Where in the brain, exactly, is intelligence? Is a high I.Q. just a result of a flawed test – or do high-I.Q. brains have specific, measurable differences from others? Answers await, Intrepid Reader – but first we have to make sure we’re asking the right questions.
Let’s start with the big news: a study just published in the Journal of Neuroscience reports that when a certain area of the frontal lobe has unusually wide and active connectivity, a higher I.Q. tends to follow. The trouble is, though, that a high I.Q. only reflects certain types of mental abilities – so what this discovery really means is that a certain functional network in the brain plays a major role in certain kinds of smart thinking.
In fact, it makes perfect sense that the brain region we’re talking about here – the left lateral prefrontal cortex (lPFC) – would be central to the kinds of thought processes that earn you high I.Q. scores: namely, arranging logical steps and figuring out abstract rules. The wider and stronger the lPFC’s connections are, the more neural processes it can involve in its orderly calculations. And yet, while there’s no doubt that those calculations are some of the human brain’s most powerful and effective abilities, they’re only a few of the many skills we recognize as “intelligent.”
The limitations of I.Q. tests are rooted in the 19th century, when British and American scientists began developing the first intelligence tests. In those days, a commonly accepted assumption was that people of European descent had the highest intelligence on earth – so, naturally enough, researchers came up with tests on which well-educated Westerners tended to score the highest. And this might all just be an embarrassing historical footnote – except that today’s I.Q. tests still produce racially and culturally biased results.
What’s more, the reasons for those biases aren’t always clear-cut: a person’s individual attitudes about tests, school, and intelligence may influence his or her score as much as any cultural bias in the test questions. (Having grown up in a small town in West Texas, I know firsthand how it feels to be pressured to hide your intellect – even to be ashamed of it.)
Meanwhile, studies have found that it’s fairly easy to “outsmart” an I.Q. test – to teach students tricks and tactics for achieving high scores. This would seem to imply either 1) that a few weeks of practice drills can significantly raise a person’s intelligence, or 2) that the test is just measuring proficiency in a specific set of teachable skills.
In the later half of the 20th century, researchers like David Wechsler tried to expand the range of I.Q. tests, developing much more precise metrics for assessing verbal skills, spatial reasoning, ability to identify patterns, and so on. But by the early 1980s, researchers like Howard Gardner were insisting that some kinds of intelligence – and, in fact, many aspects of what we call “genius” – simply can’t be measured with a system like I.Q. assessment.
Gardner’s theory of “multiple intelligences” distinguishes linguistic and logical types of intelligence – the types that result in high I.Q. scores – from types like musical intelligence (the ability to recognize and compose pitch and rhythm) and intrapersonal intelligence (the ability to understand one’s own motivations and feelings).
Today, though, researchers have narrowed the field down to two intelligences: fluid intelligence (the ability to solve problems in novel situations) and crystallized intelligence (the ability to remember facts and use specific skills). Even so, it’s clear that intelligence isn’t just one attribute, but an interrelated collection of traits.
Part of what it means to be intelligent is having a lateral prefrontal cortex that does its job well; and part of what that means is that it can effectively communicate with the rest of the brain.
In other words, a well-connected lPFC is a handy thing to have, but it’s just one aspect of intelligence. It’s definitely got its benefits – it keeps you open-minded, and it may even help you stick to a healthier diet. On the other hand, it also makes you more likely to experience anxiety and depression, to develop schizophrenia, to enjoy drugs (especially psychotropics), and to suffer all kinds of expectation frustration. The upside of all these discoveries, though, is that the better we understand this lPFC network, the more precisely we’ll be able to diagnose and treat these kinds of troubles.
As you can see, intelligence (in all its many-splendored forms) isn’t exactly a process or a trait – it’s more a way of connecting; of assembling disparate thoughts, feelings and ideas into Gestalts: wholes that become more than the mere sum of their parts. That connectivity can be both a blessing and a curse – but in any case, it’s one of the core reasons your brain can conceive such strange and unique ideas as art and language – and even turn inward and contemplate itself.