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Gastric lie-detectors: Can liars stomach this?
Tony Tharakan in New Delhi | November 17, 2005 12:32 IST
They say the way to a man's heart is through his stomach. And if Indian-American scientist Pankaj Pasricha has his way, one could also use a man's stomach to know if he's lying.
A researcher at the University of Texas Medical Branch of Galveston, Pasricha came up with the idea of measuring electrical impulses in the gastrointestinal tract to find out if the subject was lying.
The idea struck Pasricha while helping his daughter Trisha with a high-school project, leading him to experiment with the 'electrogastrogram' to measure electrical impulses in the stomach-- a procedure already in clinical use to diagnose certain stomach ailments.
Sixteen volunteers were hooked up simultaneously to the traditional heart monitor and the digestive tract monitors.
Pasricha and his colleagues found that lying had a closer correlation with stomach changes than in the standard polygraph test.
"The theory is that lying produces stress which results in signaling from the brain to other parts of the body including the stomach and heart.
In our study, both lying and telling the truth accelerated the heart rate. However, the stomach rhythm was only affected by lying. Potentially therefore, this is more accurate or specific," Pasricha told PTI in an email interview.
The problem has been that any kind of stress can produce changes in heart rate including the stress from simply being subjected to a polygraph-- a factor which makes evidence from lie-detector tests for police investigations legally unacceptable.
Pasricha presented his findings at an American College of Gastroenterology conference in Hawaii last week, but admits more research is needed before the 'electrogastrogram' can be used for detecting lies.
"While clearly this would be valuable, the study that we did was a small pilot trial and we need to do more. If confirmed, this will certainly add to the field. Further research is needed in real-life situations," Pasricha said.
Experts believe that conventional polygraph tests are accurate 80 to 90 per cent of the time. The problem arises when innocent people anxious about being tested fail the test or the guilty learn to beat the machine.
According to Pasricha, the standard polygraph test may use the stomach technique to come up with much more accurate results. However, Pasricha admits that the system is not yet perfect and that hardened criminals or even really good liars may be able to control some of the body's automatic responses.
"Nothing is ever foolproof. The more parameters you add to the polygraph, the better the test will be. It is may be more difficult to control the gastric nervous system voluntarily than breathing or heart rate but this is speculative. Perhaps some yogis could do it," he says.
The answer can only lie in further research, which would require funds, something Pasricha is eagerly looking out for.
"We don't have a grant since this was a side project for us. But the university has applied for a patent on this," he says.