Mental Object Rotation and Egocentric Body Transformation: Two Dissociable Processes?

An important question in studies on mental rotation is whether the mental object rotation and the egocentric body transformation rely on dissociable mechanisms. We tested non-dancers and professional dancers as experts in the mental object rotation task (MORT, 3D-cubes used by Shepard & Metzler, 1971) and the mental body transformation task (MBRT, line drawings of human bodies similar to those used by Parsons, 1987). The cubes and body figures were presented in exactly the same rotation conditions; in the picture plane, 0°, 45°, 90°, 135°, and 180°, and in combination with a rotation in depth, 0° (the stimuli are rotated in the picture plane only) and 180°. We could replicate the linear increase in RT with increasing angle for the cubes whereas the RT for rotated body figures increased for not depth-rotated bodies only (back view). Though, the RTs for inverted body figures were faster when they were rotated in depth (front view) compared to when they were rotated in the picture plane only (back view). This finding suggests that participants use different strategies depending on the perceived orientation of the stimulus. The results indicate impaired performance in the MORT for the experts.