A new study shows that measuring changes in the stomach may be better at spotting a lie than standard polygraph methods.
Polygraphs use electrocardiograms (ECGs) to measure changes in heart rate and sweating to detect lies. But researchers say the stomach and gastrointestinal tract are also extremely sensitive to stress, and this mind-stomach connection may betray even the best liars.
Their results suggest that adding gastrointestinal monitoring to standard polygraph techniques may increase the accuracy of lie-detection methods, which are about 90% accurate.
Stomach as Lie Detector?
In the study, researchers measured changes in the stomach using an electrogastrogram (EGG) in 16 healthy volunteers while they did nothing, told the truth, or told a lie. The participants also had a simultaneous ECG to measure changes in heart rate. An ECG records electrical signals of the heart muscle; an EGG records electrical signals of the muscles of the stomach.
Researchers presented their results this week at the annual meeting of the American College of Gastroenterology in Honolulu.
The study showed that both lying and telling the truth were associated with changes in heart rate and stomach activity. The act of lying was associated with a decrease in the amount of normal gastric "slow waves."
"The addition of the EGG to standard polygraph methods has clear value in improving the accuracy of current lie detectors," says researcher Pankaj Pasricha, MD, of the University of Texas Medical Branch, in the news release. "The communication between the big brain and the little brain in the stomach can be complex and merits further study."
Sources: Annual meeting of American College of Gastroenterology, Honolulu, Oct. 29-30, 2005. News release, American College of Gastroenterology.
By Jennifer Warner
Reviewed by Louise Chang, MD
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