"Gut Reaction" is much more than just a colorful and imprecise expression. It is a very real and measurable physiological phenomenon connected to our brain ... and now it appears, also to our conscience. Researchers at the American College of Gastroenterology conference recently presented a paper showing that compared to the standard polygraph which measures the heart rate, an "electrogastrogram", which monitors changes in the gastrointestinal tract, is a more accurate indicator of one's truthfulness. But the wrinkle here is that just as with the polygraph, a very accomplished liar (or a sociopath) could conceivably bluff the "gut check" machine.
"When a person is lying, distinctive changes occur in the digestive tract, researchers have determined. The standard polygraph test, often criticized as inaccurate, may be improved if it is combined with a test for the stomach changes, they say.
One author of the study, Dr. Pankaj J. Pasricha of the University of Texas Medical Branch at Galveston, said the test for changes in the gastrointestinal tract, an electrogastrogram, was painless and simple to perform. It measures activity in the digestive tract.
"We expected to see an effect because we know that stress does affect GI function," Dr. Pasricha said.
But when 16 volunteers were hooked up to heart and digestive tract monitors, the researchers were surprised to find that lying had a closer correlation with stomach changes than with heart changes.
When the subjects lied, their heart rates increased, but it also did so at other times. On the other hand, lying was consistently associated with a decrease in the slow waves of the digestive tract."
The report does not indicate if gut reaction to lying could be either masked or enhanced by the kind of food one ate before testing - say a bland "soup & salad", as opposed to a fiery Mexican or Indian meal. If research can establish a correlation between the choice of food and accuracy of lie detection, it might give rise to a whole new practice in crime investigation - "The First Meal". Only, in this case, the prosecutor and the detectives, not the suspect, would pick the menu.
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