Effect of differences in binocularity on perceived absolute distance.

1. Using a 0.9 x 4.0 m visual alley, perceived absolute distance was studied in four groups of subjects: binocular, cross-eyed, monocular, and induced-monocular individuals. 2. A power function between the different physical and perceived distances was adjusted and the relative and absolute errors made by the observers were calculated. Despite a tendency to overestimate distance in the monocular group, no significant differences were detected among groups. 3. The data suggest that, under natural-cue conditions, binocularity is not a determining factor for the perception of absolute distance.