Categorical relations in shape perception.

Many researchers have proposed that objects are perceived as structural descriptions, which specify the configuration of an object's features (or parts) in terms of their categorical relations to one another. Others have proposed that objects are perceived as views, which specify the configuration of an object's features in terms of their coordinates, in particular 2D views. This paper presents five experiments testing these competing accounts of the perception of the configuration of an object's features. Subjects learned to recognize a set of target objects and were tested for their ability to distinguish them from various distractors that differed either in their categorical relations or their coordinates. Subjects were consistently more likely to confuse both 2D and 3D objects that were similar in their parts' relations to each other than to confuse objects similar in their parts' coordinates (in any reference frame). This effect persisted when subjects were allowed to view the objects as long as they wished and when they were explicitly trained to distinguish them from the distractors. These findings suggest that we perceive an object's features in terms of their categorical relations to one another. A preliminary model of the findings is presented.