The fact that males outperform females on specific spatial tests is not generally disputed, but the explanations for these differences are controversial. This paper highlights unresolved issues, such as definitions of space and measurement of abilities, and illustrates problems of interpretation of research regarding sex differences. (Author/HS)

A study of 700 children (ages 5-12) investigated whether children's conceptions of and expectations of friendship are determined by chronological age or by mental age. Results found children of differing intellectual abilities pass through the five conception stages of friendship at different ages and at different rates. (Contains 4 references.)…

The confluence model of cognitive development was tested on 7,060 children. Family size, sibling order within family sizes, and hypothesized age-dependent effects were tested. Findings indicated an inverse relationship between family size and the cognitive measures; age-dependent effects and other confluence variables were found to be…

Cognitive, academic, and behavioral characteristics of 42 children with learning disabilities were assessed from identification at age 6-7 to the age of 11.5. At endpoint, resource students showed a drop in verbal intelligence quotient and lower achievement compared to mainstreamed students, though there were no differences at the time of…

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…

A case study of a pair of extremely deprived twin boys focuses on their verbal communication. Talkativeness alone was not regarded as a measure of intelligence, but attention was paid to the less talkative twin's greater use of imaginative speech. Speculations are made on the evolutionary role of creative speech. (IS)