Eureka! The brain science behind lightbulb moments

Experiences of insight come with a burst of brain activity — and a memory boost

Mindia Wichert has taken part in plenty of brain experiments as a cognitive-neuroscience graduate student at the Humboldt University of Berlin, but none was as challenging as one he faced in 2023. Inside a stark white room, he stared at a flickering screen that flashed a different image every 10 seconds. His task was to determine what familiar object appeared in each image. But, at least at first, the images looked like nothing more than a jumble of black and white patches.

“I’m very competitive with myself,” says Wichert. “I felt really frustrated.”

Cognitive neuroscientist Maxi Becker, now at Duke University in Durham, North Carolina, chose the images in an attempt to spark a fleeting mental phenomenon that people often experience but can’t control or fully explain. Study participants puzzling out what is depicted in the images — known as Mooney images, after a researcher who published a set of them in the 1950s¹ — can’t rely on analytical thinking. Instead, the answer must arrive all at once, like a flash of lightning in the dark (take Nature’s Mooney-images quiz below).

Becker asked some of the participants to view the images while lying inside a functional magnetic resonance imaging (fMRI) scanner, so she could track tiny shifts in blood flow corresponding to brain activity. She hoped to determine which regions produce ‘aha!’ moments.

Over the past two decades, scientists studying such moments of insight — also known as eureka moments — have used the tools of neuroscience to reveal which regions of the brain are active and how they interact when discovery strikes. They’ve refined the puzzles they use to trigger insight and the measurements they take, in an attempt to turn a self-reported, subjective experience into something that can be documented and rigorously studied. This foundational work has led to new questions, including why some people are more insightful than others, what mental states could encourage insight and how insight might boost memory.

Becker’s study aimed to find out how the rapid reorganization and integration of knowledge that she and others think is a defining feature of insight happens in the brain and whether it’s linked to memory². Through such work, researchers could better explore memory and learning more generally, and perhaps find ways to enhance both.

“We are at this extremely exciting verge, where we can get closer to insight than we have ever come before,” says Becker.

Capturing the flash

Whereas analytical thinking involves using logic and reasoning to arrive at a solution in a step-by-step way, insight is a sudden realization that seems to pop into conscious awareness. These mental leaps can lead to a grand discovery or solution, or something more mundane — the answer to a daily word puzzle, for example.

Throughout the twentieth century, cognitive psychologists wrestled with how to distinguish insight from analytical problem solving. Although consensus was growing that insight was distinct, not everyone agreed. Cognitive psychologist Robert Weisberg at Temple University in Philadelphia, Pennsylvania, has argued, for example, that insight might not be as different from analytical thinking as it seems. He has suggested that insight, too, comes from the brain gradually building on what it already knows — incorporating new information with each failed attempt. For him, the main feature of insight is the emotion that someone feels after finding an answer or creating something that seems new.

“It’s true that we get aha! experiences,” says Weisberg. “But that doesn’t mean the underlying process is different. It just means the outcome knocks your socks off.”

Cognitive neuroscientist John Kounios, who began studying insight in the 1990s at Tufts University in Medford, Massachusetts, has a different view. For him, insight isn’t about adding up knowledge to arrive at an answer. Instead, it’s when a person spontaneously forms new knowledge. Sometimes, says Kounios, now at Drexel University in Philadelphia, “it’s the solution to a problem they didn’t even know they had”.

Most early insight research was based on self-reports alone. Kounios decided to bring a different type of data into the field. In the early 2000s, he began using technologies including fMRI and electroencephalogram (EEG) — which captures electrical activity — to look for a distinct signature of insight in the brain. “We were prepared to be proven wrong,” he says.

In the laboratory, he and cognitive neuroscientist Mark Beeman at Northwestern University in Evanston, Illinois, used what are known as remote associate problems to trigger aha! moments. Participants were tasked with finding a word that connects three seemingly unconnected ones, such as ‘home’, ‘sea’ and ‘bed’. (The answer is ‘sick’.) After each attempt, they reported whether the solution came with an aha! feeling. If so, they rated the strength of the feeling. Kounios and Beeman used fMRI scans and EEGs to monitor participants’ brains as they solved the puzzles.

In their early experiments³, Kounios, Beeman and their colleagues found that insight was accompanied by a burst of activity and blood-flow changes in the right side of the brain, in a region called the right superior temporal gyrus, which is associated with learning, memory and language processing. This activity occurred just 300 milliseconds before participants pressed a button to report being consciously aware of the answer. Kounios and Beeman had detected an aha! signal in the brain.

The pair also found that neural activation linked to insight is more sudden and localized than that for analytical problem-solving, supporting the notion that insight is an abrupt realization of knowledge rather than a gradual accumulation.

Further studies have shown that insight consistently includes a burst of high-frequency gamma waves that can involve different areas of the brain. Another common region of activity is the anterior cingulate cortex, which is involved in attention, emotion and decision-making.

Kounios, Beeman and others have done “really rigorous research” to demonstrate how insight is grounded in brain activity, says cognitive psychologist Daniel Schacter at Harvard University in Cambridge, Massachusetts, adding that such work will improve our understanding of other forms of creative cognition.

In 2020, cognitive neuroscientist Carola Salvi at John Cabot University in Rome reported another line of evidence supporting the idea that insight and analytical problem-solving are distinct processes. In an experiment with 38 participants, Salvi discovered that people’s pupils rapidly dilated about 500 milliseconds before they reported having an insight — signalling a shift in awareness⁴. When participants solved problems analytically, their eyes instead made tiny, rapid movements known as microsaccades.

Early cognitive psychologists who described insight as a distinct process were onto something, says Salvi. “A hundred years later, we were finally able to say they were right,” she says.

Memory follows insight

Salvi thinks that pupil dilation reflects a shift in cognitive processing linked to activity in a brain network involved in regulating attention and arousal, which might also influence memory formation.

A link to memory would make sense, Salvi says. Psychologists have observed that people tend to better remember moments of their lives marked by strong emotions. “That’s why you can remember a lot of details of events like your first date or your wedding,” says Salvi.

For the past decade, cognitive psychologist Amory Danek at the Technical University of Munich, Germany, has been studying whether such a memory boost also comes with the emotional experience of insight.

She decided to move away from the three-word puzzles that other researchers had been using. She suggests that these stimuli lack an element present in real-world aha! moments: an initial false representation that forced people to restructure the problem to solve it. “They were quite boring,” says Danek. “I was not satisfied with that.”

Instead, Danek decided to collaborate with a professional magician for her experiments. After showing study participants videos of a magician performing tricks, she asks the participants to attempt to work out how the tricks were done. Participants come up with a solution and report whether they arrived at it through insight. “Magicians put the observers in the wrong mental set before they do a trick,” says Danek. “Observers have to break free from this initial wrong problem representation in order to understand how it’s done.”

Danek also thought magic tricks would elicit more intense emotions, which people easily recognize and can thus reliably report. She asks study participants reporting a solution to rate on a scale from 0 to 100 their feelings of suddenness, certainty and pleasure, for example.

In one experiment, participants tried to remember the solutions two weeks after watching the tricks⁵. Danek found that people who reported discovering how a magic trick was achieved through insight were better able to remember the solution than were those who didn’t experience insight. She calls this memory boost the “insight memory advantage”⁶.

Cognitive neuroscientist Roberto Cabeza at Duke University says that insight often comes with mental processes related to memory, such as semantic learning — when people find that solutions align well with what they already know — and emotional memory, which strengthens recall through emotional engagement.

Other research hints that people are better at remembering unrelated, random information that they encounter around the time of aha! moments, as well as ‘d’oh!’ moments, when a solution is revealed and suddenly feels obvious⁷.