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Body language: The Lips Don't Lie

Updated: Aug 25, 2023

When it comes to feelings and emotions, the lips can be invaluable; they can even help us to detect psychological discomfort, which while not indicative of deception, are still useful. Ever notice when people are stressed, their lips disappear or get smaller? You often see this at the airport as flights are being cancelled or while watching a movie that is very tense. We certainly see it on the faces of those testifying before Congress, in politicians making painful declarations, and even in peoples' reactions to what others have said.

Lips convey a lot of information that is often ignored or not even observed. Rich with nerves and highly vascular, the lips react in real time to the world around us. So when people receive bad news or witness a horrific event their lips begin to disappear, becoming very thin as vaso constriction takes place. Under extreme stress they disappear completely or are compressed together.

In relationships, couples will immediately notice when their partner has issues because they notice the tightening or compressing of the lips. Even kisses will seem different under stress as blood flow is restricted which affects their fullness, warmth, and pliability. Our lips react to the reality of the moment and communicate accurately our feelings and sentiments to others.

Because disappearing or compressed lips are universal behaviors, controlled by the limbic system, these are behaviors that can be relied upon and are authentic. We don’t realize how our lips look and feel, but others will notice.

Lip biting, like lip compression, is one of the ways that we pacify ourselves when we are stressed. It helps to relieve tension that may be minor and transitory. However, as I note in my book The Dictionary of Body Language, when something more significant is bothering us, our limbic system, in reaction to events, will compel the lips to narrow and disappear if the stress is significant enough.

We can use these behaviors to assess the level of comfort and discomfort noticeable on those we are observing. Students getting ready to take tests will demonstrate their stress level with these behaviors as will individuals who are suddenly confronted with disagreeable circumstances. As an FBI special agent, I used these behaviors (lip compression, disappearing lips) to determine what specific subjects stressed the interviewee suggesting there might be “guilty knowledge."

One of the things I noticed early on in my career was that once people settled down, their lips would compress or disappear when they heard a specific question they did not like or while they were answering that question. I also found that the level of lip compression or disappearing lips varied with the level of stress caused by the topic.

For example, when I would ask someone, “Do you own a gun?” They would say “yes,” and then I would notice the lips would disappear or be compressed slightly. Then I would ask, “Do you own a “Smith and Wesson revolver?” their lips would not react all that much. However, when I asked, “Do you own a “Glock pistol?” knowing that this was the weapon found at the crime scene and unknown to the public, I noticed that the lips became really narrow and compressed and that the corners of the mouth would also turn downward . This to me was extremely significant in verifying that this individual was severely stressed by the question and most likely by his guilty knowledge.

In a forensic setting you quickly realize that not all words we hear have the same weight.  If you killed someone with an ice pick, you will not react to the question, “Did you kill her with a machete?” as you would if you were asked, “Did you kill her with an ice pick?” In polygraphy, this is called the “hidden key.”  By asking specific questions you can elicit very precise information as to what bothers an individual or, in some cases, that they have specific guilty knowledge.

Once more, as I have explained in previous articles and in my book (What Every Body is Saying), these behaviors (lip compression and disappearing lips) in and of themselves are not indicative of deception; they are, however, indicative of distress and tension. I use them to guide me in the investigation so that I can determine what information to pursue that is causing such distress. I can also use them to assess for comfort and discomfort in others.

So next time you are in a meeting, with a colleague, with your loved ones, or conducting a serious interview, watch those lips. They say so much and not just with words.

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