Intelligence and Crime

The study of intelligence in criminological research has ebbed and flowed considerably during the past century. In the first quarter of the 1900s, hundreds of studies categorized criminal offenders as "feebleminded" and "mentally deficient." Fifty studies conducted from 1910 to 1914 identified an average of 51 percent of institutionalized delinquents as feebleminded (Sutherland). In 1931, however, E. H. Sutherland challenged this prevailing view. He compared the IQ scores of adult offenders to those of army draftees—representative of the general population—and the two groups had nearly identical IQ levels. He concluded that intelligence was not a "generally important cause of delinquency" (p. 362). This rejection of IQ was widely accepted in the criminological literature through the mid-1970s. In 1977, Hirschi and Hindelang reviewed a half-dozen well-known empirical studies and concluded that IQ predicted delinquency as strong, if not more strongly, than race and social class—two variables prominently featured in criminological theory. This revisionist perspective stimulated greater interest in IQ and crime over the next two decades. In 1994, Herrnstein and Murray published their highly controversial book The Bell Curve in which they argued, among other things, that racial differences in crime rates resulted from racial differences in intelligence. This book has received widespread negative reaction and has possibly created a general backlash against studies of intelligence and crime.