Most of us have had the experience of struggling mightily to solve a problem only to find, while taking a walk or doing the dishes, that the answer comes to us seemingly from nowhere. Psychologists call these sudden aha! moments “insight.” They occur not only when we are faced with a problem but also when we suddenly “get” a joke or crossword puzzle clue or are jolted by a personal realization. Scientists have identified distinctive brain activity patterns that signal moments of insight, but there is still some debate about whether insight is simply the final, most satisfying step in a deliberative thought process or a wholly separate form of thinking.

An ingenious new study by a team of Belgian psychologists provides additional evidence that insight engages unconscious mechanisms that differ from analytic, step-by-step reasoning. Even when people are managing multiple demands on their brainpower, the research suggests their intuitive thought processes may still be readily accessible.

“You can be overloaded by all this type of stuff, cell phones or whatever, and your insights remain shielded,” says Hans Stuyck, a doctoral student at Université Libre de Bruxelles and KU Leuven in Belgium, who led the study.

For that investigation, which was first published online in December 2021 in the journal Cognition, the psychologists created 70 word puzzles that undergraduate students could solve using either insight or analytic reasoning. Each puzzle consisted of three Dutch words displayed on a computer screen. The task was to find a fourth word that pairs with each. (For example, if the test were conducted in English, people might be given the words “artist,” “hatch” and “route,” with the answer being “escape” because “escape artist,” “escape hatch” and “escape route” are all recognizable phrases.)

The 105 undergraduates, most of whom were women, had up to 25 seconds to solve each problem. After typing an answer, they indicated whether they had reached it “with Aha!”—which they were told meant becoming “aware of the solution suddenly and clearly,” like a lightbulb illuminating a dark room—or calculated it step-by-step “without Aha!”—as if their brain was a room slowly being lit with a dimmer switch.

Participants were divided into three groups. The first received only the puzzles. In the second group, two random digits flashed sequentially on the screen before the words appeared, and people had to try to recall those numbers after finishing the puzzle. The third group was identical to the second except that people had to try to remember four digits instead of two.

The purpose of making people remember random numbers was to burden their mind with an unrelated task, which was expected to interfere with conscious problem-solving. “These cognitive resources, this pool that we can tap into to do anything consciously, is limited,” Stuyck says. The question was whether insightful thinking would be similarly affected.

Indeed, when participants used analytical thinking—by, for example, generating a phrase such as “con artist,” checking whether “con” was a match with “hatch” or “route” and then moving on—they experienced diminishing returns, solving, on average, 16 puzzles when they had no numbers to remember but only 12 puzzles when they had to remember two digits and eight puzzles when they had to remember four.

Yet when people relied on insight, not only was their success rate higher, it was unaffected by the number-recall task. These participants accurately completed between 17 and 19 puzzles, on average, in all three groups. “Whether they don’t have the memory task or they have a low-demand memory task or a high-demand memory task, the number of puzzles they solve with insight remains constant,” Stuyck says. “That’s the most interesting result.”

A significant amount of brain activity is unconscious—that is why we can seemingly drive to work automatically and why we are not always aware of the biases that affect our decisions. But cognitive psychologists disagree about whether actual reasoning can occur below the level of awareness. “There is so much debate within the literature,” Stuyck says.

Stuyck believes that during moments of insight, there is a give-and-take between conscious and unconscious processes. For example, when people attempt the puzzle “pine/crab/sauce,” multiple word associations get activated but only the strongest are accessible to the conscious mind. If the correct answer happens to be a weaker association, people may feel stuck, he says, yet beneath the surface, unbeknownst to them, their mind may be ushering it into awareness. (The answer, by the way, is “apple.”)

“Trying to find a creative solution to a problem is like trying to see a dim star at night,” says Mark Beeman, a cognitive neuroscientist at Northwestern University and a leading expert on insight, who did not contribute to the new study. “You have to kind of look at it out of the corner of your mind.”

Insights typically occur after someone ponders a problem for a while and then puts it aside, Beeman says. Once the foundation has been laid through conscious mental effort, a stroll, nap or distracting task seems to enable a creative breakthrough, one that is typically accompanied by feelings of satisfaction and certainty.

The reason that holding two or four numbers in one’s head slows reasoning but does not affect insight-based problem-solving is because turning the spotlight on a faint idea does not seem to require mental exertion, Stuyck says.

Beeman agrees but cautions against directly extrapolating from the new study to the real world. The number-recall task may have been simple enough to serve as a useful diversion, helping puzzlers reach their eureka moment. He doubts the results would hold if people’s brainpower was more severely taxed. “I certainly don’t want to recommend that people who want to be more creative at work get saddled with more work,” he says.

Stuyck’s team is about to embark on another puzzle-based insight experiment. This time the researchers will create “virtual lesions” by temporarily deactivating part of the prefrontal cortex, the brain area that we engage to consciously manipulate information. (They will use a harmless, noninvasive method called transcranial magnetic stimulation, which stimulates brain cells using magnetic fields.) This transient impairment is expected to diminish people’s success when they use an analytic approach to puzzling, but the question is whether it will affect their ability to solve problems through insight.