Theoretical predictions, based on the confluence model, were made for data from six national surveys of intellectual performance, each relating intellectual performance scores to family configuration variables. The confluence model was capable of accurate prediction in all cases when three parameters were estimated. (Author/RD)

Discusses the research debate over the question whether intelligence diminishes as a function of birth order. Presents a study of Zimbabwean children confirming the general downward trend of intelligence as a function of birth order. Addresses the influence of family size. (DB)

According to confluence theory, a child is helped or hindered in intellectual development according to the average absolute intelligence (mental age) in the family when the child is born. An analysis of test scores, family information, and socioeconomic data of 36,000 college applicants in Colombia failed to support this theory. (Author/CP)