1Mental spatial transformations of objects and perspective

This study sought evidence for the independence of two classes of mental spatial transformation: object-based spatial transformations and egocentric perspective transformations. Two tasks were designed to selectively elicit these two transformations using the same materials, participants, and task parameters: one required same-different judgments about pairs of pictures, while the other required left-right judgments about single pictures. For pictures of human bodies, the two tasks showed strikingly different patterns of response time as a function of stimulus orientation. Moreover, across individuals, the two tasks had different relationships to psychometric tests of spatial ability. The chronometric and individual difference data converge with neuropsychological and neuroimaging data in suggesting that different mental spatial transformations are performed by dissociable neural systems. Please address correspondence concerning this article to Jeffrey M. Zacks, Department of Psychology, Washington University, Saint Louis, MO 63130. Electronic mail may be sent to jzacks@artsci.wustl.edu. We would like to thank John Gabrieli for his technical assistance and thoughtful advice, Mary Hegarty for providing the Perspective-taking test and helpful discussion, and Asher Koriat, Janice Murray, Joel Norman, and Beverly Roskos-Ewoldson for insightful comments on previous drafts. This research was supported in part by a Stanford University Humanities & Sciences Dissertation Fellowship to the first author, and by an NRSA post-doctoral fellowship to the fourth author