Comparison of the Revised and Original Versions of the Bayley Scales of Infant Development

Abstract

Differences between Mental Scale scores on the revised Bayley Scales of Infant Development(BSID-II) and the original test (BSID) were evaluated. Both versions of the measure were administered to 32 subjects, ranging in age from 3 to 28 months, in counterbalanced order. Inter-test correlations indicated that the two versions of the test were significantly correlated (r = .76, p < 0.05). Significant differences between scores on the BSID-II (M = 105.97) and the original BSID (M = 124.38) were observed (t(31) = 8.41, p < 0.05). Children below the age of 12 months displayed slightly larger discrepancies than children above 12 months of age. This discrepancy did, however, appear to increase significantly with the developmental levels of the children, with subjects scoring above one standard deviation on the BSID displaying larger discrepancies than those at or below the normal range. These findings are important for psychologists, early interventionists and other professionals involved in the assessment of infants and toddlers as they interpret scores on the new Bayley Scales. This information is especially pertinent for children whose performance is evaluated longitudinally, since they will likely score lower on the new test than they did on the original Bayley Scales. The lower scores may lead to subsequent increases in the number of children who qualify for early intervention and special education services. Therefore, these findings are also important for those involved in the development and evaluation of intervention programs for young children. The findings are considered in terms of their applicability across cultures.