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|Title:||The Perception of Contrast and Color by the Human Newborn|
|Authors:||Adams, James Russell|
|Abstract:||<p>This thesis investigated newborns' ability to detect contrast and to discriminate chromatic from achromatic stimulation. I studied newborns' sensitivity to contrast by taking advantage of their preference for patterned over unpatterned stimulation. Newborns (n=60) looked longer at checkerboards in which the checks contrasted by 11%, by 17%, by 23% and by 27% than at grey squares matched in mean luminance to the checkerboards, but showed no preference when tested with checks contrasting by 3% or 5%. In addition, the magnitude of their preferences increased as a function of increasing contrast. In order to examine contrast detection developmentally, 2-month-olds (n=24) were exposed to a series of contrasting checkerboards and the respective matching grey squares. The results showed that 2-month-olds demonstrated preferences for checkerboards with contrasts of 5%. of 11%, and of 23% but not of 3% over matching grey squares. However, 2-month-oIds' preferences did not increase with increasing contrast. These results suggest that newborns and 2-month-olds are much more sensitive to contrast than previous studies had indicated.</p> <p>In studies designed to test color perception, newborns were shown a series of colored-and-grey checkerboard patterns in which the difference in luminance between the color and the grey components was varied across a range centred at the luminance where adults would see the color and the grey as equally bright. It was assumed that with at least one of the patterns, newborns would not detect a brightness difference between the colored-and-grey checks. Therefore, newborns would be abIe to detect such a pattern only if they could detect its hue. In this case, newborns should show a preference for this pattern as well as all other checkerboards over the matched grey squares.</p> <p>Newborns were shown six green-and-grey (n=60), six yellow-and-grey (n=60), six red-and-grey (n=60) and six blue-and-grey (n=60) checkerboards and the matching grey squares. The results showed that regardless of the difference in luminance between the chromatic and achromatic checks, newborns demonstrated that they differentiated grey from green, from red, and from yellow. However, when viewing blue-and-grey checkerboards, newborns did not show a preference for two of the patterns over their matching grey squares. Secondly, the pattern of newborns' preferences for these blue-and-grey checkerboards over the matched squares was very similar to what it had been when newborns were shown achromatic checkerboards in Experiment 2. This pattern suggests that only contrast information was present when newborns viewed these "blue"-and-grey checkerboards. A subsequent experiment with 1-month-olds revealed that infants at this age were able to differentiate the blue from the grey checks in the checkerboards.</p> <p>These data constitute the first demonstration of color vision in newborns. They imply that newborns possess at least one functioning cone system and that at least some portion of the geniculostriate pathway may be operational. The data also suggest that there are limitations on newborns' color vision: Newborns appeared not to detect the short-wavelength hue. Moreover, the luminance at which their preference for a blue-and-grey stimulus disappeared is consistent with previous reports that young infants see short-wavelength light as relatively brighter than do adults.</p>|
|Appears in Collections:||Open Access Dissertations and Theses|
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