How Much Can We Boost IQ and Scholastic Achievement?

Arthur Jensen argues that the failure of recent compensatory education efforts to produce lasting effects on children’s I Q and achievement suggests that the premises on which these efforts have been based should be reexamined. H e begins by questioning a central notion upon which these and other edu­ cational programs have recently been based: that IQ differences are almost en­ tirely a result of environmental differences and the cultural bias of I Q tests. A fter tracing the history of I Q tests, Jensen carefully defines the concept of IQ , point­ ing out that it appears as a common factor in all tests that have been devised thus far to tap higher m ental processes. H aving defined the concept of intelligence and related it to other forms of mental ability, Jensen employs an analysis of variance m odel to explain how IQ can be separated into genetic and environmental components. H e then discusses the concept of “ heritability," a statistical tool for assessing the degree to which individual differences in a trait like intelligence can be accounted for by genetic factors. H e analyzes several lines of evidence which suggest that the heritability of intelligence is quite high (i.e., genetic factors are much more important than environmental factors in producing I Q differences). A fter arguing that environmental factors are not nearly as important in deter­ m ining I Q as are genetic factors, Jensen proceeds to analyze the environmental influences which may be most critical in determining IQ . H e concludes