Canonical views in object representation and recognition.

Human performance in the recognition of 3-D objects, as measured by response times and error rates, frequently depends on the orientation of the object with respect to the observer. We investigated the dependence of response time (RT) and error rate (ER) on stimulus orientation for a class of random wire-like objects. First, we found no evidence for universally valid canonical views: the best view according to one subject's data was often hardly recognized by other subjects. Second, a subject by subject analysis showed that the RT/ER scores were not linearly dependent on the shortest angular distance in 3D to the best view, as predicted by the mental rotation theories of recognition. Rather, the performance was significantly correlated with an image-plane feature by feature deformation distance between the presented view and the best (shortest-RT and lowest-ER) view. Our results suggest that measurement of image-plane similarity to a few (subject-specific) feature patterns is a better model than mental rotation for the mechanism used by the human visual system to recognize objects across changes in their 3-D orientation.