A new procedure designed to assess contrast and color vision in young infants

Mercer, Michele E. (1989) A new procedure designed to assess contrast and color vision in young infants. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (8MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

An enduring practical problem in studying human visual development is to obtain enough data to evaluate the vision of individual infants. With this problem in mind, we have produced a new test of basic color vision using Munsell Hues and a method patterned after the Teller Acuity Cards (TAC). -- In our procedure, we first evaluate an infant's sensitivity to luminance contrast. The baby is shown large gray cards (21.5 x 56 cm) that have a 7.5 x 12 cm gray "standard" patch of the same luminance on the left or the right side, and a gray "test" patch of different luminance on the other side. Like the TAC procedure, a "blind" observer attempts to correctly judge the location of the test patch. The procedure continues until the smallest detectable luminance increment and decrement is determined. Next, we test the infant with chromatic test patches. To eliminate brightness cues, the relative luminance of the chromatic patch and the gray background is varied systematically (Teller & Bornstein, 1987) in equiluminant steps over a wide range (about 1 log unit) centered around an adult brightness match. The step size (thus, the number of cards needed for each chromatic test) is determined by the subject's sensitivity to contrast in the first phase. -- We used the Color/Contrast Cards to test 70 2- and 3 month-olds with four broad-band chromatic stimuli, namely a red (dominant wavelength = 660 nm), a (580 nm) yellow, a (520 nm) green, and a (475 nm) blue. In approximately 20 minutes, 83% of 2-month-olds and 87.5% of 3-month-olds completed the contrast phase and at least one of the four chromatic stimuli, and of these, 37% of 2-month-olds and 34% of 3-month-olds completed all four chromatic stimuli. Both groups of infants were significantly better at detecting luminance decrements than increments. 3-month-olds discriminated all four chromatic stimuli from gray. In contrast, 2-month-olds discriminated the red and blue from gray but failed to discriminate the yellow and green from gray at relative luminances close to the adult brightness match. Reasons for 2-month-olds' "failures" are discussed in detail. -- In general, the procedure was successful. Over a relatively short period, we could test an infant's sensitivity to luminance contrast, her/his chromatic-achromatic discriminations, and the relative luminances at which the infant "fails" to make these discriminations. In future, the Color/Contrast Cards should prove to be clinically useful for screening younger infants and handicapped children, as well as experimentally useful in providing information about the development of color vision and its underlying mechanisms.

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