This belief is terribly destructive because it leads to a defeatist attitude (”I just can’t do any better than this in school”), it leads people to select easy tasks when they can (to ensure success so that they look smart) and it leads people to think of failure not as a chance to learn and improve, but as frightening feedback about their lack of innate ability. (Carol Dweck is the orginator of these important insights, and I recommend her book on the subject, Mindset).
In fact, people can become smarter, and new data indicate that it may be possible in a way that we had thought was impossible.
Two factors contribute to mental abilities: what you know, and your ability to work with what you know. When I say “work with” I mean combine in new ways, notice details of, make new comparisons, and so on. A limiting factor of smarts is one’s speed and facility in making these combinations. For example, you might calculate 8 X 16 in your head, but you would not try to calculate 341,963 X 789. Why not? The procedures to do the calculations are the same in both problems, but in the second you know that you would run out of “mental space.” The same space limitation applies in many mental tasks, for example, keeping several clauses in mind as one untangles the grammar of a complex sentence. People with more mental space (and who can use it more effectively) do better in school and are more successful in the workplace. Indeed, the amount of mental space you have correlates fairly well with scores on standard intelligence tests.
So a method of increasing people’s mental space would be of enormous educational significance. But no one has been able to find such a method. Rather, researchers have pointed to ways that one can cheat the limitation. Readily available factual knowledge is of tremendous help, as I’ve described in this article. For example, if you know that 9 X 7 = 63, you need not use valuable mental space to do that calculation as part of a more complex problem. (And indeed, knowledge of math facts is known to be an important component of competence in algebra and beyond.) But researchers have believed that mental space itself cannot be changed. As I put it in my recent book, “What you get is what you get.”
Recent research published in the Proceedings in the National Academy of Sciences indicates that that conclusion may have been wrong. Susanne Jaeggi and her colleagues claim that they have developed a training regimen that increases the size of working memory (the term researchers use for mental space). Plenty of researchers have tried giving people practice on standard working memory tasks. The typical finding is that people get better at the task with practice, but the improvement does not transfer to other tasks, leading to the interpretation that people improved by learning some strategies for that particular task; the improvement did not reflect improved working memory.
Jaeggi and her colleagues dug a little deeper and tried to develop a training task that didn’t just rely on keeping a lot of stuff in working memory, but one that exercised the processes that manipulate things in working memory: binding things together, recombining them, shifting attention to different things in working memory, and so forth. In their task, subjects watched a computer screen and every 3 seconds a square would appear in one of six positions. Simultaneously, they listened to a tape over headphones of a voice saying the names of one of six letters. The subject’s job was to monitor the square positions and the letters and to indicate when one or the other repeated. So if the subject heard C. . . P. . . P. . . T. . . R. . . T. . there was a button she was to press when she heard the second P. Simultaneously, she was to monitor the positions of the squares, and press a different button if the position of a square repeated.
If the subject could do that task without making many errors, the experimenter made it more difficult by asking the subject to respond not for simple repetitions, but when the stimulus had been the same two positions back instead of one. So in the series above, P would no longer call for a response, but the second T would. If the subject made a lot of mistakes the task reverted to the easier, one-back version, but if the subject succeed with the two-back task the experimenter increased it to 3-back! The adaptive character of the task ensures that it is always challenging, but not impossibly difficult, and also gives the task its name: the n-back task.
This task taxes working memory. Each time a new stimulus appears, the status of the letters you had been holding in working memory must be updated, you must make a new comparison, decide whether to respond, and you must do these things for both the square positions and the numbers.
Jaeggi’s subjects practiced this task for between 8 and 19 days, about 30 minutes per day.
The surprising result was that subjects improved not just on the task itself, they got better on a standard intelligence test, compared to pre-training scores on the same test. The intelligence test requires subjects to compare figures of increasing complexity and to find patterns among the features of the figures. (See here for an example.) The test (Raven’s Progressive Matrices) has multiple forms so you can give the same test more than once. A no-training control group improved a bit when taking the test a second time due to practice effects. Working memory training added a significant boost above that. Especially important was that a dose effect was observed: subjects practiced the working memory task either 8, 12, 17, or 19 days, and more practice led to greater increases in intelligence test scores.
This result is surprising because the outcome measure–the intelligence test–seems so dissimilar from the training task.
So should parents start looking for home versions of the n-back task?
That’s probably premature. There are a few important caveats to keep in mind.
First, this is just one study, and we would obviously like to see it replicated, preferably with a different profile of subject. (All of the subjects in the study were college students.)
Second, we don’t know yet whether the effects last, whether one would need to continue the training every day, or indeed, whether people would habituate to the training and training needed would increase. We just don’t know.
Third, the outcome measure–the Raven’s Progressive Matrices task–is itself supposed to be used as a predictor of behaviors we think of as important, like success with schoolwork. It would be important to see whether the training directly influences those outcomes that we really care about.
Despite these caveats, it’s an exciting first indication that there may be another way (in addition to increasing your knowledge base) to boost intelligence.
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Dan Willingham, author of Why Don’t Students Like School? A Cognitive Scientist Answers Questions About How the Mind Works and What It Means for Your Classroom, typically posts on the first and third Mondays of each month.
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