Abstract
We compared scene categorization in two patients with object agnosia (SB and MS) to previously published data from patient DF, who has a profound visual form agnosia. Subjects viewed three categories each of natural (beach, forest, desert) and non-natural (city, room, market) scenes. Colour is known to facilitate natural scene identification, when colour is diagnostic (Oliva & Schyns, 2000). Scene colour and spatial frequency content were manipulated to create 4 different scene versions—normally-coloured, colour-inverted, greyscale, and black & white (texture degraded). All three patients were able to categorize scenes despite object agnosia. Patient DF performed better with normally-coloured natural scenes compared to other versions of the same scenes, reflecting her spared colour and texture processing. In contrast, SB and MS, both of whom have cerebral achromatopsia, demonstrated similar performance across all versions of natural and non-natural scenes. Further, MS showed good performance for natural but was near chance for non-natural scenes, possibly due to spatial frequency content differences between these categories. DF exhibited functional activation for scenes in the parahippocampal place area (PPA) whereas both MS and SB did not, but instead showed activation in the region of the transverse occipital sulcus (TOS), an area also known to be selective for scenes. SB also showed activation in the intraparietal sulcus. These findings provide further evidence that scene categorization is independent of object recognition and suggest that activation in either regions (PPA and TOS) of the scene processing network is sufficient for scene categorization.