Opportunities to Detect Deception in a Forensic Setting

Lie detection during interviews - how to do it right

Posted Nov 03, 2010

I am often asked about the most effective strategies for discerning if someone is lying. It seems to be a topic of keen interest and of late, one stimulated by the show “Lie To Me.” Those of you who frequently read my blogs here on Psychology Today know that I feel it is important to share the science behind nonverbal communications, including what we know about detecting deception. But it is also important to be aware of the limits and boundaries of attempting to determine when someone is lying.

In What Every Body is Saying, I dedicated a chapter to detecting deception but with this caveat: “. . . most people—both laypersons and professionals—are not very good at detecting lies.” (Navarro 2008, 206) That line was written in 2007 and no research or experience thus far has dissuaded me from this belief. In fact, if you read my last post on “Nonverbals and DNA Exonerations”, you can see, very demonstrably, that we humans are terrible at detecting deception.  In those 261 DNA exoneration cases that I studied, the officers were wrong 100% of the time in assessing for truth and wrong 100% of the time in assessing for deception. Those numbers are not only astounding, they are shameful and a reminder of just how weak we are at detecting deception.

Having stated that, and obviously not making a lot of friends because some people let beliefs get in the way of facts, there are things that we can do, during a forensic interview process, to look for indicators of possible deception.

Often times in public settings, TV interviews, testimony before congress, I am asked to discern if the person being interviewed is being dishonest, is hiding something, or is just plain lying. To which I usually answer these are not good forensic settings and as such are not conducive to obtaining the truth nor assessing for deception. In fact, these public events are the worst possible kinds of interviews because they are not conducted by good interviewers. Many times the questions are drafted by congressional staffers or TV producers and the interviewers usually lack forensic interview skills. Also many of the questions are already known by the interviewee and worse, how they will be asked, which takes away from a more authentic forensic process.

Occasionally and quite by accident the truth is actually revealed in these public settings. A rare example of that was the case of the Balloon Boy Hoax in October 2009. In that case, the son of the notorious publicity seeker Richard Heene, inadvertently blurted out the truth during an on air interview with Wolf Blitzer. As the truth was revealed by his son, Richard Heene gave out a cathartic exhale (see video at 48-50 seconds), the kind we hear in forensic settings when a person realizes the jig is up and he has been found out. But these kinds of revelations hardly ever come out in public hearings or when individuals are confronted by the media because it is so easy to escape scrutiny when your interviewer is not prepared, does not know what to look for, nor is agile enough to follow-up with more pointed questions.

For the trained interviewer, there are ways to ask questions, in a forensic setting, where you have control of the environment and time is not a factor which can assist you in the process of assessing for deception. Notice I said “ask questions” because when people are allowed to make rambling statements, or they control the theater of the interview, they make it difficult to detect deception. However, when people are asked questions by a competent interviewer, in a proper sequence with focus, we actually have four opportunities to detect deception.

Four Opportunities to Assess for Deception

During any interview process, especially in a forensic setting, there are basically four opportunities, per question, to assess if the person is hiding something, troubled by a question, lying, or has some sort of guilty knowledge (only the guilty would know of very specific information).

 First Opportunity – Asking the Questions

The first opportunity is when you ask the question. As the interviewee hears the question look for behaviors that indicate the individual is freezing or restricting movement, is negatively affected by the question (compressed lips, chin withdrawal, ventral denial, etc.), or begins to pacify. These indicators are covered extensively in my books, What Every Body is Saying and Louder Than Words, as well as in many of my previous articles here on Psychology Today. A good interviewer asks the question and observes without being intrusive, without showing doubt or suspicion. Once each question is asked the interviewer waits and observes. What are they looking for? Any sign of discomfort which is usually seen on the body. This is one of the reasons I wrote "Clues to Deceit," so that the observer could look through over 200 behaviors associated with deception starting with the forehead all the way down to toes.

To the guilty, not all words have the same weight. A killer who used an ice pick will react to that word differently than if he is asked about a machete or a knife or a gun. Those words will not have the same limbic effect, because only the word “ice pick,” the instrument of death, is a threat to him (Navarro 2010, 25-29).

Second Opportunity – Processing the Question

The second opportunity to assess for deception or guilty knowledge is when the interviewee processes the question he or she just heard. Now it is true some people process questions very quickly while others take their time. No matter what, the interviewer is looking to see what are the effects on the interviewee as they process the question. Do they ask to repeat the question, a delay tactic perhaps? Are they troubled by the question?  Are they hesitant, do they look like they are doing trigonometry in their head (cognitive load), did they suddenly lock their ankles around the legs of the chair, are they looking straight ahead frozen, are their eyes moving around, did their blink rate go up? Changes in behavior or facial expressions mean changes in thinking or emotions. If the interviewee is struggling with the question or they look like they are troubled by the question, then it is for the interviewer to determine why.

Third Opportunity – Answering

The third opportunity to assess for obfuscation, deception or guilty knowledge is at the time the interviewee answers the question. As they answer, do they do so with conviction, without hesitation, with an unwavering voice, with dominance? Or do they restrict their arm movement, are they pacifying and soothing themselves, are they claiming less space, are they hiding their thumbs or their fingers, are the palms up rather than down, is the chin down rather than out, and are the shoulders rising toward the ears?  If they appear meek, lacking confidence, one shoulder is high while the other is low, the voice has a higher pitch, there is reluctance to answer, or their voice lacks emphasis, there may be issues there to further explore. All these things speak to the interviewer.

Fourth Opportunity Post Answer

The fourth opportunity to assess the interviewee is after he or she has answered the question. At that point a good interviewer will wait and watch creating a natural looking but pregnant pause so that the interviewee can be observed to see if there are any cathartic exhales, pacifying behaviors, wiggling in the chair, or heaving of the chest. Those behaviors also speak volumes to the interviewer. Most people don’t realize that after a question is answered, the interviewee will, if there is guilty knowledge, do some moving around, self adjusting, exhaling with puffed cheeks, prolonged exhale, self touching or self soothing to relieve the stress he or she has endured hearing the question, processing it, then answering that question. Here is one more opportunity to look for indicators of deception. Obviously, these techniques cannot be used by TV personalities or congressional inquisitors because the setting is just not conducive to this kind of lengthy and thorough forensic interview.

As I have stated previously here on Psychology Today and elsewhere, speech errors, hesitation, lack of confidence, indicators of stress, and pacifiers in relation to a question merely suggest that there are issues. They indicate some stimulus (a question) is creating stress and that there is something there to pursue. However, indicators of stress are not, and I caution, conclusively indicative of deception (Ekman 1991, 162; Vrij 2000, 5-31). As my friend Dr. Mark G. Frank, has repeatedly told me, “Joe, unfortunately, there is no ‘Pinocchio effect,’ when it comes to deception” (Navarro 2008, 230).


There may not be conclusive indicators of deception, but there are things that we can look for both in what is said, as well as in the body language of the individual. Experience teaches me that we have these four golden opportunities, for each question during a proper inquiry to look for those clues. In the hands of good investigators, these techniques often leads them to discern the truth, to bring to light things that are hidden, to detecting issues of concern, and sometimes, just sometimes, to detect a lie.                              


For additional information and a robust bibliography please contact the author at www.jnforensics.com. You can also follow Joe here at Psychology Today Blog Spycatcher or on Twitter at: @navarrotells.


Ekman P. (1991). Telling lies: clues to deceit in the marketplace, politics, and marriage.   New York: W.W. Norton & Co.

Navarro, Joe. 2010. Clues to Deceit. Kindle Edition, US

Navarro, Joe. 2010. Louder Than Words. New York: Harper Collins.

Navarro, Joe. 2008. What Every Body Is Saying. New York: Harper Collins.

Vrij, Aldert. 2000. Detecting Lies and deceit: the psychology of lying and the implications for professional practice. Chichester, England: John Wiley & Sons, Ltd.

 Copyright © 2010, Joe Navarro  Teaser image is of convicted spy Clyde Lee Conrad, a notorious liar.