The Birthdate Effect: A Maturational Effect?

There are high positive correlations between the percentages of learning disabled children and their months of birth in Hawaii. The relationships are similar for the sexes and do not decrease with age. The LD children born early or late in the year show differences in variability of IQ subtests and age of referral. This, together with a trend towards IQ differences, suggests that simple immaturity at school entrance is an insufficient explanation for the relationships observed. An investigation of the neuropsychological characteristics of early-born and late-born LD children is in progress.