Distance perception and the ambiguity of visual stimulation: A theoretical note

Certain current views postulate that visual perception, especially of distance, is a function of optical stimulation alone. It is shown here that the optical array does not, in fact, specify absolute distance unambiguously, for either a stationary or a moving O. In view of this ambiguity of optical information, a more complex theory, comprising both visual and nonvisual information, as needed to explain, veridical perception.