Not only can words take on different meanings when considered in different contexts, but all behaviors must be considered within the context of the communication, the environment in which they occur and within the individual displaying the behavior. There are a number of specific considerations relating to context when assessing behavior symptoms of truth or deception:
One of the principles of behavior symptom analysis is that there are no behaviors unique to truth or deception. Depending on the content of a response to the investigator's question, identical behaviors can be interpreted as either indicative of truth or deception. Consider the following two examples:
Q: "Who do you suspect may have stolen this $1,000?"
A: "I don't have any proof but we have an employee Patrick who we almost didn't hire because of credit problems, and I really don't know him very well because he's new and I wonder could he do something like this. Then there's this girl Kathy who has a boyfriend in jail for murder. She calls in sick a lot and I've always been leery of her." [During this response the suspect picked lint from her skirt, covered her mouth with her hand, exhibited poor eye contact and decreased her volume when discussing Patrick.]
Q: "What is your understanding for the purpose of the interview with me this afternoon?"
A: "I guess some woman is saying that I did something to her over the weekend. I really don't know what's going on. All of a sudden they picked me up and I was in a police car and I really didn't do anything so I'm not really sure." [During this response the suspect picked lint from his pants, covered his mouth with his hand, exhibited poor eye contact and decreased his volume at the conclusion of his response.]
While both of these suspects exhibited identical nonverbal and paralinquistic behaviors during their response, considering the content of their respective responses, the first suspect's behavior supports innocence whereas the second suspect's behavior supports guilt. The first suspect experienced anxiety, uncertainty and shame when revealing her suspicions toward two coworkers. It is appropriate for her to be worried about being incorrect in her assessment, experience concern that something may happen to these coworkers as a result of her statements and perhaps even fear of retaliation from the coworkers for naming them. When evaluating her nonverbal and paralinguistic behaviors within the context of her response, they are clearly appropriate.
The second suspect, however, is experiencing anxiety, uncertainty and guilt when responding to a question that addressed his understanding for the purpose of the interview. These thoughts and emotions are not consistent with the content of his response. The probable explanation is that the interview represents a threat to the suspect because he committed the crime under investigation.
When I visit my son who lives outside of Los Angeles, I often have to drive on the 12-lane freeway. When doing so, my eyes are locked straight ahead, my hands are fixed at the 3 and 9 o'clock position on the steering wheel and I appear distressed and anxious. For someone accustomed to driving county roads in rural Wisconsin, my behavior is entirely appropriate.
However, consider an individual approaching a border patrol check point. His eyes are locked straight ahead, his hands fixed and the 3 and 9 o'clock position on the steering wheel and he appears distressed and anxious. Within this environment, the suspect's behavior is typical of someone smuggling contraband and he should be pulled aside for further questioning.
In another example, consider that a police officer is questioning a suspect on a street corner about possible involvement in a recent purse snatching. The suspect exhibits poor eye contact, puts his hands in his pockets and offers guarded responses to the officer's questions. These behaviors indicate the suspect lacks confidence and is experiencing possible fear. However, are the behaviors the result of fear of being caught lying or the fear that friends and neighbors will believe the suspect has engaged in criminal activity? We really don't know.
On the other hand, if these same behaviors were observed while questioning the suspect alone in an interview room, the investigator can eliminate outside environmental factors as possibly causing the behavior symptoms. Within a controlled environment, the investigator can have greater confidence attributing behavior symptoms to possible guilt and deception.
This is not to say that symptoms of guilt, fear or decreased confidence cannot be meaningfully interpreted in an uncontrolled environment. Many crimes have been solved by responding to behavior symptoms observed during a relatively benign traffic stop or simply by questioning someone who appears to be inappropriately anxious or nervous. However, the investigator's confidence of forming opinions of guilt or innocence should be tempered in an uncontrolled environment.
Individual Differences within Suspects
When I walk into an interview room to meet a suspect and see a bible (or other religious artifact) conspicuously displayed on the desk next to the suspect, I know there is a high probability that this person is guilty. However, on occasion, I have interviewed very religious suspects who have brought religious articles with them to the interview and who turned out to be innocent.
Many people have personal idiosyncrasies within their behaviors. Some of these are learned. For example, a suspect with a military background would typically refer to an investigator as "sir". That is their training and it is not suspicious. On the other hand, it is not typical for a gang member to refer to the investigator as "sir". Under this circumstance the use of the word "sir" is not appropriate and probably represents an effort to manipulate the investigator.
Other intrinsic suspect differences are the result of culture such as eye contact, proxemics and respect for authority or elders. Medical diseases and the side-effects of some medications can also affect a person's behaviors such as gait, facial expressions, tremor, and other symptoms of anxiety such as a dry mouth. Finally, there are personality differences which affect self-confidence, anxiety tolerance or comfort levels when dealing with people in authority.
Individual suspect differences can often be identified by establishing baseline behaviors at the outset of an interview. This is done by asking non-threatening background questions. After a couple of minutes of casual conversation, including questions about medications and general health, an investigator is able to identify individual differences within a suspect.
In conclusion, many laboratory studies investigating the validity of behavior symptom analysis are flawed because they attempt to identify specific behaviors that reveal truth or deception; indeed, there are no behaviors unique to truth or deception. During an interview a suspect's behavior and exhibited attitudes must be evaluated in context. Specifically, the behavior must be considered within the content of the suspect's verbal response, the environment and other circumstances of the questioning. Consideration must also be given to possible individual differences within the suspect's behavior and the general population.