The Face Does Not Lie
Thermal Imaging of the Face Can Detect Deception

June 8, 2003

How can you tell if someone is lying? Some police departments use a "polygraph" test to find out if a person is telling the truth. The polygraph, commonly called a lie-detector test, usually measures sweating, breathing rate, heart rate and blood pressure. Using a polygraph requires expert training and the test results can be difficult to interpret. Researchers at Honeywell Laboratories and the Mayo Clinic in Minnesota think that they have a new way to spot a liar: by measuring changes in heat patterns on a person's face.

The researchers asked volunteers to commit a fake crime. The "criminal" volunteers had to stab a mannequin, rob it of $20, and then say that they were innocent. Control volunteers knew nothing about the crime. All of the volunteers were asked about the crime while the heat generated by their faces was measured with a thermal imaging device.

When the criminal volunteers lied, the area around their eyes got hot. The heat patterns on the faces of control "innocent" volunteers did not change when they were asked about the crime. The thermal imaging correctly identified 75% (6 of 8) of the criminal volunteers as criminals and 92% (11 of 12) of control volunteers as innocent.

The mechanism responsible for the increase in a liar's facial heat is not known. The autonomic nervous system and areas of the brain, such as the amygdala and hypothalamus, become active when a person is under stress and may cause a liar's face to "light up."

Additional research is necessary to determine if this new technology is accurate and reliable in other situations. Perhaps in the future, when people are asked questions during police investigations or job interviews, they will also be asked to have their faces measured for heat. It may be that words can lie, but faces cannot.


  • Pavlidis, I., Eberhardt, J.L., and Levine, J.A., Seeing through the face of deception, Nature, 415:35, 2002.
  • Autonomic Nervous System - from Neuroscience for Kids

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