Is the anisotropy of perceived 3-D shape invariant across scale?

A number of studies have resulted in the finding of a 3-D perceptual anisot ropy, whereby spatial intervals oriented in depth are perceived to be small er than physically equal intervals in the frontoparallel plane. In this exp eriment, we examined whether this anisotropy is scale invariant. The stimul i were L shapes created by two rods placed flat on a level grassy field, wi th one rod defining a frontoparallel interval, and the other, a depth inter val. Observers monocularly and binocularly viewed L shapes at two scales su ch that they were projectively equivalent under monocular viewing. Observer s judged the aspect ratio (depth/width) of each shape. Judged aspect ratio indicated a perceptual anisotropy that was invariant with scale for monocul ar viewing, but not for binocular viewing, When perspective is kept constan t, monocular viewing results in perceptual anisotropy that is invariant acr oss these two scales and presumably across still larger scales. This scale invariance indicates that the perception of shape under these conditions is determined independently of the perception of size.