The investigation of stimulus inversion can reveal important insights into the nature of visual object processing. Many studies have examined inversion with respect to faces, and have consistently demonstrated a large cost in the recognition of inverted compared to upright faces. Imaging studies have also demonstrated higher activation within the fusiform face area (FFA) for upright than for inverted faces. However, the inversion effect is not unique to faces, and costs of inversion on recognition are also observed for objects and scenes, although generally to a lesser extent than for faces. Here, we used functional magnetic resonance imaging (fMRI) to investigate the effect of inversion on visual processing for multiple categories of visual stimuli across multiple regions of visual cortex. Specifically, upright and inverted faces, objects, and scenes were presented to subjects, and the patterns of response within FFA, object-selective cortex (Lateral Occipital, LO), and scene-selective cortex (Parahippocampal Place Area, PPA) to each stimulus type and orientation were compared. In all high-level visual areas the patterns of response could be used to discriminate between the different categories of upright stimuli. Within the FFA, while the effect of inversion was strongest for faces, there was also an effect for non-preferred stimuli, demonstrating that face-selective cortex shows a general effect of inversion. PPA showed a strong inversion effect only for scenes, suggesting a specialization for its preferred category. In contrast the generally object-selective LO showed inversion effects for all stimulus classes. Collectively, these results demonstrate robust effects of inversion for multiple object categories in cortical visual processing and suggest that category is not the only factor contributing to the inversion effect in specialized cortical regions. Additionally, these results complement behavioral studies of inversion by demonstrating inversion effects for faces, objects, and scenes in their preferred and non-preferred regions of processing.
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