Concordance between perceptual and categorical repetition effects in the ventral visual stream

The process of object categorization is an integral part of human cognition. In the present study, we have used a repetition suppression paradigm to determine the degree to which the ventral visual cortex is sensitive to categorical relationships. By using images of animals and tools, suppression across perceptual (stimulus level) and categorical repetitions (basic level and domain level) was compared and contrasted across the domain-selective and hierarchical organization of the ventral visual stream. Both perceptual and categorical repetition effects were insensitive to domain-selective tuning, with suppression most prominent in regions responding maximally to images, irrespective of stimulus domain. Likewise, both perceptual and categorical repetition produced overlapping suppression across multiple regions of the visual hierarchy. Some divergent patterns were observed. The right superior temporal sulcus demonstrated repetition suppression only at the basic level (different examples of the same basic object), and the right anterior fusiform gyrus was sensitive to direct stimulus repetition but not basic-level categorical repetition. Because of the high concordance between the response profiles of perceptual and categorical repetition effects, we conclude they arise from a common cognitive mechanism.