Liar, liar, guts on fire
An erratic gut could give away a cunning liar as much as his or her rapid heartbeat, says a US study.
The key lies in the stomach's sensitivity to the mental stress of lying because the gut's nervous system is linked to the central nervous system and the brain, the researchers say.
In a presentation at an American College of Gastroenterology scientific meeting this week, researchers described how they hooked 16 participants up to electrogastrograms (EGG) and electrocardiograms (ECG) simultaneously, and measured gut and heart activity.
The University of Texas researchers found that both lying and telling the truth affected the heart rate, while lying was also associated with gastric activity.
The EGG showed a significant decrease in gastric activity when the participant was lying that corresponded to a significant increase in the average heart rate under the same conditions.
The researchers say adding EGGs to standard polygraph methods, which measure other involuntary physiological activities like pulse rate and perspiration, could improve the accuracy of lie detection procedures.
But president of the Gut Foundation, Australian gastroenterologist Associate Professor Terry Bolin, is not so sure.
While doctors have long known there was a neurological link between the brain and the gut, he says a relationship between the gut and lie detection is open to question.
"The researchers seem to be able to distinguish between lying and not lying. But if you had an EGG attached to you, you might be tense and anxious anyway. There are also brain mechanisms that can override gut activity. Many people describe a slowing of heart rate and more tranquillity in their gut with meditation, for example," he says.
"I can't see that there is much application for this test. Lie detectors in Australia aren't admissible as evidence and a lot more work would be required to clearly establish that the EGG is a more reliable indicator of lying than anything else."