A reanalysis of B. Inhelder's (1968) data concerning cognitive development among retardates was performed by selecting from the original 159 subjects a sample of 104 educable mentally retarded Ss (7-19 years old) who were diagnosed as fixated or nonfixated at three of the cognitive stages postulated by Jean Piaget. The results indicated that among…

This report discusses the outcomes of a study that examined 216 comparably aged children and adolescents (ages 2-18) with fragile X or autism to determine whether longitudinal change in cognitive ability and adaptive behavior was similar in the two groups. Results found decreases in Intelligence Quotient scores in young children with fragile X as…

Reports on the findings of a comparative study of mental abilities of Mexican and American children. Discusses age, sex, social class, and urban-rural differences, as well as cultural differences. (SS)

This final report reviews the second phase of a life-span study of boys with fragile X syndrome (FSX), the most common known inherited cause of mental retardation. Males with the syndrome are more severely affected than females and in males, delays are usually evident in all the developmental domains, although cognitive and communication skills…