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Abstract

The human lateral occipital complex (LOC) has been implicated in object recognition, but it is unknown whether this region represents low-level contours or more abstract descriptions of object shape. We tested this question using event-related fMRI adaptation in which lower neural responses are observed for two identical than two different consecutively-presented stimuli (Kourtzi Kanwisher, 2000). Adaptation across a change between the two stimuli implicates a common neural representation invariant to that change. We found adaptation in the LOC when perceived shape was identical but contours differed because occluding bars occurred in front of the shape in one stimulus and behind the shape in the other. However, in a second experiment we found no adaptation when contours were identical but perceived shapes differed because of a figure-ground reversal. Further studies showed adaptation across small rotations of objects either in the frontal plane or in depth, but not across mirror-image reversals or changes in the 3D configuration of objects. These results indicate that the LOC represents not simple image features but higher-level shape information.