Intelligence and Violent vs. Nonviolent Offending
Evidence is accumulating that violent behavior is more closely linked with intellectual deficits than nonviolent antisociality (Barker et al., 2011, p. 63). Barker and colleagues have made this point strongly; they reported that a series of indicators of executive function and verbal ability were negatively associated with physical aggression trajectories, but not with theft trajectories. In fact, controlling for violent offending, measures of executive function and verbal intelligence were positively associated with theft trajectories in their study (Barker et al., 2007). Walsh (1987) found a negative association between IQ and violence, but a positive association between property crime and IQ. In another study, the authors report a negative correlation between Wechsler Adult Intelligence Scale—Revised (WAIS-R) scores and violence but not between the WAIS and nonviolent offenses (Bernat, Hall, Steffen, & Patrick, 2007). A small number of studies compare violent and nonviolent offenders. In several studies, violent offenders have had significantly lower IQ scores than nonviolent ones (Holland et al., 1981). Dionne (2005) also describes a succession of findings from the Quebec Newborn Twin Study consistent with this pattern.