Abstract
Mental rotation tasks classically involve participants deciding whether two pictures of objects, presented at different orientations, are the same or mirror images. Reaction time in these tasks increases more or less linearly with the angular difference in orientation between the two objects. This finding has led many researchers to conclude that mental rotation is performed in a manner that is (somehow) analogous to the physical rotation of the object in question. This interpretation implies, for example, that the processes underlying 90° and 180° mental rotations are qualitatively the same, differing only quantitatively. In the present study participants reported (by drawing or selection from a forced-choice array) the orientation that would result from rotating a stimulus picture 0°, 90°clockwise, 90°counterclockwise, or 180°. Analyses of participants' errors revealed qualitative differences in the distribution of error types across the different rotation conditions, suggesting that mental rotation processes may vary qualitatively and not just quantitatively as a function of rotation angle. We interpret the results by reference to specific assumptions about the form of mental orientation representations and the processes that transform these representations in mental rotation tasks.