Taylor (1980) claims to show that the similarity in IQ between monozygotic twins reared apart found in prior studies is due to similarity in their environments. A reanalysis using Taylor's classification of environments but an alternative IQ measure shows that his findings do not constructively replicate. (Author/RD)

We aimed to design alternative estimates of pre-morbid/prior intelligence to the National Adult Reading Test (NART) and the Spot-the-Word (STW) in order to tap non-vocabulary based knowledge stores. The rationale for the development of the new tests was that more cognitively able individuals acquire and retain more "singular facts" from their…

Scarr and Weinberg's results (Intelligence, 1977) are compared to those of similar adoption studies and found to be quite similar, despite the transracial adoption patterns in Scarr and Weinberg's sample. The author also suggests that the major contribution of behavioral genetics to psychology may be our increased understanding of the environment.…

Support for the confluence model of intellectual development has come from analyses of family size-birth order means of large aggregate data sets. Analyses of individual scores do not substantiate the confluence model, as explained variance is markedly reduced. The study of family interaction variables utilizing longitudinal data is recommended.…

Explanations of differences in IQs of Northern and Southern Blacks focus on selective migration (hereditarians) or environmental causes such as education, discrimination and cultural deprivation. In this paper the environmentalist position is questioned and certain neglected features of Lee's data are construed as providing strong evidence for…

The assumption that a singular biological resource pool embedded in the central nervous system results in differences in macrolevel outcomes because of the constraints it imposes on efficiencies of microlevel processing is refuted. Moderating effects on the causal pathways between microlevel and macrolevel performance are discussed. (SLD)

Extensive data on twins, nontwin siblings, siblings separated by adoption, and parent-child similarity indicate that the heritability of intelligence is closer to .50 than to .70. Differences could be due to environmental or genetic changes in the population, or to methodology. (Author/CP)

Wolff has recently reinterpreted the data of Lee to indicate that Black migration from the south to Philadelphia had been selective in an IQ-relevant manner. However, Wolff's deduction from Lee's data is shown to depend entirely upon an assumption about cumulative IQ deficit in southern Black children. (Author/CTM)

Kamin has contended that arguments presented in Wolff are too weak to justify selective migration. Although Kamin's critique points up the need for closer scrutiny of the cumulative-deficit phenomenon, it fails to refute Wolff's conclusion that selective migration is partly responsible for the North-South Black IQ differential. (Author/CTM)

A model-fitting analysis of the covariance structure of an intelligence quotient (IQ) data set is reported using a model that considers additive and nonadditive genetic parameters and shared and nonshared environment parameters that permit different estimates for different types of relatives. The use of LISREL for such purposes is reviewed. (SLD)

A reply to Plomin's critique and some criticisms of Munsinger's review of adopted child literature are presented. Selective bias in adoptee samples, implicit assumptions in models that lead to heritability estimates, and problems produced by lack of an accepted model of environmental transmission are also discussed. (Author/RD)

Swedish longitudinal studies of twins support Scarr-Salapatek's explanation of nature-nurture influences on intelligence. This model predicts more genetic variance in test results for advantaged than disadvantaged groups. Jensen's work, however, suggests equal amounts of variance among different social classes. (Author/CP)