Abstract: The relationship between convergence and distance judgment, with interocular distance as a variable, was experimentally studied. 32 persons with interocular distances ranging from 56 mm to 70mm served as observers. Two conditions were used: (1) Convergence was controlled by means of polaroids, so as to produce a fuscd image artificially at different distances, while the physical distance of the stimuli remained constant; (2) Convergence varied in a natural manner with the physical distances of the stimuli.The results showed:(1) Convergence plays an important role in distance perception. In condition I) distance judgtnents fall very near to the calculated values of the convergence distances. In condition 2) distance can be perceived quite accurately by using convergence cues within a certain distance range.(2) Under our experimental conditions, convergence serves as a cue for distance as far as 35—45 metres, which is much greater than the commonly held opinion of 20 metres.(3) Observers with different interocular distances showed difference in the accuracy of distance judgments. The greater the interocular distance the more accurate is the judgment of distance.

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