THE BEHAVIOURAL BASIS OF PERCEIVED SIZE AND DISTANCE.

It is suggested that perceived distance is a function of behaviour that is quantitatively adjusted to the distances of objects. This behaviour is conditioned to compound stimuli whose components include changes of stimulation due to movement. If some of the cues, and particularly those that depend on movement, are eliminated experimentally, there is a quantitative decrease in the behaviour that tends to be evoked, with a consequent shrinkage in perceived distance. This accounts for the common finding that perceived distance is a negatively accelerated increasing function of distance. Perceived size is a function of behaviour quantitatively adjusted to the dimensions of objects. If this behaviour can be evoked by objects at a distance we get size constancy. In this case the cues include those that are conditioned to distance responses, and the result is size-distance invariance. This invariance is disrupted by cue reduction. For example, elimination of distance cues dependent on motion results in increasing overestimation of size as distance increases. Two size illusions are explained in terms of the theory. (Author)
Pub. in Candian Journal of Psychology v19 n1 p1-14 1965. (Copies available only to DDC users). Abstract in French and English.