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detecting deception

Categories of Stress Behavior

by Stan B. Walters, CSP
“The Lie Guy®”

Each of us experience stress creating events on a regularly basis and in a large number of different settings. Everything from the simple aggravating issues of daily life up to and including the stress that is associated with creating and maintaining deception.  The ability of the interviewer to be able to accurately diagnose deception rests on his or her knowledge of which stress behaviors are those that are associated with deception versus those behaviors that are merely the result of “ambient stress” of the current interview setting.  Those individuals who fail at accurately identifying deception in other people invariably misidentify a large number of general stress behaviors as being signs of deception while at the same time failing to recognize reliable behavioral cues of deception. Understanding the classification of human stress indicators into the three basic categories of general, incriminating and discriminatory cues can dramatically improve the investigative interviewer’s deception detection accuracy.

The “general”category of stress cues is the largest and most diverse of all the three categories.  These are behaviors that each of us experiences in varying degrees throughout our day.  These cues are present when things are absolutely crazy in the mornings as everyone in the household scrambles to get ready for the day’s activities, the project at work is going badly, the relationship with another person is deteriorating, the bills are late, or one of your children has come home early with a surprise case of the measles and you’ve never had them!  This is the type of stress we experience when we are at the bank applying for a loan or when we are at the restaurant and we’re worried that your credit card may be other limit and will be declined when we “pick up the tab.”  It is these types of behaviors that we may describe as being nothing more than the “background” noise of human behaviors that goes on all the time.  Some of these symptoms include a louder voice along with higher voice pitch, agitated facial expressions, increased hand and arm behaviors and even a few speech flaws.  They are by no means signs of deception yet are often seized upon by the eye of many untrained or ill-informed observers as reliable signs of deception.  If these are signs of deception we all must be lying all the time!

The “incriminating” category of stress cues tend to be more prolific than the “lie signs” but there is nowhere as many as those that populate the “general” stress category.  These behaviors are more likely to be seen during moments of evasive response by a subject but will not specifically pinpoint to moment of deception by the speaker.  The presence of these symptoms appears to be more scattered and not always recurring when the issue is raised at a later time by the interviewer. At the same time both truthful and deceptive subjects are capable of generating these cues but we find that deceptive subjects generate are far higher number of them overall during their general response to some form of inquiry.  These can include stuttering, stammering, mumbling speech and general pausing.  These symptoms much like the “general” category are problematic in that they are often inappropriately given far more weight toward an end analysis of specific deception.  A more accurate analysis from observing these behaviors would be that the subject’s overall behavior “concerns” the interviewer therefore he or she should spend more time with the subject and ask in-depth questions regarding the specifics of the issue under investigation and watch to see if the subject begins to generate the stress signals that are capable of isolating the stress behaviors associated with deception.

The “discriminatory” category of stress cues are those behaviors that when observed under stringent scientific conditions have been found to be highly reliable in marking moments of deception.  It is this category that we focus on a great deal in Practical Kinesic Interview & Interrogation courses.  With a good understanding of the “general” and “incriminating” stress categories, the stress behaviors associate with deception become more obvious.  The interviewer will find this category populated with nonverbal behaviors such as aversion, negation, contradictions, and to some extent performance and control cues.  Verbal cues include the content category of “denial” as well as elements seem in the presentation of an “unclear thought line” or cognitive dissonance.

In-depth knowledge of the “incriminating” and “discriminatory” categories along with accurate recognition of their occurrences can dramatically improve the observer’s ability to spot deception.  Just as critical however is to understand the significance of the general stress behaviors. These cues can tell the interviewer a lot about the subject’s current emotional and cognitive state as well as the strength of the emotion being expressed.  These cues can guide the interviewer through the entire interview and allow him or her to maintain control over the flow of information and improve the quality of communication.  At the same time, the interviewer must still understand that “general” stress cues will often “populate” a deception cluster and can indicate level of severity of stress the subject is experiencing while perpetrating the lie.

The Subject Specific Interview Approach

by Stan B. Walters, CSP
“The Lie Guy®”


In recent years several behavioral science experts have focused their research efforts on reviewing hundreds of investigative interviews and interrogations.  There have been two goals of some of these studies.  One has been to determine how successful the interviewers are at accurately identifying and analyzing the behavioral signs of deception. The second has been to gain greater insight into the investigative interviewing process and learn why some interviewers and their methods are more successful than others.  The results of these studies have been both surprising and enlightening in several ways.

First, investigative interviewers generally do a poor job of spotting deception more than 50% of the time and frequently use behaviors to identify deception that have consistently been proven to be highly unreliable signs of deception. This will be the topic of a future “The Interview Room” article. Second, the interviewing tactics often taught and practiced by most interviewers generate the lowest number of incidents of admissions and confessions.  Despite what most of us as interviewers claim, we are in fact only successful at getting admissions and confessions about one-third of the time.

Two critical studies of the investigative interviewing process utilized the videotapes of nearly 1,000 interviews and interrogations.  The findings from these two studies will be surprising to many experienced and seasoned interviewers but when considered thoughtfully the results make perfect sense.  The two studies identified a multitude of interview and interrogations methods, techniques and strategies from numerous training sources and experts.  Each method was documented when it was used in any of the taped interviews and then correlated with how frequently an admission or confession occurred.  Many of the “tried and true” tactics that we as investigative interviewers swear by produce consistently poor results.  The one outstanding characteristic of the consistently successfully interview was the one that was “subject specific.”  By “subject specific” I mean that the interview dialogue and presentation of proof of evidence to the subject was based on the unique social, psychological, and personal history of the subject who was being interviewed.  It was consistently demonstrated that techniques that may have proven successful on some subjects was totally ineffective with others.  When the interviewer based his interview approach solely on a strict formula there would be a greater chance of failure. When the interviewer recognized the unique individual characteristics of each subject he was highly likely to be successful. Both studies demonstrated that this approach was associated with and admission or confession more than 90% of the time.

The key element in Practical Kinesic Interview & Interrogation® – Tactical Interrogation Phase is to recognize that personality, personal history of past experiences and the individuals unique thinking process is what makes each of us different from each other.  When the interviewer recognizes the unique combination of these factors for each subject and approaches the interview accordingly he or she will dramatically improve their admission and confession rate. The investigative interviewer must learn to perceive the incident from the subject’s point of view.  What would motivate him or her to commit the act – not what would motivate you or the last subject you interviewed act in such a manner.  After allowing the subject to narrate his version of the events, point out to inconsistencies in the story and contradictions between the story and the evidence.  Learn to identify what the subject believes they could lose by continuing their deception and what in the long run that they can gain by accepting responsibility for their actions in such a manner that they feel they will have some control in the outcome.

A frequent point we try to make in Practical Kinesic Interview & Interrogation® is first, to remember to interview the subject who committed the crime and not the crime that was committed. Second, stop interviewing the subject from a preset “game plan” – adjust your dialogue to the subject’s responses and behavior you see and hear during the interview. Finally, stop talking to the subject as if you are talking to yourself – he ain’t you!