The effect on form perception of change of orientation in the third dimension.

The experiments reported here concern the effect of change of orientation of figures in the third dimension on phenomenal shape. In one experiment, novel two-dimensional wire figures were first shown in one orientation in the sagittal plane, and recognition of them was then tested in an altered orientation in that plane. In another experiment, novel three-dimensional wire figures were first shown in one orientation, and recognition of them was tested following rotation about one of the three major axes of space. The guiding hypotheses were (a) form perception is the end result of a process of figural description; (b) orientation change that alters the perceived location of the top, bottom, and sides of a figure will affect this description; and (c) front-back reversal and rotations about the Y axis will not affect the description because front and back constitute the sides of a figure much as left and right do, and all figural sides are phenomenally equivalent. The findings support these hypotheses except for an unanticipated effect on recognition of 90 degrees rotations about the Y axis. This effect was seen as a hitherto unknown example of egocentrism in perception, since the description is governed by the retinal projection resulting from the particular vantage point of the observer.