Lying intensely mobilizes the brain, and this is seen in our micro behaviors. You still have to know where to look.
Imagine being able to detect a lie simply by observing the person you’re talking to. No need for a sophisticated polygraph or heavy-handed interrogation: the answer may lie right on his face. Because lying, far from being a simple act of speech, mobilizes our brain in a very particular way, and our body keeps track of it. Scientists have studied the movements that betray liars.
Researchers in behavioral psychology and neuroscience have become interested in a key phenomenon: cognitive load. Lying places an intense strain on the brain, which must simultaneously construct a fictional narrative, control it to avoid contradictions and mask signs of deception in its body language. This mental overload has measurable physical repercussions. To demonstrate this, the team analyzed the eye behavior of 32 participants during a simulated interrogation. The data was collected using electromyography (small electrodes near the eyes), a technique that measures the electrical activity of muscles and allows each eye blink to be precisely counted.
The results published in “The Journal for Life & Environment research” are clear: “Liars showed a decrease in blink frequency when lying, while those who told the truth showed an increase in blink frequency”. How to explain it? When the brain is highly stressed by a complex task, such as constructing a credible lie, it pauses certain reflex functions to concentrate its resources on the effort at hand. The blinking of the eyes, usually automatic, is thus slowed down. Another study published in the journal “Psychiatry, Psychology and Law” adds that liars establish more sustained eye contact than sincere people, in order to appear credible and to assess whether their interlocutor believes them.
To avoid missing any clues, you should also know that after a decrease in blinks at the time of a lie, we generally observe a rapid acceleration of the latter just after it, as explained the Vision Science Academy. Finally, thePupils are another telltale indicator. LPupil dilation is an involuntary response linked to cognitive load and emotional arousal. Liars have more dilated pupils than truthful people, with increases ranging from 4% to 8% of the initial diameter.
You now have all the knowledge to detect a lie. Be careful, however: the frequency of blinking and the size of the pupils naturally vary depending on many factors such as fatigue, dry eyes, taking certain medications or light conditions. To be truly meaningful, these clues must be compared to the usual behavior of the person concerned. If you suspect a lie, observe his behavior as a whole: a cluster of converging clues will always be more revealing than a single isolated sign.
