Describes why birth order interests both parents and researchers, discussing what really causes apparent birth order effects on intelligence, examining problems with using cross-sectional intelligence data, and noting how to move beyond cross-sectional inferences. Explains the admixture hypothesis, which finds that family size is much more…

Characterizes intelligence in terms of learning processes and uses the concepts and methods of other disciplines to understand how the conditions responsible for the development of its constituent processes and the manner of their organization lead to variations in effectiveness of intellectual functioning. (Author/JM)