# Eureka! How the Brain has 'Aha' Moments

Think of one word that can form a compound word with "sauce," "pine" and "crab."

I'll wait . . . .

Time's up: did you come up with "apple," to make "applesauce," "pineapple" and "crabapple"? OK, let's consider that a warmup. Try the same exercise—finding a word to make a compound word—with "bump," "step" and "egg."

One more: for "back" "clip" and "wall." . . . .It's "paper," for "paperback," "paperclip" and "wallpaper."

If you're like many people, you tried to solve each problem methodically, first finding a word that would go with, say, "sauce" and then trying it out with "pine" and "crab." But if you're like most people in a more important way, if you solved these brain-teasers you did so not through this grind-through-the-possibilities approach, but through insight. That is, you thought a little and then, wham, the answer suddenly hit you.

Scientists have approximately no idea how this happens.

But they're trying to figure it out, partly because some of the more notable achievements in, especially, science and math came to their discoverers through such "eureka" moments—Archimedes' law of buoyancy and Newton's theory of gravity, for instance. ("Eureka" is in fact what Archimedes yelled when he leapt out of his bathtub upon figuring out how to calculate the volume of an irregularly shaped object: measure how much water it displaces.)

In each case, the moment of genius was preceded by two things, First came a mental impasse ("I'm stuck and have no idea what the &^\$*ing answer is!"). Then came a restructuring of the problem ("OK, I must be thinking about this all wrong") that leads to deeper understanding. Finally, you suddenly see the answer—which, in retrospect, seems blindingly obvious. In the most far-reaching study conducted so far on what the brain is doing before achieving an "aha" moment, two scientists used EEGs (electroencephalograms) to determine the site and type of brain activity during the stages leading up to the sense of eureka as well as the eureka moment itself.

They gave volunteers those sauce/pine/crab kind of word problems while electrodes monitored their brain activity. Sure enough, the volunteers reported being at a mental impasse at first. But those who eventually solved the problem also reported restructuring (moving from an inappropriate way of thinking about the problem and not knowing how to proceed to a state of knowing how to solve it). That is made possible by what the scientists call "internal retrieval processes," which search your memory for ideas that can be used to reinterpret your knowledge (for instance, don't think only of words that come before the given ones).

As Joydeep Bhattacharya of Goldsmiths College, London, and Simone Sandkuhler of the Medical College of Vienna report in their new study, being published in the open-access journal PLoS ONE tomorrow, mental impasse was characterized by excessive gamma waves. This brain rhythm is enhanced with focused attention; simply put, the would-be problem solvers were thinking too hard about one specific thing.

But those who successfully solved the puzzles, sometimes after the scientists gave them a hint, seemed to let their thoughts run free, rather than overthinking either the problem or their own thought processes. That suggests that success depends on an unconscious restructuring of information, as volunteers let their brains reshuffle words almost randomly until they came up with the answer.

Solving these word problems may not be precisely akin to, say, Archimedes' eureka moment, but it's not exactly feasible to scan the brains of everyone trying to solve a real-world problem to see what brain activity precedes the moment of insight. And in fact, these new results fit with the little work that has been done to date on the brain mechanisms underlying insight.

In 2004, for instance, Bhavin Sheth of the University of Houston measured the brain waves of people trying to solve problems like this: moving as few sticks as possible, turn the incorrect Roman-numeral equation XI + I = X (11 + 1 = 10, for those who forgot Roman numerology), made out of matchsticks, into a correct one. Some people try to solve it, Sheth told the 2004 meeting of the Society for Neuroscience, in a plodding, uncreative, trial-and-error way, usually moving the matchstick that makes up XI on the left to get X + I = XI. But if you mentally rotate the equation (or turn the paper it's written on upside down, as Sheth's volunteers could do), XI + I = X becomes X = I + IX (10 = 1 + 9) without moving a single stick.

In people who found the creative, zero-stick solution, low-frequency brain waves known as delta and gamma dropped just before the eureka moment. Delta waves are characteristic of such mental processes as memory; gamma waves, of coordinated mental activity. Both seem to mark focused, but conventional, mental activity. The fact that both disappeared right before the eureka moment suggests that the brain was escaping from conventional thought patterns, just as the latest study also found.

Right before the eureka moment, but not before the unimaginative solution, theta waves in the front of the brain increased. Theta waves seem to encode new information, so this suggests that people were forming new associations between previously unconnected concepts, or seeing the information in the problem in a new light. Specifically, they mentally rotate the matchsticks, coming up with a spatial solution to a numerical problem.

An earlier study that used the sauce/pine/crab type of problem reinforces this idea. When psychologist Mark Jung-Beeman of Northwestern University asked volunteers to find one word that could form a compound word with all three of the given words, he and colleagues found in a 2004 study that some people solved the problem uncreatively, thinking of every word that goes with "crab" and then trying them all on "pine," for example. But volunteers who got it through insight rather than drudgery said they just stared at the words until "apple" popped into their head. Right before this insight, there was a spike in activity in the brain's anterior cingulated, which reorients attention. That reinforces the idea that insight requires directing the brain away from the dead ends that characterize mental impasses.

So if you're stuck on a problem that requires creativity, the first thing to do is relax, mentally. Stop pursuing the same old dead ends. Let your thoughts wander. Let your attention flit between seemingly irrelevant memories and thoughts. That's the best way to let disparate pieces of the puzzle come together into your own eureka moment.