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There is no behavior unique to lying

May / June 2016 (click here for printable version)

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People oftentimes associate specific behaviors with deception, such as lack of eye contact. But there are many reasons a person may not have eye contact with the individual whom they are speaking to, that have nothing to do with deception; for example, cultural considerations. In this Investigator Tip we will address the underlying principles for the proper evaluation of a subject’s behavior during the investigative interview. *

Behavior symptom analysis involves the study of inferences made from observing another person’s behaviors. On a daily basis we make dozens, if not hundreds, of inferences based on behavioral observations, such as that man is angry, that girl likes me, my child is hungry, my son did something wrong, that driver is lost, those two people don’t like each other, Aunt Martha is not taking her medications. This is such a natural phenomenon that it is easy to forget that there is an underlying process leading to these inferences. For example, a six-week-old child is heard crying in the nursery. The child was last fed four hours ago and eats about every four hours. The nature of the crying in the past has been relieved by feeding the child; ergo, the child is hungry. To be completely accurate, when making these behavioral assessments our mind should be thinking, “That man is probably angry,” “I think that girl likes me,” “I believe that my child is hungry.”

This article addresses behavioral inferences relating to detection of deception, primarily in a clinical, controlled environment. Within the scope of detecting deception, there are two broad inferences that are made through behavioral observations. The first involves inferences of guilt or innocence, that is, “Did this person engage in a particular criminal act?” The second involves inferences of truth or deception, that is, “When this person says such and such, is he telling the truth?” For case-solving purposes, it is important for an investigator to appreciate the distinction between “guilt” and “lying.” Consider the following exchange during an interview:

Q: “Have you ever thought about setting fire to your house for the insurance money?”

A: “Well sure. I think everyone has thoughts like that.”

This suspect’s verbal response to the investigator’s question is truthful. Yet, the content of the response infers guilt with respect to setting fire to his house. Research in the field of behavior symptom analysis generally indicates higher accuracies in identifying guilt or innocence, than truth and deception.

Finally, it is important to understand that some behavioral inferences have a higher probability of being correct than others. Consider that a suspect can clearly be seen on a surveillance video leaving the hotel room in which a woman was found raped and murdered. Upon questioning, the suspect denies ever being in the room. The fact that the content of his verbal behavior is contradicted by the video evidence strongly suggests the suspect’s guilt regarding the commission of the crime. During this interview, the suspect’s posture was rigid and frozen and, when asked if he had ever met the victim, he dusted off imaginary lint from his trousers. Furthermore, the suspect was wringing his hands and sweating even though the temperature in the room was set at a comfortable level. Although these behaviors are suggestive of the subject’s deception and possible guilt, they are much less so than the documented lie, as evidenced by the videotape.

To appreciate the nature of these inferences, it must be realized that communication occurs at three distinctly different levels:

1. verbal channel—word choice and arrangement of words to send a message

2. paralinguistic channel—characteristics of speech falling outside the spoken word

3. nonverbal channel—posture, arm and leg movements, eye contact, and facial expressions

When evaluating a suspect’s behavior for detection of deception purposes, there are five essential principles that must be followed in order to increase the probability that subsequent inferences will be accurate. Failure to recognize any of these principles increases the probability of making erroneous inferences from a suspect’s behavior.

There are no unique behaviors associated with truthfulness or deception. The behavioral observations an investigator makes of a suspect do not specifically correlate to truth or deception. Rather, they reflect the subject’s internal emotional state, cognitive processes, and internal physiological arousal experienced during a response. The emotional states most often associated with deception are fear, anger, embarrassment, indignation, or hope (duping). The cognitive processes may reveal concern, helpfulness, and confidence versus offering an unrealistic explanation for the crime, being defensive, or being overly polite. There are also internal physiological responses that cause external behavioral responses such as a dry throat, skin blanching, pupillary dilation, or blushing. Observed in isolation, certainly none of these behaviors should cause an investigator to conclude that a subject is telling the truth or lying.

Evaluate the consistency between all three channels of communication. When a suspect sends behavioral messages that are consistent within all three channels of communication, the investigator can have greater confidence in his assessment of the credibility of the subject’s response. However, when inconsistencies exist between the channels, the investigator needs to evaluate possible causes for this inconsistency.

Evaluate paralinguistic and nonverbal behaviors in context with the subject’s verbal message. When assessing the probable meaning of a subject’s emotional state, the subject’s paralinguistic and nonverbal behaviors must always be considered in context with the verbal message. Consider the following two examples:

Question (Q 1): Mike, have you ever been questioned before concerning theft from an employer?

Response (R 1): Well, um, two years ago I worked at a hardware store and they had an inventory shortage so all of the employees were questioned and, in fact, I did take some things from there. [Subject crosses his legs, looks down at the floor, and dusts his shirt sleeve.]

Q 2: Joe, did you steal that missing $2,500?

R 2: No, I did not. [Subject crosses his legs, looks down at the floor, and dusts his shirt sleeve.]

These two subjects displayed identical paralinguistic and nonverbal behaviors during their responses. However, the interpretation of the behaviors is completely different. In the first example the subject is telling the truth, but he feels embarrassed and possibly even threatened in revealing his prior theft. In the second example the verbal content of the subject’s response does not explain the accompanying nonverbal behaviors, so the investigator should consider these behaviors as reflecting possible fear or conflict—emotional states that would not be considered appropriate from a truthful subject, given the content of the verbal response.

Evaluate the preponderance of behaviors occurring throughout the interview. One of the findings learned through research is the importance of rendering opinions based on evaluating the subject’s behavior throughout the course of an entire interview. When evaluators I research studies were only exposed to individual questions within the interview, their accuracy was considerably less than when evaluating the subject’s responses to all of the interview questions. Similarly, the confidence of assessing behavior over a five-minute interview will be considerably less than if the behavioral assessments were made over a 30- or 40-minute interview.

Establish the subject’s normal behavioral patterns. Certainly there are non-deceptive reasons for a suspect to exhibit poor eye contact, respond to questions quickly or slowly, to scratch themselves, yawn, clear their throat, or change their posture. Before any of these behaviors can be considered a criteria of deception, the investigator must first establish what the subject’s normal behavioral patterns are. Consequently, at the outset of each interview the investigator should spend several minutes discussing nonthreatening information (perhaps casual conversation or collecting biographical information) so as to establish a behavioral baseline for the particular subject. Then, as the interview progresses and the subject exhibits behavioral changes when the issue under investigation is discussed, these changes may take on added significance.

The evaluation of a subject’s behavior for indications of truth or deception is a complicated endeavor and should be considered only one factor in the assessment of the subject’s possible involvement in the issue under investigation.

* Some of the text above is from our book, Criminal Interrogation and Confessions, 5th edition, 2013



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