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Carl Granrud, Sherryse Corrow, Alan Gilchrest, Jordan Mathison, Albert Yonas; Four-month-old infants exhibit lightness constancy. Journal of Vision 2011;11(11):416. doi: 10.1167/11.11.416.
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© ARVO (1962-2015); The Authors (2016-present)
Perceptual constancies allow us to perceive properties of the distal environment despite variations in proximal stimulation. For example, adults are able to perceive the reflectance of an object despite changes in illumination; i.e., they are capable of lightness constancy. We investigated whether 4-month-old infants (n = 17) show evidence of lightness constancy. Infants viewed two faces through an aperture in a lighted enclosure. To measure a natural preference for a dark or light face, infants were presented with two pre-test trials under either low (group 1) or high (group 2) illumination. Infants were then habituated to either two white faces under low illumination (group 2) or two dark grey faces under high illumination (group 1). The luminance values for the faces during habituation were matched for the two groups. In test trials, infants were again shown the white face and the gray face under the same illumination levels presented in the pretest trials. Therefore, after habituation, one of the two faces was novel in reflectance while the other was novel in luminance. For each infant, a novelty preference was calculated by dividing the amount of time spent looking at the face that was novel in reflectance by the total looking time. Following habituation, infants showed a 58% preference for the face with the novel reflectance (p = 0.015). We also calculated the change in looking preference between the pre-test trials and post-test trials. There was a 12% greater preference for the novel reflectance in the post-test trials than the pre-test trials (p = 0.007). These results indicate that 4-month-old infants recognize an object's reflectance across changes in luminance. This indicates a degree of lightness constancy by 4 months of age. Our findings are consistent with those of Chien, Bronson-Castain, Palmer, & Teller (2006), the only previous study on lightness constancy in infants.
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