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Maria Pereverzeva, Davida Y. Teller; Simultaneous color contrast in 4 months old infants is revealed by a temporal modulation paradigm. Journal of Vision 2005;5(8):1028. doi: 10.1167/5.8.1028.
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When a test stimulus is embedded in a chromatic surround, adult subjects report that temporal modulation of the chromaticity of the surround induces a corresponding temporal modulation of perceived color of the test stimulus, in phase with the surround modulation. This modulation can be nulled by modulating the test stimulus, in phase with the surround. We use this phenomenon to address the question of simultaneous color contrast in infants.
In a pilot study, adult subjects viewed a modulating test field in a surround that modulated in purity from 38% purity Blue-Green (BG) to white at 1.2 Hz. They determined the modulation of the test field, Tnull, required for the test to appear unmodulated. Tnull modulated from white to 15% purity Red.
Two experiments were carried out on 23 4-mo-old infants. In both experiments, the infants viewed a display in which two circular 10° test stimuli were embedded 10° to the right and left of center in a 48° by 64° surround. The stimuli were Tw, stationary white, and Tnull, defined above. The luminances of the tests and surrounds were 15 and 20 cd/m2 respectively. In Expt1, the surround chromaticity was constant at 19% purity BG. In Expt2, as in the adult pilot study, the surround was modulated from 38% purity BG to white, in phase with the modulation of Tnull. The two surrounds had equal time-average chromaticity.
If infants simply prefer to look at the stimulus that is physically flickering and maximally different from the surround, they should prefer Tnull over Tw in both experiments. However, if infants have adult-like simultaneous color contrast, the temporally modulated surround should decrease the perceived modulation of Tnull, and thus decrease the infant's preference for Tnull.
The results show a significant decrease of preference for Tnull in Expt2 (Delta = 14% +/− 2%), consistent with the conclusion that 4 months old infants have simultaneous color contrast. Additional experiments will be discussed.
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