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Liar Liar

Why did the chicken cross the road? Could be to get to the other side, could be that’s where he lived, or maybe he never crossed the road at all. I get all kinds of answers to questions in my business. As a spy, you never know when someone is giving you the truth or spinning a shell full of lies.

Or do you?

There are a lot of commonly held beliefs about what to look for to tell if someone is not telling the truth. Breaking eye contact, looking up or down, touching their face, covering their mouth, speaking with lots of ers and ums, repeating the question to buy themselves time to come up with a story, all of these can be seen as signs of deception. Yet even with all these clues, studies of those who are trained to detect lies find that their accuracy averages around 53% - not much better than flipping a coin.

Inventors have tried to create machines to detect lies. The Polygraph machine works by measuring breathing rate, heart rate (pulse), blood pressure and perspiration. (The name “Polygraph” comes from "Poly", meaning that multiple factors are being measured and "graph", a sheet of paper where the different measurements can be recorded to analyze). The theory is that when someone is under stress from lying, one or more of these factors will change and the machine will pick it up. The challenge is that some liars are not under stress at all when lying so there is nothing for the machine to pick up. This is why polygraph test results are generally not admissible in court.

Some enhanced Polygraph machines also measure arm and leg movements on the theory that a good liar can control their facial expressions but find it much harder to conceal deception in other parts of their body.

The face may be another way of telling if someone is lying. Dr. Paul Ekman first coined the term “micro expressions” for fleeting expressions on the face (sometimes lasting less than 1/25 of a second) that can give signs of deception. Dr. Ekman worked as a consultant on the TV series “Lie To Me” and he warns that even micro expressions are not a definitive sign that someone is lying. (Think you can spot a micro expression?)

Another physical clue to lying can be stress in the liar’s voice, leading to tiny changes in the way the voice sounds.  Although many companies offer commercial “Lie Detector” products (even phone apps) there is doubt about their effectiveness.

Some scientists are looking beyond physical measures like sweatiness and heart racing into the electrical patterns generated by the brain itself. Dr. Lawrence Farwell claims that his “Brain Fingerprinting” technology can detect deception not by finding lies but by clearly identifying when a subject is hearing something that is true. Does it work? There are still a lot of questions to be answered.

How good a lie detector are you? Ask a friend or family member to try an experiment with you. Have them tell you 3 things, at least one of which must be a lie. See if you can spot when your subject is not being truthful.


For more spy-themed science, be sure to check out our feature exhibition, Top Secret: License to Spy, which is open until September 5, 2016.