Differentiation of truthful and deceptive criminal suspects in Behavior Analysis Interviews.

The Behavior Analysis Interview (BAI) is a commonly used procedure designed to assist investigators in distinguishing between suspects who are concealing their involvement in a criminal event (deceptive) from those who are not (truthful). During a BAI a protocol of questions is asked and suspects' verbal responses and accompanying nonverbal behaviors and attitudinal characteristics are assessed. Based on this assessment the likelihood of involvement in the criminal event is determined. The purpose of this study was to determine the effectiveness with which trained evaluators were able to distinguish between truthful and deceptive suspects undergoing BAIs. Sixty videotaped interviews, 30 of truthful and 30 of deceptive suspects, were observed by four evaluators, each of whom independently scored suspect's behaviors and attitudes and judged the suspect's truthfulness. The results showed that, excluding inconclusive decisions, evaluators' average accuracy on truthful suspects was 91% and on deceptive suspects, 80%. Suspects' status did not affect confidence of evaluators' decisions but confidence was greater when correct as opposed to incorrect calls were made. Deceptive suspects manifested "theoretically" predicted behaviors and attitudes of "deceptiveness" to a significantly greater degree than did truthful suspects. The BAI appears to be useful for investigative purposes in order to differentiate between suspects who are concealing involvement in a criminal offense from those who are not.