A Simple Exercise To Boost IQ

My latest column in the WSJ is now online. It's about a forthcoming PNAS paper on the n-back test and fluid intelligence:

Can we make ourselves smarter? In recent decades, scientists have accumulated increasing evidence that our intelligence, at least as measured by the IQ test, is sharply constrained by genetics. Although estimates vary, most studies place the heritability of intelligence at somewhere between 50% and 80%. It's an uncomfortable fact, but not all brains are created equal.

Which is why there's so much buzz about a forthcoming study that complicates this assumption. Researchers at the University of Michigan found that it's possible to boost a core feature of human intelligence through a simple mental training exercise.

In fact, when several dozen elementary- and middle-school kids from the Detroit area used this exercise for 15 minutes a day, many showed significant gains on a widely used intelligence test. Most impressive, perhaps, is that these gains persisted for three months, even though the children had stopped training.

Scientists typically describe intelligence as consisting of two distinct components: fluid intelligence and crystallized intelligence. Fluid intelligence refers to the general ability to solve new problems and recognize unfamiliar patterns. Crystallized intelligence, by contrast, consists of particular kinds of knowledge. When children learn to count, for instance, they show gains on crystallized intelligence, even as their fluid intelligence remains constant. Scientists have typically regarded fluid intelligence as the aspect of our thinking that is most determined by genetics, since it can't be easily taught.

And yet these schoolchildren showed gains in fluid intelligence roughly equal to five IQ points after one month of training. The IQs of 68.2% of the populace fall within a 30-point range, so this is a significant change. These kids weren't learning facts they would soon forget. They were learning how to think better.

These improvements were triggered by a mental exercise known as the n-back task. The exercise is not fun, even when translated into videogame format. It begins with the presentation of a visual cue. For the kids in the experiment, the cue was the precise location of a cartoon character. In the next round, the cue is altered—the cartoon character has moved to a new location. The job of the child is to press the space bar whenever the character returns to a spot where it has previously been, and to ignore the other irrelevant locations. As the children advance in the task, these locations move further back in time, forcing them to sort through an increasing amount of information.

How does this tedious exercise boost intelligence? The crucial change concerned the nature of the children's attention. After repeatedly playing the n-back game, the young subjects were better able to focus on the necessary facts. As a result, they squandered less short-term memory on irrelevant details, such as cartoon locations they didn't need to recall. The children "got better at separating the wheat from the chaff across a variety of different tasks," says John Jonides, a senior author on the paper.

There are two important caveats to this research. The first is that not every kid showed such dramatic improvements after training. Initial evidence suggests that children who failed to increase their fluid intelligence found the exercise too difficult or boring and thus didn't fully engage with the training.

The second caveat concerns the relevance of the mental improvement. Scott Barry Kaufman, a cognitive scientist at New York University who was not involved in the research, believes that while this study has "incredibly important potential implications," it's unclear if the children's performance changed on anything besides an abstract intelligence test.

Still, this research promises to change longstanding beliefs about the nature of intelligence. Our IQ scores may be bounded by our genes, but it looks as if it's possible to significantly increase measured intelligence after only a few hours of training. "Intelligence is a lot like height," Prof. Jonides says. "We know that how tall you are is largely determined by the height of your parents. But we also know that better nutrition can make everyone a lot taller. Perhaps the n-back task is just an ideal form of mental nutrition."

Although we can't choose the brain we've been given, we can choose what that brain is paying attention to. All it takes is a little practice.

A few additional notes: If you're interested in learning more about this research - but are too impatient to wait for a future edition of PNAS - I'd suggest checking out previous papers from Jaeggi, et. al. on fluid intelligence and the n-back test.

There are also plenty of apps that feature the n-back test. I will not be linking to those. I have not played them and the scientists have not endorsed them. Caveat Emptor.

I also think it's worth reiterating an important caution raised by Scott Barry Kaufman. Although the IQ test has been widely used for decades, we still have a poor understanding of what it actually measures. As a result, there's tremendous debate about it's overall importance and how much of the individual variation in life success IQ scores can explain. (As one scientist told me, "The IQ test matters. It just doesn't matter as much as people think.") So I think it's worth wondering if this significant increase in fluid intelligence will show significant effects out of the lab. Will it actually lead the children to do better on their algebra homework? Will it lead to more productive employees? Will it improve problem-solving across domains? None of those questions have answers.

Lastly, there's an interesting connection between the mental skills improved by the n-back test - the ability to control attention, and thus ensure our working memory is filled with relevant facts - and the ability to exert self-control. While we used to assume that self-control was about gritting our teeth, outlasting that damn temptation, we now know that self-control is really about "the strategic allocation of attention." If you're thinking about the ice cream in the fridge, you're going to eat the ice cream, which is why you need to think about something else. (Our willpower is so weak that the only way we can resist anything is by finding a way to forget about it, directing the spotlight elsewhere.) So I'm curious if the n-back test might also improve measurements of self-control. Will it allow us to better allocate the scarce resource of working memory? Will we get better at not thinking about that pint of Rocky Road? Because as Angela Duckworth has demonstrated, the only variable that's more important than IQ scores when it comes to predicting academic success is self-control.