Emotions in Lie Detection

Most people have heard of the seven basic emotions, whose universality was proven by scientist Paul Ekman. Understanding these emotions, recognizing how they appear, and knowing their purpose gives you a significant advantage in communication. But what do you know about detecting lies using knowledge of emotions?

The topic of applying emotional knowledge in the context of lie detection can be divided into several components:

• Emotions of the liar
• Microexpressions
• Faking emotions

Let’s revisit Paul Ekman. His fame was also boosted by his collaboration with Wallace Friesen, with whom he created the Facial Action Coding System (FACS). This system describes and codes all facial muscle movements and descriptors, and it has gained international recognition. While working on FACS, Ekman delved so deeply into the subject that it led to the discovery of microexpressions.

Microexpressions are another major contribution Ekman made to science. He was the first to notice that some people display emotional expressions for a very brief moment, which is hard to spot with an untrained eye.

What Are Microexpressions?

A microexpression is a brief, involuntary facial expression that appears when a person tries to hide or suppress an emotion. In lie detection, this type of emotional display is extremely important. Microexpressions cannot be consciously controlled and appear regardless of a person’s intentions. They last approximately from 1/25 to 1/5 of a second and serve as a window into a person’s true emotions.

This supports Charles Darwin’s idea from his book “The Expression of the Emotions in Man and Animals” that it is very difficult to suppress involuntary muscle contractions, especially when it is hard to produce those contractions at will. In other words, if you can’t voluntarily make a certain facial expression, it’s also hard to suppress it when it happens involuntarily.

Microexpressions allow us to read a person’s true emotions. In lie detection, a microexpression can signal a “double message,” where someone says one thing verbally but displays the opposite emotion nonverbally.

For example, a husband says, “This soup is delicious!” but shows a microexpression of disgust—a classic double message, or what we might call a “leakage” through the face. Or a suspect says, “Too bad you have no leads. I really want to help you find the criminal,” while showing a microexpression of contempt or joy.

The ability to see and recognize microexpressions can be trained. There are special programs for this (such as SETT, Mimika 3.0, and others). You can also develop this skill by observing people’s faces in real life.

How to Distinguish Genuine from Fake Emotions

Based on Paul Ekman’s research, here are some criteria for distinguishing consciously produced (fake) facial expressions from involuntary, spontaneous ones:

1. Morphology. The presence of “reliable” signals increases the likelihood that a facial reaction is involuntary. Almost every emotion has its own reliable signals. For example, joy is indicated by “crow’s feet” at the outer corners of the eyes; sadness by raised inner eyebrows; surprise by a relaxed mouth and short duration. Knowing these features and training your eye will help you spot them.
2. Symmetry. Asymmetrical facial expressions can indicate conscious control. Disgust and contempt may appear asymmetrical even when genuine, but all other emotions (joy, sadness, anger, fear, surprise) are ideally symmetrical on both sides of the face.
3. Duration of Emotions. An emotional display that is too brief (not a microexpression, i.e., less than 1/2 second) is more likely to be voluntary than spontaneous. The same goes for overly long displays (more than 5 seconds). Of course, the emotion itself matters—surprise can’t last long, and anger can’t be very brief.
4. Speed of Onset and Fading. Voluntary expressions start faster and more abruptly than spontaneous ones. Spontaneous emotions fade more slowly than they appear.
5. “Ballistic Trajectory” of Expression. A facial expression that develops with uniform acceleration, without “jerks,” is a sign of spontaneity.

How Liars Hide Their True Emotions

Liars use several techniques to conceal their true emotions, including simulation, neutralization, and masking.

• Simulation is displaying an emotion the liar does not actually feel. For example, a flight attendant showing warmth and friendliness to every passenger is simulating, as she doesn’t genuinely feel that way toward each person. Or a coworker fakes happiness at the news of a colleague’s new baby, without actually feeling any positive emotion. A suspect might simulate interest in helping investigators solve a theft.
• Neutralization is the opposite of simulation. Liars use it to hide strong emotions by suppressing all channels of expression and controlling their entire body. This is a difficult form of emotional concealment, requiring high self-control, focus, and emotional regulation skills. Someone using neutralization may appear overly tense, artificially emotionless, or “wooden.”
• Masking is a combination of the two previous forms. The person feels a strong emotion (for example, fear), tries not to show it, and instead displays a different emotion (for example, anger). This results in a mix of emotions that can’t be maintained for long, as it requires significant effort. Your task is to observe the person over time and, if possible, use gentle provocations to disorient them and reveal their true emotion.

In my practice, there have been several striking cases where facial leakage, manifested as a microexpression, allowed me to confirm my conclusion about a person’s involvement.