Purchase this article with an account.
A.M. Brown, J.A. Miracle, D.T. Lindsey; Infant Stereopsis Development: Limitations on the Generality of the Superposition Hypothesis . Invest. Ophthalmol. Vis. Sci. 2003;44(13):1996.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Purpose: The Superposition Hypothesis states that the binocular vision of newborn infants blends together the incoming signals from the two eyes as they arrive at the primary visual cortex. The eye-of-origin information being lost, neither stereopsis nor binocular rivalry is possible. Binocular blending is thought to be replaced by stereopsis and rivalry around age 3 months. The main evidence for the Superposition Hypothesis is a preferential looking (PL) experiment in which 8-12-wk-old infants fixated a rivalrous (for adults) dichoptic plaid in preference over a fusible grating of parallel lines. This result is thought to show that binocular blending occurs even when very different stimuli are presented separately to the two eyes. We attempted to repeat that important experiment. Methods: The stimuli were two 10° rectangular fields of stripes rear projected onto a projection screen. The stripes (stripewidth=1°; duty cycle=1/3; 67 cd/m2) were binocularly dissociated using red/green stereo glasses or circular polarizers. Experimental (rivalrous) stimuli were dichoptic plaids, with vertical stripes presented to one eye and horizontal stripes presented to the other eye. Control (fusible) stimuli were horizontal stripes presented in register to the two eyes. The right/left positions of the experimental and control stimuli were randomized across trials. We ran 40 PL trials weekly on 20 infants. We used Julesz random-check stereograms to test for stereopsis. Recults: Stereopsis appeared at 9 wks, but infants did not preferentially fixate the dichoptic plaid at any age between 5-16 weeks. Data collected using red/green glasses showed a smooth progression from no preference at age 5 wks to 80% preference for the fusible control stimulus starting at age 10 wks. Data collected using polarizing glasses also showed a preference for the control stimulus at ages 7-8 wks and at 10 wks, in excellent agreement with the data collected using the red/green glasses. Conclusions: Our results suggest that blending of the visual responses to rivalrous stimuli is not a general feature of the pre-stereoptic infant visual system. 1. Held, R, Binocular vision, in Neonate Cognition: Beyond the Blooming, Buzzing Confusion, V Mehler, Ed, 1985, Erlbaum Hillsdale, NJ 2. Shimojo, S, et al, Pre-stereoptic binocular vision in infants. Vis Res, 1986. 26: 501.
This PDF is available to Subscribers Only