Viewpoint dependency in object representation and recognition

In order to recognize an object from a certain viewpoint, it is necessary for the object's image from this viewpoint to match the object's representation in memory. Clearly, both information from this image and the object representation in memory determine recognition performance. However, the current debate on the viewpoint dependency of internal representations focuses only on the viewpoint dependency of the performance, and equates it directly with viewpoint dependency of the representation, excluding the possibility that a viewpoint-independent representation can also give rise to a viewpoint-dependent performance. In the latter case, the performance will only depend on the image information from the viewpoint, which is determined by the three-dimensional (3D) shape of the object, irrespective of how the internal representation is learnt. A recognition performance that depends on the views from which the representation is learnt will provide strong evidence against any viewpoint-independent representations. Such an implication was supported from this study with 3D natural objects. In particular, performance from views that shared the same visible major object parts was systematically different a result which is not predicted by the Recognition-By-Components theory (Biederman, Psychol. Rev. 94. 115-147, 1987).