Individual differences in intelligence: A reappraisal of the confluence model

The confluence model posits that an individual's intellectual development is a function of the intellectual environment he or she is exposed to in the home. Families with many children spaced close together are presumed to have intellectual environments inferior to those of families with few children spaced far apart. To date, the major support for the confluence model has come from analyses of the family size-birth order means of large aggregate data sets. Analyses of the individual scores of some of those same aggregate data sets, however, do not substantiate the confluence model. Explained variance for the aggregate (90%+) reduce to less than 3% in the individual analyses. A recommendation is made to shift the focus of the confluence model from family configuration variables to family interaction varibles utilizing longitudinal data from individuals.