Individual differences in contrast sensitivity functions: the first four months of life in humans.
Contrast sensitivity functions of forty 4-month-old human infants were measured using a preferential-looking method and the method of constant stimuli. Circular sinewave gratings varied from 0.27 to 1.08 c/deg, contained eight unattenuated cycles (with edges tapered to uniform gray), and rose to the desired contrast in 2 sec. Log contrast sensitivities for variables close in spatial frequency correlated more highly than those that were farther apart in these data, and in data of 1-, 2-, and 3-month-olds from Banks and Salapatek [(1981) Journal of Experimental Child Psychology, 31, 1-45]. Factor analyses yielded at least two frequency-tuned factors per age group. Monte Carlo simulations of a quantitative model that shifts spatial mechanisms to higher frequencies with age reproduced the results for 4-month-olds, but simulations of adultlike, unshifting mechanisms did not. The data are consistent with the following conclusions: (a) individual differences in the sensitivity of spatial mechanisms may explain some individual differences in CSFs; (b) factor analysis may help to estimate mechanism tuning; and (c) spatial mechanisms may shift to higher frequencies during development.
Peterzell
D H
DH
Department of Psychology, University of Colorado, Boulder 80309-0345.
Werner
J S
JS
Kaplan
P S
PS
D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008433:Mathematics; D008959:Models, Neurological; D009010:Monte Carlo Method; D010364:Pattern Recognition, Visual / Q000502:physiology; D012684:Sensory Thresholds / Q000502:physiology