Pinocchio may be just a children's fairy tale, but Spanish scientists at the University of Granada recently investigated the so-called ''Pinocchio effect'' and found that our noses don't grow when we tell a lie, but actually shrink a bit.
Dr. Emilio Gómez Milán and his team developed a lie detector test that used thermography to tell if people were lying, and found that whenever participants in their research were being untruthful, the temperature of the tips of their noses dropped up to 1.2℃, while the temperature of their forehead increased up to 1.5℃. Scientists also found that drop in temperature at nose level actually caused it to slightly shrink, although the difference is undetected by the human eye.
''One has to think in order to lie, which rises the temperature of the forehead, '' Dr. Gomez Milan explained the findings. ''At the same time we feel anxious, which lowers the temperature of the nose. ''
For this study, researchers asked a number of 60 students to perform various tasks while being scanned by thermal imaging technology. One of these tasks involved calling a 3 to 4 minutes call to their parents, partner or a friend and telling a significant lie. Participants had to devise the lie by themselves during the call, and the thermal cameras picked up this ''reverse Pinocchio effect'' caused by the fluctuation (起伏) in temperature in the nose and forehead.
Interestingly, the thermal lie doctor picked up the temperature difference in 80 percent of test subjects, which is a better rate of success than that of any modern lie doctor.
''With this method we have achieved to increase accuracy and reduce the occurrence of 'false positives', something that is frequently with other methods such as the polygraph (测谎仪),'' said Dr. Emilio Gómez Milán, who added that law enforcement interviewers could one day combine other lie detection technology with thermal imaging to achieve better results.
The thermal lie doctor has been the most reliable in the world 
10% more than the popular polygraph.
