Inability to reason about an object's orientation using an axis and angle of rotation.

The kinematic bases by which humans imagine an object turn from one orientation to another are unknown. The studies reported here show that individuals of high spatial ability are, in most cases, unable to imagine a Shepard-Metzler object rotate about an axis and angle so as to accurately envision its appearance. Nor can they conceive of the axis and angle by which it would rotate in a shortest path between two orientations. Accuracy progressively improves across cases in which neither angle, one of the angles, or both angles between the rotation axis and viewer-environment frame and between the axis and object limb are canonical. When canonical, the angles are more accurately observed from one viewpoint to hold constant in rotation. Such inability, with rare exceptions, is probably true for other kinematic operations requiring fine control of multiple spatial relations. Objects' orientations are not readily represented in terms of shortest path axis and angle.