Organizational versus geometric factors in mental rotation and folding tasks.

The criteria used in performing mental rotation or mental folding tasks were studied with a paradigm that did not involve reaction times. The hypothesis was that, when perceptual-organizational factors come into conflict with the geometric features required for the correct execution of such tasks, it is the former that prevail. To verify this hypothesis two experiments were carried out. In experiment 1, subjects were asked to imagine quadrilaterals rotating round a rotation axis at different inclinations. Their responses were dependent both on the degree of tilt of the rotation axis and on the degree of tilt of the quadrilateral with respect to the rotation axis. Experiment 2 consisted of the mental execution of a folding task. In this case too, the responses depended on the degree of tilt of the folding axis and also on the complexity of the stimulus outline. In both experiments responses were divided into two groups: (i) geometrically correct responses and (ii) responses which, although incorrect, were based on perceptual-organizational criteria. In the light of the results, some theoretical implications regarding transformation operations executed by means of mental images are discussed.