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Karen R. Dobkins, Rain G. Bosworth, Joseph P. McCleery; Effects of gestational length, gender, postnatal age, and birth order on visual contrast sensitivity in infants. Journal of Vision 2009;9(10):19. doi: 10.1167/9.10.19.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate effects of visual experience versus preprogrammed mechanisms on visual development, we used multiple regression analysis to determine the extent to which a variety of variables (that differ in the extent to which they are tied to visual experience) predict luminance and chromatic (red/green) contrast sensitivity (CS), which are mediated by the magnocellular (M) and parvocellular (P) subcortical pathways, respectively. Our variables included gestational length (GL), birth weight (BW), gender, postnatal age (PNA), and birth order (BO). Two-month-olds ( n = 60) and 6-month-olds ( n = 122) were tested. Results revealed that (1) at 2 months, infants with longer GL have higher luminance CS; (2) at both ages, CS significantly increases over a ∼21-day range of PNA, but this effect is stronger in 2- than 6-month-olds and stronger for chromatic than luminance CS; (3) at 2 months, boys have higher luminance CS than girls; and (4) at 2 months, firstborn infants have higher CS, while at 6 months, non-firstborn infants have higher CS. The results for PNA/GL are consistent with the possibility that P pathway development is more influenced by variables tied to visual experience (PNA), while M pathway development is more influenced by variables unrelated to visual experience (GL). Other variables, including prenatal environment, are also discussed.
*Significant values at p < 0.05. Note that r values for correlations of GL, PNA, and BW with both luminance CS and chromatic CS are presented within the same table even though the two types of CS were separated in the MRA.
*Significant values at p < 0.05, MS denotes marginally significant values ( p < 0.10). For continuous variables (PNA, GL, and BW), positive values indicate that a higher value of the variable predicts higher contrast sensitivity. For categorical variables (gender and birth order, BO), positive values indicate higher contrast sensitivity in boys than girls and higher contrast sensitivity in non-firstborn than firstborn infants. Also shown is the R 2 for the full model and the residual variance (RV) that is unaccounted for by the full model.
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