The memory effect of visual perception of three-dimensional form.

The kinetic depth effect that has been discussed in a preceding paper (2) enables monocular Ss to perceive three-dimensional form as directly as do persons with serviceable binocular vision by means of retinal disparity. Yet this effect alone does not, of course, solve the entire problem of the perception of solid form. Threedimensional form is seen monocularly also when the observer does not move in relation to the object and it is also perceived in photographs and drawings. It has been mentioned in the preceding paper that an empiristic