Unfortunately for those who wish to deny IQ (sometimes known as ‘G’ for general intelligence) is real, the data and the science continue to pile up against such beliefs. In fact, studies repeatedly confirm the reality of IQ and the connections between a variety of both positive and negative life outcomes and intelligence. Not only do studies of the general population support the reality of IQ, but even studies specifically conducted inside prison systems confirm those claims.
For example, studies consistently reflect the fact that chronic or repeat criminal offenders have a lower average IQ than non-offenders. This is true among both juvenile repeat offenders (who average about 92) and adult repeat offenders (who average about 85). IQ tests are normed for a populace to 100. Every few years the tests are re-normed due to IQ drift, which tends to be upwards (commonly referred to as the ‘Flynn effect’). The 15 point difference between the norm for the general population and that of chronic offending adults is known as 1 standard deviation.
More evidence comes from a study conducted in the Texas prison system which found that more than 20% of criminal offenders had an IQ below 80. IQ’s at such a level begin to seriously impede a person’s chances at life success and it is thought that a life of crime then becomes an alternative (dangerous and risky) path for such persons. Additionally, those who have IQ scores around 80 and below have significant problems in balancing short-term vs long-term desires. This is sometimes referred to as the ability to delay gratification and is related to time-preference (‘I want what I want and I want it now by any means necessary’ vs ‘I want X but will work slowly, methodically, and legally or morally to attain it’).
This is not, however, to say that those of moderate to high IQ do not commit crimes. The presumption here is that those of higher IQ tend to commit crimes which they are able to conceal or are harder to detect for a host of reasons. Still yet, chronic offenders do tend to be involved in far more physical crimes: burglary, assault and battery, car-jacking, drunk-driving accidents, homicides, and the like. Much of this is supported in the study linked below:
Intelligence and Crime - Criminal Justice - IResearchNet
The majority of studies have found IQ differences between offenders and nonoffenders (e.g., Ellis &Walsh, 2003). On…
There are a number of theories about why this should be the case. Probably the leading contender right now is a theory about the importance of language development. Since language is a human universal, it would stand to reason that those who suffer from significant linguistic deficits would have a number of negative life outcomes. Note that this is not an argument about poverty which is the most common argument offered to explain criminality. In fact, I find poverty to be a complete non-explanation.
I grew up poor and in an impoverished community. One thing that always struck me was the degree to which virtually everyone I knew were decent, upstanding and, largely, law-abiding people who were either down on their luck or had nowhere to work because there were so few job opportunities. I did not see these people going out and robbing their neighbors, committing murder, rape, or other madness and mayhem. In fact, it was so rare to even see a police car in the neighborhood in which I grew up that it instantly became a big scandal and subject of much gossip anytime someone saw the police.
This clued me in early on that the kneejerk explanation that poverty causes crime did not meet with my firsthand personal real-world experience. In other words, it failed to pass even the most minimal level of common sense empirical testing. I did, however, note that those who did chronically or repeatedly get involved in various types of criminality or immorality seemed to have certain personality characteristics and that those personality traits were sometimes common within entire families. This caused me to wonder if some people may be hard-wired to be troublemakers.
In other words it would stand to reason that a biologically-based explanations work better than social or environmental explanations. Not that there is no influence from such sources, clearly it would be irrational to say that biology or genetics alone seal the deal. Below I link an article that offers other alternative hypotheses regarding IQ and crime:
I decided to put together a video/podcast that is more comprehensive than the current article and that is available here:
Finally, there is a recent prison inmate misconduct study that advances a similar contention: