That motion parallax could be a valuable source of distance information does not mean that our perceptual apparatus actually makes use of it. Deborah Wheeler and James Schubert recently conducted an experiment in our laboratory to investigate this matter. In a dark room, the observer viewed an array of luminous circles pasted on glass panes that were placed at differing distances. To eliminate the pictorial cue of size, the circles were drawn so that they projected images to the eye of equal size. To eliminate the pictorial cue of interposition, the circles were situated so that the observer could not see them overlap. When subjects viewed the array with one eye and their heads held still, they reported what we should predict: that all the circles were in the same plane and of equal size. When they moved their heads from side to side and could gather parallax information, some subjects still saw the circles in the same plane. For them, the movement created the impression that circles in the same plane were shifting in relation to one another. Other subjects achieved depth only between some of the circles while still others perceived the entire display correctly. Those who reported depth generally also perceived the farthest circles as larger.