Four hundred subjects 8 to 11 years old were given a modification of the Weigl Color Form Sorting Test in an attempt to assess the influence of chronological age, mental age, intelligence, and vocabulary level on the ability to utilize various numbers and different kinds of criteria of classification. (Author/MP)

This study found that 16 preschoolers with Down's syndrome attained higher age equivalents and standard scores in "socialization" than did 16 preschoolers with autism. Adaptive age equivalent was positively related to chronological age for children with Down's syndrome in all domains, but only in "communication" for children with autism.…

This study, involving 48 children and adolescents with Down's syndrome, found that chronological age and mean mental age collectively accounted for much of subjects' variability in vocabulary comprehension and syntax comprehension, with total passes on a hearing screening accounting for additional variability. (Author/DB)

Forty-nine children (ages 8-17) with mental retardation recognized facial expressions less accurately than did subjects without retardation who were matched on chronological age. Mental age-matched groups showed no differences in accuracy at a younger mental age, but a difference was found at an older mental age. (Author/JDD)

This study of 28 girls (ages 2-19) with Rett Syndrome found profound handicaps in the intellectual and adaptive areas, according to standardized tests. Subjects seemed capable of learning some self-help skills at a basic level. The Cattell Mental Age was significantly negatively correlated with chronological age. (JDD)