Almost without exception research studies that attempt to determine whether or not investigators can accurately evaluate a subject's credibility based on their verbal and nonverbal behaviors yield results that are no better than chance....in other words investigators achieved an accuracy equal to 50-50...... flipping a coin.

And yet when conducting actual investigative interviews investigators can be highly accurate in evaluating a subject's credibility. WHAT GIVES?

The overwhelming majority of research studies are significantly flawed in their design.

For example, in many of the studies using students as "subjects" they are assigned different roles - some are "guilty" of the crime, such as stealing money from a teacher's desk drawer, and others are "innocent." A number of the students are instructed to lie about their status when they are subsequently interviewed by one of the research staff about their possible involvement in the theft. In reaching their conclusions the evaluators were generally no better than chance at determining the subject's status - "innocent" or "guilty".

In a number of research studies there was no opportunity to ask the subject follow-up questions after they told the investigator their story. For example, in one study several inmates are on camera telling us about two different crimes that they committed - one which they actually did commit, and one which they are lying about - they did not commit. The viewer/investigator is supposed to then determine which is the crime that they committed. The evaluators were generally no better than chance at determining which was the crime the inmate actually committed. In an actual case investigation, after the subject told their story the investigator would ask a series of questions to develop additional details, during which the subject's deception would oftentimes become apparent.

Here are some additional problems with the overwhelming number of such studies:

• The subjects (students/prisoners) had low levels of motivation to be believed or to avoid detection… there were no significant consequences if their deception was identified.

• The interviews of the subjects were not conducted by investigators trained in investigative interviewing techniques...there were very few if any follow-up questions to probe for additional details.

• The studies did not employ the type of structured interview process that is commonly utilized by investigators in the field.

The Research Studies Did Not Follow the Established Protocol for the Evaluation of the Subject's Behaviors

• In most studies, there was no attempt to establish a behavioral baseline for each subject so as identify changes from their normal behavioral pattern as they answered investigative questions.

• The research was based on the faulty premise that there are specific behavior symptoms that are unique to truth or deception…in fact, there are no behaviors unique to truthfulness or deception.

• There was no consideration given to the various factors that can affect a person’s behavioral responses, such as age, maturity, cultural influences, mental capacity, emotional and psychological stability, and the subject's physical condition at the time of the interview (drugs, alcohol, medical issues, etc.).

• Furthermore, in most research studies, the interview is evaluated in a vacuum, whereas in the real world, the investigative interview of a subject takes place in the context of an investigation. For example, by the time the investigator interviews a suspect, they may already have developed information about the subject’s relationship with the victim, their whereabouts at the time of the crime, their financial situation, and/or other relevant background information.

In the Reid Technique, we teach that there are several rules that all investigators should follow in the evaluation of a subject's verbal and nonverbal behavior symptoms:

- Establish the subject's normal behavioral pattern/baseline and then look for changes from that norm or baseline.**

- Read all behavioral responses across all three channels of communication: verbal, paralinguistic, and nonverbal.

- Read behavioral clusters - the overall behavioral pattern - not single, isolated observations.

- Consider timing and consistency for all nonverbal responses.

- Always evaluate behavior symptoms in conjunction with the case evidence and facts.

- Always evaluate the potential impact of possible factors, such as the subject’s mental capacity, psychological stability, maturity, culture, and physical well-being at the time of the interiew on their behavior symptoms.

If these rules are followed, a subject’s verbal and nonverbal behaviors can help in the assessment of a subject's credibility.

Almost without exception, these assessment rules were not followed in any of the research studies conducted by social psychologists/researchers to evaluate the value of verbal and nonverbal behavior symptoms.

PLEASE NOTE:

The most important element in evaluating a suspect’s potential culpability in committing a crime or an act of wrongdoing is not their behavioral responses, but the content of their statement as compared to the case facts and evidence.

The essential element to evaluate during an investigative interview is whether or not the case facts and evidence support the subject’s story or contradict what the subject has stated.

For example, if the subject states that he was not at the victim’s home on the day of the murder, but video from the apartment building across the street shows him entering the subject’s home on the day of the murder, the fact that he lied about that outweighs any verbal, paralinguistic or nonverbal behavioral responses that he might make during the interview.

** The following example illustrates the importance of establishing a subject's normal verbal and nonverbal behaviors before conducting the interview.

During the interview the subject is not listening to the investigator, he is constantly fidgeting, tapping his hands on the table, squirming in the chair, has poor eye contact, is excessively talking and blurts out answers before the questions are even completed. We may conclude that this obvious nervousness and anxiety is due to the subject's involvement in the issue under investigation.

However, these can be behaviors exhibited by individuals diagnosed with Attention-Deficit/Hyperactivity Disorder (ADHD)....which is why it is so important to establish the subject's normal behavioral pattern early in the interview.

In conclusion, if the rules outlined above are followed by the investigator during the interview process, then the evaluation of a subject's verbal and nonverbal behaviors can be a very helpful source of information regarding the subject's credibility.