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Inhibition Deficits of Serious Delinquent Boys of Low Intelligence

NCJ Number
Criminal Behaviour and Mental Health Volume: 17 Issue: 5 Dated: 2007 Pages: 274-292
Roos Koolhof; Rolf Loeber; Evelyn H. Wei; Dustin Pardini; Annematt Collot D'escury
Date Published
19 pages
This study examined whether the insufficient development of appropriate inhibitions is the source of the link between low intelligence (IQ) and delinquent behavior in serious delinquent boys.
The study found that deficits in inhibition were important in the development of delinquent behaviors, especially among low IQ boys. Boys with serious delinquent behavior were all impulsive, regardless of IQ level; however, the serious delinquents with higher IQ had a more developed cognitive control system. Seriously delinquent boys with low IQ, on the other hand, exhibited the highest levels of cognitive and behavioral impulsivity. There were no differences between low IQ and higher IQ serious delinquents on measures of empathy and guilt feelings. Deficits on these characteristics were associated with serious delinquents as a whole. Compared with higher IQ serious delinquents, low IQ serious delinquents were exposed to more risk factors, such as low academic achievement, being old for their grade, depressed mood, and poor housing. Interventions for low IQ boys should focus on remedying behavioral impulsivity as well as cognitive impulsivity. Study participants were from the middle sample (n=508) of the Pittsburgh Youth Study, who were regularly monitored from ages 10-13. In the summer of 1990, 430 of the boys (84.6 percent) were assessed as part of a substudy on impulsivity and psychopathology. In the impulsivity study, IQ scores and impulsivity measures were administered, and data were collected on psychopathy and empathy. This study expands on earlier followup findings based only on official records of delinquency up to age 23. On the basis of the measures of IQ and delinquency, the following 4 groups were developed: higher IQ non-to-moderate delinquents (n=219), low IQ serious delinquents (n=39), low IQ non-to-moderate serious delinquents (n=21), and higher IQ serious delinquents (n=149). 7 tables and 64 references