From the New York Times Magazine:
By Dan Hurley
Since the first reliable intelligence test was created just over a hundred years ago, researchers have searched for a way to increase scores meaningfully, with little success. The track record was so dismal that by 2002, when Jaeggi and her research partner (and now her husband), Martin Buschkuehl, came across a study claiming to have done so, they simply didn’t believe it.
The study, by a Swedish neuroscientist named Torkel Klingberg, involved just 14 children, all with A.D.H.D. Half participated in computerized tasks designed to strengthen their working memory, while the other half played less challenging computer games. After just five weeks, Klingberg found that those who played the working-memory games fidgeted less and moved about less. More remarkable, they also scored higher on one of the single best measures of fluid intelligence, the Raven’s Progressive Matrices. Improvement in working memory, in other words, transferred to improvement on a task the children weren’t training for.
Even if the sample was small, the results were provocative (three years later Klingberg replicated most of the results in a group of 50 children), because matrices are considered the gold standard of fluid-intelligence tests. Anyone who has taken an intelligence test has seen matrices like those used in the Raven’s: three rows, with three graphic items in each row, made up of squares, circles, dots or the like. Do the squares get larger as they move from left to right? Do the circles inside the squares fill in, changing from white to gray to black, as they go downward? One of the nine items is missing from the matrix, and the challenge is to find the underlying patterns — up, down and across — from six possible choices. Initially the solutions are readily apparent to most people, but they get progressively harder to discern. By the end of the test, most test takers are baffled.
If measuring intelligence through matrices seems arbitrary, consider how central pattern recognition is to success in life. If you’re going to find buried treasure in baseball statistics to give your team an edge by signing players unappreciated by others, you’d better be good at matrices. If you want to exploit cycles in the stock market, or find a legal precedent in 10 cases, or for that matter, if you need to suss out a woolly mammoth’s nature to trap, kill and eat it — you’re essentially using the same cognitive skills tested by matrices.
I tend to look at this from the opposite perspective: Can you let your intelligence deteriorate? Yes, probably, I would imagine.
It's a little like the perennial question debated by stat nerds of whether or not athletes enjoy hot streaks. They certainly suffer cold streaks when they are marginally injured, suffering from illness, worried that their wives will divorce them, angry at their teammates, defended by outstanding players, fallen into bad mechanics, etc. Perhaps hot streaks are just the absence of all cold streaks?
Anyway, I can well imagine that not exercising your brain could lead to declines in intelligence.
But, then, the question becomes what is the best brain exercise for you individually. Is it one of these abstract games that are kind of like a Ravens Matrices IQ test? Or maybe, say, reading, oh, I don't know, this blog is good exercise for your brain. Plus, it's fun and informative.
As they say at the end of scientific papers, more research is needed!