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Forensic Psychology: A Comprehensive Synopsis (Vol. 2, Part 2)

© Michael Decaire

Upon arrest, or once suspects have been identified, the forensic psychologist as either a practitioner or a researcher still has a great deal to contribute towards the initial stages of the investigation. One such area is the contribution towards questioning and interrogation. A major contribution that is more recently coming to light is in regards to lie detection. While lie-detection equipment does exist within the realm of psychology, a very interesting area emerging in this filed is observational-behavioral lie detection.

One such method currently being used is Kinesic Interviewing. Kinesic Interviewing involves the examination of the inconsistencies between verbal and nonverbal behavior during questioning as a indicator of deception. In other words, does ones verbal behavior portray a different picture then ones non-verbal behavior. If so this is typically a sign of stress and thereby often of deception.

There is three areas of primary concern within behavioral lie-detection. The first is microexpressions. Microexpressions are brief facial expressions that occur in response to an event within ones environment. The expression occurs so quickly that we are unable to consciously prevent it from occurring. However, one's conscious response will quickly hide the reaction. It is this shift in facial expression that is evidence that an individual is trying to deceive.

A second area worth observing during behavioral lie detection is an individuals fixed characteristics. A fixed characteristic is one that is unchangeable by the individual and occurs in a specific consistent manner to stress. Two of the most consistent fixed characteristics are pitch and pupil dialation. In periods of stress the pitch of ones voice tends to significantly increase. When a question is asked suddenly and a pitch shift occurs one can assume that the person is experiencing stress due to the experience. Pupil dialation research has shown that there is a dramatic increase in pupilary size during periods of deception. While mechanical measures of these changes have been extremely consistent at detecting deception, it has been shown that trained individuals can also detect it at a significantly greater level then chance. Last month we examined inductive and deductive profiling. Outside of this role however a great deal can be offered to the investigative process by a forensic psychologist.

Non-fixed characteristics, the final characteristic of major concern to behavioral lie- detection, includes those non-verbal behaviors we can easily alter consciously. An example of these would include body movements, hand movements, and posture. Most individuals believe that a fidgety person is most likely to be deceiving. However, while this may be true for low stake lies as a sign of general nervousness, the opposite seems to be true for high stake lies. The reason for this is likely due to the "Illusion of Transparency." The illusion of transparency suggests that we have a tendency to believe our non-verbal behavior is more apparent to others then it really is, thereby when we attempt to prevent a display of behavior we tend to overcompensate making our nonverbal behavior inconsistent with what we are attempting to express.