Differential effects of object orientation on imaginary object/viewer transformations.

Given a specific view of a simple symmetrical object, participants were asked whether a certain imaginary transformation could result in a second viewed image. An experiment was conducted in which the participants had either to mentally rotate an object or to imagine themselves looking at the object from another position (i.e., the object-based condition and the viewer-based condition, respectively). In the experiment, combinations of these imagery tasks (i.e., the combined conditions) were also included. The symmetrical objects could be oriented horizontally or vertically. The performance in the object-based conditions was generally equal to or better than the performance in the viewer-based conditions. In addition, there were more confusions for shapes with a horizontal orientation, especially when viewer-based upside-down rotations were involved, with an apparent mediating role of object rotation in the combined conditions.