US scientists believe they may be able to develop a more reliable lie-detector test - by listening to liarsâ€™ stomachs.
Until now, conventional polygraph tests, which are 80 to 90% accurate, have been used. They note such changes as increased heart rates and sweating.
However people who are speaking the truth can show similar changes merely because they are anxious about being tested.
So, the University of Texas study involving 16 people has found that looking for gut pattern changes is a more reliable test.
Dr Pankaj Pasricha and colleagues told an annual meeting of the American College of Gastroenterology how their test, called an electrogastrograrn (EGG), could clearly spot when someone was telling a fib. They asked 16 volunteers to simultaneously undergo EGG tests and standard electrocardiogram (ECG) - a test to measure heart rate, which makes up part of standard polygraph testing.
Like the conventional polygraph test, an EGG is recorded by attaching painless electrode stickers to the skin .
The researchers found that both lying and telling the truth affected the EGG recordings compared to baseline measurements when the volunteers were asked simply to rest.
In comparison, the EGG showed obvious changes only when the individual was telling a lie - there was a big decrease in the percentage of normal gastric slow waves. â€œFurther research in real-life situations and using larger numbers is necessary to validate these results,â€ cautioned the authors.
Professor Richard Wiseman, a psychologist at the University of Hertfordshire, said: â€œIt is an interesting idea. â€œHowever, like the conventional lie detector, the technique seems to rely on the notion that people become more stressed when they lie. People who do not feel guilty about lying or have rehearsed the lie many times may not show such anxiety and thus pass the test.â€
Professor Don Grubin, professor of forensic psychiatry at Newcastle University, sees no reason why this would not work.
Stomach lie-detector test