Eighty at-risk infants were administered the Mental and Motor Scales of the Bayley Scales of Infant Development at 6 and 12 months of age. Test-retest reliability scores of .71 on the Mental Scale and .69 on the Motor Scale were obtained. (Author/JDD)

Two studies on cognitive performance in mentally retarded children are reported. In the first study, the Bayley Scales of Infant Development were administered to 56 mentally retarded children, aged 2 to 6, to determine the possibility of discerning subsets of items that form a developmental pattern of interrelated subscales, using the SCAMMO scale…

Down Syndrome children (N=229), aged 1-83 months, from Australia, Canada, and Germany were tested using the Bayley Scales of Infant Development. Test performances on the Bayley's Mental and Motor scales were not dissimilar, leading to the conclusion that young Down Syndrome children from different countries with relatively comparable standards of…