The development of binocular discrimination in infants

Abstract

The ability of 8- to 13-week-old infants to discriminate between stereoscopic and non-stereoscopic stimuli under short habituation experiences was tested repeatedly until they were 24 weeks old or able to reach for real objects with direction of gaze to one of two adjacent displays of a shadow-caster as the criterion measure. Stereopsis was demonstrated at the final session in 83% of the subjects by a reaching response to a virtual image. All but 1 of the 26 subjects discriminated on every test between depth and no-depth stimuli with no age differential; the subjects generally preferred the no-depth stimulus. While stereopsis and reactions to novelty or to complexity are possibile explanations of shadow-caster discriminations, the significant reaching response results plus the consistent gaze preference strongly support the hypothesis that binocular functioning is available at 8 weeks of age. © 1980, The Psychonomic Society, Inc.. All rights reserved.