It may not sprout extra "Pinocchio" inches, but scientists have confirmed that the human nose undergoes a real physiological change when a person tells a lie.
Researchers at the University of Granada, Spain, used thermography to examine how the temperature of the human body changes when performing different activities, reports the Toronto Star.
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For those in need of a refresher, thermography is a scientific technique that uses special cameras to photograph the heat given off by an object. A thermographic print of an aroused human, for example, will reveal red or white hot patches around the genitals and chest.
So what part of the body heats up when we're lying? As it turns out, the tale of Pinocchio wasn't that far off. According to the Granada study, the nose gets a touch warmer when a lie is being told, as do the orbital muscles in the inner corners of the eyes.
Why do our noses get hotter when we're fibbing?
"Probably an increase in blood flow, but also insula activation," explained study co-author Emilio Gomez to Yahoo! Shine Canada. The insula is a part of the brain reward system, and only reacts to real emotions. "But it's also involved in the detection and regulation of body temperature," says Gomez. "It is a kind of marker of body state that informs the subject about his or her own feelings."
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So while you may think you're getting away with a lie, the insula knows, and may be providing subtle external hints by changing the temperature of parts of your face.
While this is interesting, chances are good you're not going to be able to reach out and touch the nose of a potential liar to test their trustworthiness.
Fortunately, another study released earlier this year by researchers at the University of British Columbia has identified some characteristics of lying that may be a bit easier to spot.
Their study, titled "Darwin the Detective: Observable Facial Muscle Contractions Reveal Emotional High-Stakes Lies" looked for signs of emotion in a person's facial muscles. The scientists examined videos of people making public televised pleas for the return of a missing loved one. Some of the "pleaders" were later proven to responsible in some way for the person's disappearance and making a dishonest plea.
The team found that the liars inadvertently raised their forehead muscles and the corners of their mouths, even when supposedly distressed. Those who were making an honest plea activated the muscles between their eyebrows, causing more genuine frowns and expressions of distress.
Lead author Leanne ten Brinke told The Telegraph that while the findings are important for forensic "lie catchers", they do not provide a fail safe "Pinocchio's nose."