Transformation from image-based to perceptual representation of materials along the human ventral visual pathway

Every object in the world has its own surface quality that is a reflection of the material from which the object is made. We can easily identify and categorize materials (wood, metal, fabric etc.) at a glance, and this ability enables us to decide how to interact appropriately with these objects. Little is known, however, about how materials are represented in the brain, or how that representation is related to material perception or the physical properties of material surface. By combining multivoxel pattern analysis of functional magnetic resonance imaging data with perceptual and image-based physical measures of material properties, we found that the way visual information about materials is coded gradually changes from an image-based representation in early visual areas to a perceptual representation in the ventral higher-order visual areas. We suggest that meaningful information about multimodal aspects of real-world materials reside in the ventral cortex around the fusiform gyrus, where it can be utilized for categorization of materials.