In the second experiment, an electroencephalogram (EEG) tracked brainwave activity during insight and non-insight solutions. About one-third of a second before the subjects indicated solutions achieved through insight, there was a sudden burst of high-frequency (gamma band) activity, relative to solutions achieved without insight. This neural activity, often associated with complex cognitive processing, was observed at scalp electrodes over the same right temporal area observed with fMRI, replicating the effect with new participants and a different measure of brain activity.
A second, unexpected EEG effect also was observed: About 1.5 seconds prior to insight solutions, an increase in lower frequency (alpha band) activity appeared over the right posterior cortex. This effect disappeared precisely when the high-frequency activity began over the right temporal lobe. The researchers interpreted the posterior effect as evidence of "gating," or attenuation, of visual input, and suggested that this occurs to allow initially weak solution-related activity to gain strength, then burst into consciousness as an insight.
"This is like closing your eyes so you can concentrate when you are trying to solve a difficult problem," said Kounios, professor of psychology at Drexel. "But in this case, your brain is blocking out just the visual inputs to your right hemisphere."
Success in solving insight problems is associated with creative thinking. "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," said Howard Gardner, Hobbs Professor of Education and Cognition at the Harvard Graduate School of Education, who was not involved in the study. "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 helpe
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Contact: Megan Fellman
fellman@northwestern.edu
847-491-3115
Northwestern University
13-Apr-2004