Lying and digestive changes

By HSC Staff Writer • Published: February 22nd, 2006
Category: Health in a Heartbeat

Even the most honest among us practice a bit of deception at some point in our lives. For example, you tell a friend, “Your outfit looks great,” when you really think it looks terrible.

But, perhaps for a job or other reason, you may have to take a lie detector or polygraph test. Of course, this test can’t tell if you are lying… only that you indicate deceptive behavior.

Lie detectors compare readings from heart rate, respiratory rate and skin sweating under stress to normal levels. Variations may signal a person is deceptive. However, polygraph results are often criticized as inaccurate.

But a new twist may be given to the old lie detector test: measuring changes in the digestive tract. Researchers from the University of Texas Medical Branch in Galveston recently showed distinct changes in the digestive tract when a person lies. Sixteen volunteers were hooked up to an electrogastrogram, a machine that works like an E-K-G. The scientists recorded electrical signals that travel through the muscles of the stomach. In this painless procedure, electrodes are taped over the stomach, and the person is asked questions. When the subject lies, waves in the digestive tract decrease. Surprisingly, lying had a closer correlation with stomach changes than with heart changes.

Combining the stomach test with the polygraph may lead to better lie detection in the future. However, researchers warned that these volunteers weren’t trained in deception. So the truth is, really good liars just might learn to control their stomach movements.