Detective Slick sidled up to Johnnie Ray, who sat smugly in his small wooden chair, looking into the one-way mirror, picking the remnants of chicken chow fun out from his yellow teeth.
"I'm going to ask you this once, Johnnie," Slick said. "Did you strangle Gertrude Muller?"
Johnnie Ray, whose ability to wring the necks of little old ladies was only surpassed by his knack for maintaining his heart rate during questioning, smiled and looked the detective in the eye.
"No, Slick. I did not kill poor Mrs. Muller."
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Immediately alarms sounded throughout the the station. Now it was Slick's turn to look smug as he clasped the cuffs on a bewildered Johnnie Ray.
"Your eyes said 'No,' Johnnie," Slick told him. "Your heart said 'No.' Your glands said 'No.' But your stomach, Johnnie Ray? Your stomach said, 'Yeah, I killed that lady.' And now you're going to pay for it, Johnnie. You are going to pay dearly."
The characters are fictional, but the possibility is real. According to a new study out of the University of Texas (UT), changes in the stomach's pulse can signal the stress associated with lying—and can do so better than changes in a person's heartbeat.
If the head researcher were to try to talk her way into a bar or even a voting booth, her stomach would go haywire. Trisha Pasricha, who conceived of the study and used her father's lab equipment to carry it out, is just a junior at Clear Lake High School in Houston.
In her experiment, Trisha gave each of her 16 subjects a playing card, which each subject looked at privately. She then showed the subject projections of cards, each time asking, "Is this your card?" The subject was only to lie if the card on the screen was the one in their hand. Trisha, however, had an ace up her sleeve: She controlled the conditions so every subject told the truth twice and lied twice. Subjects were offered $20 if they could trick the electrogastrogram, a machine that monitors electric pulses in the stomach via external leads attached to the skin.
Not a single subject tricked the machine. The machine showed a substantial disruption in the normal stomach pulse when subjects lied about their cards.
And what—didn't you not know that the stomach has a pulse? According to UT gastroenterologist and proud father P. Jay Pasricha, the gastrointestinal system has the workings of an entire brain spread out between muscle layers.
"The gut's brain is probably, from an evolutionary perspective, older than the brain inside our head and it's just as complex as the other nervous system," he said.
Pasricha said this nervous system is generally independent from the central nervous system, but the two systems do communicate, giving people the lovely sensations of queasiness and nausea. The gastrointestinal nervous system works as a pacemaker for the stomach and intestines, keeping the stomach running at three cycles per minute, he said. When a person is under stress, the stomach departs from its normal cycle.
Right now polygraphs have an accuracy of about 90%. While Trisha and her father freely admit that their study was only preliminary, they believe stomach monitoring will improve upon existing polygraphs.
"Countermeasures a subject can take to avoid detection such as regulating breathing patterns or putting anit-perspirant on the fingers...will be more difficult to do with the electrical activity in the stomach," Trisha said via e-mail.
She also said that the equipment needed to monitor the stomach only costs about $5,000, much less than the several million-dollar price tag on an fMRI machine, which scientists currently hope will act as an improved polygraph.