Orientation priming of novel shapes in the context of viewpoint-dependent recognition.

Can visual similarity between shapes facilitate orientation priming? Five experiments are reported in which this possibility was explored by using novel two-dimensional shapes that formed homogeneous stimulus classes. After training on individual shapes in a canonical view, the recognition of these shapes was tested in several picture-plane orientations. In experiments 1 and 2 an identification task was used to replicate the classic finding obtained with the mirror-judgment task-that prior orientation cueing does not reduce the magnitude of orientation dependence in processing rotated shapes. The results of experiment 3, however, indicate that blocking trials by orientation is one condition in which orientation priming may be obtained. Experiment 4 builds on this result, and it is suggested that awareness of the blocking manipulation is not required to obtain orientation priming. In experiment 5 the mechanisms underlying this finding are explored, and evidence is offered that orientation priming is a consequence of representations that encode both shape and orientation. Such results may be considered as an extension to the 'image-based' approach to object recognition, demonstrating that generalization across exemplars may occur within recognition mechanisms that are viewpoint dependent.