THE secret of the “eureka moment”, when a flash of inspiration suddenly resolves a tricky problem, has been explained by scientists for the first time.

The “light bulb” or “aha!” experience, in which an answer seems to appear from thin air, relies on a very different method of thinking from standard problem- solving, according to research in the United States.

Abrupt insights such as Archimedes’ discovery of water displacement, which supposedly prompted the mathematician to jump from his bath shouting “eureka”, produce a characteristic pattern of activity in a specific region of the brain’s right hemisphere, scans have shown. When people work out an answer in deliberative, methodical fashion, however, this eureka centre remains quiet, suggesting that the brain has at least two distinct ways of solving difficult problems.

Mark Jung-Beeman, of Northwestern University in Chicago, who led the study, said the results suggested that inspiration was qualitatively different from ordinary contemplation and thought.

“For thousands of years, people have said that insight feels different from more straightforward problem-solving,” he said.

“We believe this is the first research showing that distinct computational and neural mechanisms lead to these breakthrough moments.”

Edward Bowden, his colleague, said: “As supposedly happened to Archimedes, prior to solving problems with insight people often reach an impasse and are unable to make any progress. They need to reinterpret the problem and integrate information in a new way.

“Sometimes the mind does this unconsciously, and then the solution suddenly appears in consciousness. To the solver, the solution seems to have come out of thin air, yet is obviously correct.”

In the study, conducted jointly at Northwestern University and Drexel University in Philadelphia, details of which are published today in the journal Public Library of Science Biology, Dr Jung-Beeman and Dr Bowden asked volunteers to solve a series of word problems. Participants were given a series of three words, such as “fence”, “card” and “master”, and told to think of a single word that would go with each to form a compound word. The answer in this example is “post” — “fencepost”, “postcard”, “postmaster”.

The problems were designed so that most people would solve them methodically and by insight about half of the time each. The volunteers’ brains were scanned using functional magnetic resonance imaging (fMRI) as they solved the problems. When the subjects reported having an “aha! moment”, a region of the brain known as the anterior superior temporal gyrus, in the right temporal lobe, tended to fire with activity. When they solved the problems through methodical working, that region was inactive.

The anterior superior temporal gyrus is thought to play a critical part in pulling together distantly related information, and may be activated subconsciously to produce sudden insights when all the pieces fall into place.

A second experiment, which used an electroencephalogram (EEG), measured brainwave activity as subjects solved the problems.

About a third of a second before a problem was solved with insight, there was a sudden burst of high-frequency activity. This appears to mark the moment of inspiration.

Howard Gardner, Professor of Education and Cognition at Harvard University, said: “If there is one human trait that would seem impervious to scientific study, it is intuition or insight — that seemingly nonrational ‘aha!’ that accompanies sudden recognition or solution.

“In showing that distinctive cortical activity characterizes self reports of insight, while being absent on solutions bereft of insight, Jung-Beeman and his colleagues have helped to demystify the creative process.”

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