Metzler and Shepard advanced the opinion that the internal representation of such an object shares properties of the object itself and of its two-dimensional perspective representation. It resembles the perspective view in its incorporation of information concerning the orientation of the object in relation to the viewer. It resembles the object in that “cognitive operations upon the representation are more simply related to properties specifiable in three-dimensional space than to properties peculiar to the particular two-dimensional projection”.For example, imagined alterations in orientation can be related clearly to the object and its properties,but only with difficulty,if at all, to the two-dimensional perspective drawing.