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Friday, September 3, 2010

Criminology - Intelligence and Crime



Early criminologists maintained that many delinquents and criminals have below average intelligence and a low I Q causes criminality. Criminals were believed to have inherently substandard intelligence and thus seemed naturally inclined to commit more crimes than more intelligent persons. Furthermore, it was thought that if authorities could determine which individuals have low I Q’s, they would be able to identify potential criminals before they commit socially harmful acts.

If there seems to be relation between criminality and intelligence the nature of that relation is both interesting and unclear. Apparently these individuals have difficulty in dealing with abstract concepts and reasoning, which reduces their ability to forsee the consequences of any actions either to themselves or to others. They may thus be less likely to be deterred by the possibility of detection, conviction and punishment, or by compassion or empathy of victims. This lack of intellectual capacity may be linked to number of factors.
1. First it could be the result of different or reduced brain functioning. The frontal lobes of brain controls abilities such as abstract reasoning, comprehension of abstract concepts, forward planning and aticipation of problem, self control-partiularly of impulsive and socially unacceptable behaviour.
2. Secondly the abilities set out above are those found to be problematic in cognitive learning and Farrington in 1994 suggests that some families are less likely to develop abstract reasoning in their children. A third suggestion links lack of intellect to failure to go beyond first stage of moral development. In Kohlberg’s scheme this is preconventional stage, which he says typifies many criminals

Social scientists had a captive group of subjects in Juvenile Training Schools and Penal Institutions, they began to measure the correlation between IQ and Crime by testing adjudicated offenders. Thus inmates of penal institutions were used as a test group around which numerous theories of intelligence were built, leading ultimately to the Nature versus Nature controversy.

There are different types of intelligence tests, with some using words or numbers and requiring cultural knowledge (like vocabulary), and others using shapes, designs, and only requiring simple, universal concepts (like up/down). Some intelligence tests are among the most accurate of all psychological tests and assessments. The brain processes underlying intelligence are becoming more understood, and current research is looking at speed of neural transmission, glucose (energy) uptake, and electrical activity of the brain. Some theories of intelligence look at the efficiency of information processing, and other theoretical models look at general adaptability


Nature theory argues that intelligence is largely determined genetically, that ancestry determines IQ and that low intelligence is linked to criminal behaviour. When newly developed IQ tests were administered to inmates of Prison’s and Juvenile Training Schools in the first decades of the century, the Nature position gained support because the inmates scored low on the tests.
In 1920 Henry Goddard found that many institutionalized persons were ‘feeble minded’ and concluded that half of all Juvenile Delinquents were mental defectives.
In 1926 William Healy and August Brouner tested groups of delinquent boys in Chicago and Boston found that 37% were subnormal in intelligence. They concluded that delinquents were ten times more likely to be mentally deficient than normal boys.
These were the proof that low IQ scores indicated potentially delinquent children and that a correlation existed between innate low intelligence and deviant behaviour. IQ tests were believed to measure the inborn genetic makeup of individuals and many Criminologists accepted the idea that individuals were predisposed towards delinquency and adult criminality.


The rise of culturally sensitive explanations of human behaviour in the 1930’s led to the nurture school of intelligence. It states that intelligence must be viewed as partly biological but primarily sociological. Nurture theorists discredit the notion that person’s commit crimes because they have low IQ’s. Instead they postulated that environmental stimulation from parents, relations, social contacts, peer groups and innumerable others create a child’s IQ level and that low IQ scores are recorded among criminals, theses scores reflect the cultural backgrounds of criminals and not their mental ability.

Studies challenging the assumption that people automatically commit crimes because they have low IQ’s began to appear as early as 1920’s. John Slawson studied 1543 delinquent boys in the New York institutions and compared them with a control group of New York city boys in 1936. Slawson found that although 80% of the delinquents achieved lower scores in abstract verbal intelligence. These results indicated possibility of a cultural bias in portions of IQ tests. He found no relationship between number of arrest, offences and IQ.


Although the alleged IQ-crime link was dismissed by the main stream criminologist, it once again became an important area of study when respected crminlogist Travis Hirschi and Michael Hindelang published a widely read 1977 artilce linking the two variables.

Hirschi and HIndelang concluded that ‘the weight of evidence is that IQ is more important than race and social loss’ for predicting criminal and delinquent involvement. The major differences exist between criminals and non criminals within similar racial and social class categories. They propose the idea that low IQ increases the likelihood of criminal behaviour through its effect on school performance. That is, youth with low IQ’s do poorly in school and school failure and academic incompetence are highly related to delinquency and later to adult criminality.

Richard Herrnstein and Charles Murray’s influential but controversial book on intelligence- The Bell Curve firmly advocates the IQ-crime link. The research showed in this book tries to prove that adolescent with low Q are more likely to commit crime, get caught, and to be sent to prison. Kids with higher IQs seem to be protected from becoming criminals by their superior ability to succeed in school and in social relationships. Both the eminent authorities concluded that criminal offender have an average IQ of 92, about 8 points below the mean.


It is reasonable to expect that those with a lower IQ are less able to avoid detection. Also, once detected they will be less able to give a good account of their activities, so they are more likely to end up in court, where they may receive a harsher sentence because of their inability to explain themselves. It is also worth noting that criminal activity which are likely to be committed by high intellect are generally less likely to be discovered, and are less likely to form the basis of prosecution. All these factors may lead to over-representation of those with low IQs in the statistics.
Far from testing the innate intelligence or intellect, it assesses the individual’s school level, i.e., measure level of comprehension and vocabulary. The scores will therefore reflect educational attainment or cultural background rather than potential intelligence. If studies test educational attainment, then clearly those will suffer whose education is not as thorough. Some claim that non-verbal studies are therefore better indicators of ability than verbal tests and some studies found that delinquents perform better on these tests than on verbal ones
Others allege that IQ tests simply measure class bias. The types of skills which are measured are not objective, but rather represent a cultural skill which is most likely to be held by, and be useful to, a middle-class urban tasks, such as ability to tie a shoe lace, to test intelligence, she would be labeled as ‘low intelligence’ often performed better than the normal high performers, and the low IQ lower-class individuals performed better on these tasks than did low IQ middle-class individuals.

There are therefore some inherent problems in making a link between criminality, delinquency and intelligence. The Cambridge study certainly suggest that there may be some link, but it is impossible to assess how direct it is.


It is unlikely that IQ Criminality debates will be settled soon. Measurement is behest with many methodological problems. The well documented criticisms suggest that:
a. IQ tests are race and class biased.
b. IQ tests are unable to explain crime patterns.

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