Effect of distance information and range on two indices of visually perceived distance.

Subjects made verbal reports of the perceived distance of near visual targets and indicated their distances by pointing at them with an unseen hand. The targets were presented under three stimulus conditions: monocular, binocular, and multicue. Two ranges of target distance were studied in separate experiments: 11-39 cm and 21-33 cm. When reciprocals of both response distance and target distance were plotted, all functions were approximately linear. The verbal and manual responses (distance indices) differed greatly, but were found to be related by a constant transform. The range of target distances had no effect on either index. The standard deviation of the manual response was about half that of the verbal response. Stimulus condition had a large effect, with the multicue condition producing the greatest change in indicated distance. and the monocular condition the least. The results are discussed with reference to the definition of perceived distance, and hypothesis concerning the integration of distance information.