Liars make fewer body movements than truth tellers when being interviewed, according to psychological studies, and highly motivated liars make the fewest movements of all. In "Creating Suspects in Police Interviews," Lucy Akehurst and Aldert Vrij explore how this phenomenon intersects a different phenomenon-that the behavior of the interviewer can influence the behavior of the interviewee. Their hypothesis was that police interviewers who make more non-functional body movements will cause interviewees to respond in kind, with the net effect that officers will falsely perceive a greater likelihood that the interviewees are lying. This hypothesis raises the possibility that police can create suspicion by their own approach to interviewing suspects.

Using college students, actors, and police officers in three carefully designed studies, Akehurst and Vrij produce data that suggest accepting the hypothesis of self created police suspicion. Study 1 divided college students into two groups, one interviewed by a "lively" police officer and the other by a "non lively" officer. This study found a significant increase in nonfunctional movements among those interviewed by a "lively" police officer.

Study 2 then found a significant correlation between suspicion in the minds of other police officers who evaluated the videotapes and the increased non-functional movements by interviewees. Study 3 confirmed this finding by using actors for both the interviewer and interviewee to control more carefully for other variables that might explain the results. These results, the authors suggest, may tell us something important about the process of making any judgment of credibility when interviewing someone.

The authors acknowledge the inherent methodological problems in studies of students and actors that seek "real world" psychological truths. Their use of veteran police officers to evaluate the videotapes removed one potential source of artificiality, though once again the officers knew they were participating in a study rather than a real investigation. Moreover, as the authors acknowledge, it was impossible to control perfectly the behavior of the interviewer. Factors other than the movements of the interviewers could have caused the results. These limitations aside, this is an important paper for what it suggests about the power of the police to control the interrogation process. Researchers have wondered why some studies do not find suspects less likely to make incriminating statements after they are told of the Miranda v. Arizona "right to remain silent." In showing the power police have over the behavior of suspects, this paper suggests an intriguing explanation.

Akehurst, L. & Vrij, A. (1999). Creating suspects in police interviews. Journal of Applied Social Psychology, 29, 1, pp. 192-210.