflect individual differences in conceptual knowledge, indicating that occipitotemporal stimulus representations are embedded within a space similar to that formalized by classic categorization theory.