A study that followed the lives of young males for 20 years has found that cognitive ability predicted whether the person was likely to engage in violence or theft if they had a tendency for antisocial behaviour.

Way back in ’79, the researchers recruited 698 males from 12 to 18 years of age from a random telephone survey in New Jersey. They kept in contact with them until the year 2000.

The researchers interviewed the participants and asked about any antisocial behaviour or offences.

They also tested the participants using neuropsychological tests of verbal IQ and executive function – the ability to co-ordinate mental resources that is closely linked to the frontal lobes.

In the males who did end up engaging in antisocial behaviour, the ones with cognitive difficulties tended to be violent, while the ones who were cognitively more able tended to steal.

In other words, low mental ability was associated with violence while the brighter individuals tended to engage in theft.

This could be because successful theft could require more thought, from planning a robbery to tricking another individual, whereas successful violence just requires a target.

One of the difficulties in interpreting these sorts of studies, is that they rely on participants admitting their own offences, so maybe more intelligent people are likely to describe their crimes differently.

However, it certainly wasn’t the case that more able people simply kept quiet about antisocial behaviour, as both reported wrongdoings, but of a different type.

UPDATE: Romeo Vitelli makes an interesting point in the comments:

All things being equal, theft is regarded as being less serious than violence is. Given that this study depends on self-report, are the ones who commit violence less likely to admit to committing violent crimes than the ones who commit theft?

Link to abstract of scientific paper.

Link to brief jargon-free summary.