Patients with category-specific visual agnosia (CSVA) often exhibit a disproportionate difficulty recognizing objects from biological categories due (in part) to the fact that exemplars from biological categories tend to be visually and conceptually more similar. Similarity is often conceived of as a pairwise property (i.e., in terms of distance in a psychological space matrix), but may be more accurately conceived of as a setwise property (i.e., in terms of shared features).