OBJECT RECOGNITION WITHOUT KNOWLEDGE OF OBJECT ORIENTATION

Several theories have been proposed to explain our ability to recognis e objects from a number of viewpoints. Orientation-dependent accounts emphasize the position of the object relative to the viewer, while ori entation-independent accounts (e.g. Marr) rely on descriptions of an o bject's component parts relative to its principal axis of elongation. An opportunity to compare the merit of these theories has arisen in a patient (L.G.) who had a rare neuropsychological sigh in which knowled ge of the canonical upright of object drawings was profoundly disrupte d. Such orientation errors were evident in her drawings from memory an d to copy, and in an orientation-matching task. In a critical experime nt she showed a deficit in providing the canonical upright of individu al object drawings that was independent of any difficulty in object re cognition. The implications of these data for theories of object recog nition are discussed.