THE IQ/AGGRESSION CONNECTION
Numerous studies link low IQ to violent behavior, delinquency, and adult crime. In
fact, as Bruce Bower recently noted in Science News, "Intelligence deficits make up one
of the most firmly established characteristics of criminal offenders as a whole." But
critics suggest that this may simply mean that high-IQ criminals are more likely to
A new study by Peter Giancola and Amos Zeichner, however, suggests that IQ and
aggression are strongly linked even in non-criminal males. The researchers, who tested
30 males between the ages of 18 and 36 years, found "strong inverse correlations
between IQ and aggressive behavior under both high and low provocation conditions."
Subjects in the study were told that they would be competing with an unseen opponent
on a reaction-time test. They were seated in an experimental chamber and told to press
a lever immediately upon seeing a red light on a console. Each subject was told that
winning a trial would allow him to shock his opponent, while losing a trial would cause
him to be shocked by the opponent. Five levels of shock, ranging from imperceptible to
painful, were available.
(Researchers used a number of ruses to convince subjects that their opponents were
real. In reality, however, shocks were delivered to participants according to a
The researchers measured the intensity of the shocks administered by subjects to their
fictitious opponents, and found that lower-IQ subjects were significantly more likely to
deliver strong shocks than higher-IQ subjects. This was true even when the fictitious
opponents delivered mild shocks.
"These results help bolster the hypothesis that possessing a high IQ may serve as a
`protective factor' against the expression of anti-social or aggressive behavior,"
the researchers say. They note that their results support an earlier study by Kandel et al.
which found that criminals' sons who became criminals themselves had significantly
lower IQs than criminals' sons who did not participate in criminal activity.
Giancola and Zeichner add that "If this `protection' hypothesis is indeed correct,
children with IQs in the lower range of the distribution should qualify as the main
targets for violence prevention programs."
"Intellectual ability and aggressive behavior in nonclinical-nonforensic males," Peter R.
Giancola and Amos Zeichner, Journal of Psychopathology and Behavioral Assessment, Vol.
16, No. 2, 1994. Address: Amos Zeichner, Department of Psychology, University of
Georgia, Athens, GA 30602-3013.
"Criminal intellects," Bruce Bower, Science News, Vol. 147, April 15, 1995.