A new study by medical researchers at the University of Texas suggests that a new type of polygraph test could be on the way, focusing not on how the heart responds to lying and telling the truth but on how the stomach reacts. 

 

The results of the study were announced on Monday at the 70th Annual Scientific Meeting of the American College of Gastroenterology, in Honolulu.

 

The term “polygraph” literally means “many writings” and refers to simultaneous recordings of multiple physiological activities. Current lie detector tests monitor changes in heart rate and sweating, but are only about 90 percent accurate, according to the researchers. 

 

The American Polygraph Association points to several studies that place polygraph accuracy between 81 and 98 percent. 

 

In the new study, the researchers took 16 healthy volunteers and recorded both contractions of the heart muscle, an electrocardiogram; and the wave-like contractions of the stomach, an electrogastrogram. 

 
 

They found that both lying and telling the truth affected the activity of the heart, but only lying was significantly associated with stomach symptoms, causing a decrease in the percentage of normal gastric slow waves.

 

“Standard polygraph methods to assess heart rate variability may not perform as well as the electrogastrogram in distinguishing between lying and telling the truth,” said the study brief.

 

More Research Required

More research with larger sample sizes and real-life situations will be required before the findings can be considered for standard lie detection methods. 

 

“We concluded that the addition of the electrogastrogram to standard polygraph methods has clear value in improving the accuracy of current lie detectors,” said Pankaj Pasricha, one of the researchers involved in the study.

A new study suggests that changes in gastric physiology perform better than standard polygraph methods in distinguishing between lying and telling the truth. The University of Texas study, released today at the 70th Annual Scientific Meeting of the American College of Gastroenterology, demonstrates a clear link between the act of lying and a significant increase in gastric arrhythmia.

To test their hypothesis that the gastrointestinal tract is uniquely sensitive to mental stress because of the communication between the central nervous system and the enteric nervous system, researchers at the University of Texas Medical Branch recruited sixteen healthy volunteers to undergo simultaneous electrogastrogram (EGG) and electrocardiogram (EKG) recordings for three periods.

The researchers found that both lying and truth telling affected cardiac symptoms, while the act of lying was also associated with gastric symptoms. The EGG showed a significant decrease in the percentage of normal gastric slow waves when the subject was lying that corresponded to a significant increase in the average heart rate during the same situation.

"We concluded that the addition of the EGG to standard polygraph methods has clear value in improving the accuracy of current lie detectors," said Pankaj Pasricha, MD, University of Texas Medical Branch. "The communication between the big brain and the little brain in the stomach can be complex and merits further study." 

Liars could be caught out by the reaction of their stomachs to telling untruths, suggests preliminary research from the University of Texas, US. The team believe that the early-stage technique could one day improve the accuracy of polygraph tests, which rely mostly on monitoring heart activity.

“The heart is unreliable because it’s affected by not only by your brain, but by many other factors, such as hormones,” says Pankaj Pasricha, who is leading the team. “The gut has a mind of its own – literally. It has its own well-developed nervous system that acts independently of almost everything except your unconscious brain.”

The test uses a device called an electrogastrogram (EGG) to determine when a person’s stomach “beats” speed up from the typical three per minute. Whereas heart beats can increase whether a person is lying or telling the truth, the group’s initial findings from 16 test subjects reveal that the stomach’s rate typically does not increase if a person is telling the truth, however nervous they may be.

“This might very well be the case,” says Kevin Murphy, a psychologist at Penn State University, Pennsylvania, US, who recently headed a panel for the US National Academy of Sciences to analyse the science behind polygraph devices. “But polygraph detectors, whatever their ilk, measure stress and not lying. This new test might give more, potentially very useful, data."