Hand gesture & police interrogation
The feasibility of hand gesture in police interrogation
Since body language plays 55% to 65% role of human communication, it influences part of human communication behavior. Body language includes carriage, facial expressions, eye contact and gestures. All go into helping emerge person’s presence and making a connection with others. People can made gestures by hands, arms, shoulder, torso, legs, feet, but hand gestures are probably the most common in general. (1)
Hand gesture was used as common and efficient communication skills in daily live. For example, people shake hands when they complete an agreement, teachers set upright thumb to encourage children, sellers use the open hand gesture repeatedly in order to persuade people, and nurse put fingers up in front of mouth for reducing noise in hospital. Moreover, this may happened more often than you realize. People may say “I really like your idea” and cross arms over their chest. In this case, what they are effectively saying is “I don’t like your idea” or “ I don’t agree with you.” Hand gesture as one kind of nonverbal signals is helping to make sense in this situation. Usually it’s hard for people to realize they are doing this, as the gesture happened spontaneously and automatically. It’s common to see that people use a lot hand gesture even when they are talking on the phone and the person cannot see them. (2)
As hand gesture has important function during communication, so police interrogation, where takes much count of communicating, adopts it a lot. Hand gesture is bidirectional in police interview. Not only the police can use hand gesture to improve the efficient of inquiry, but also suspects may use hand gesture unconsciously to express the truth. Polices may shake hands, give a thumb-up, or use guide gesture to ease witnesses’ tension. Additionally, unnatural gesture showed by criminals may help the police to find some hidden facts.
Two new theories, however, suggest that the use of hand gesture both by suspects or police officers is not that valuable. (3) However, it is a blow to police interrogation system, and even bigger blow to the value of non-verbal language in police interview. These new theories argues that hand gesture showed by suspects cannot be estimated as truth or not and police’s hand gesture can influence witness testimony. In other words, it cannot help police to estimate the value of witness testimony and will mislead the interviewees to confirm something that didn’t exist.
Previous Research and new improvement
The majority of the previous researches suggested that as liars move their arms and hands less than truth tellers and liars make fewer gestures to illustrate their speech, it’s reliable for police to observe non-verbal language, which helping to estimate the value of the evidence. However, Leif A. Strömwall pointed out some main problems in previous researches in “To act truthfully: Nonverbal behavior and strategies during a police interrogation”: short (less than a minute) video clips have been examined; the liars did not have the experience of transgressions; and the interviews did not have enough experience. In all, these factors point to a problem that most studies did not reflect the real-life police interrogation. Thus the conclusions about how liars and truth tellers differ in non-verbal language in a high-level situation cannot be drawn from previous studies.
The first shortcoming in previous researched was using short message from the senders. In the new study, Leif A. Strömwall chose to extend duration to 12-minute in order to add more pressure to the liars. Thus it is really hard for liars to defend themselves through the second half o f the interrogation.
The second critique of previous researches is that the participants did not fell much involvement of the research and therefore they were unlikely to use non-verbal language to use deception. In the new experiment, Leif A. Strömwall and his colleagues let the “suspectcs” more involved in the task by asking them to do the “crime” in real. Feeling more personal in the research will let them try their best to defend themselves in the interrogation.
The third change was that as previous research missed out on examining actual police officers as interrogators, Leif A. Strömwall invited experienced true police officers who have high level interrogative skills which can make the suspects showed more non-verbal language during the interrogation. (4)
New research on value of suspects’ hand gesture
In the “To act truthfully: Nonverbal behavior and strategies during a police interrogation” Leif A. Strömwall, Maria Hartwig, and Pär Anders Granhag who from Goteborg University made a research on difference of non-verbal language using by truth tellers and liars during police interrogation. They used 30 persons (21 females and 9 males) with age ranges from 18to 53 years. Moreover, all participants received a monetary compensation of 300 SEK (about $30) and if they can convince the police to believe them, they can get extra 200 SEK (about $20). On the other side, 30 police (11 females, 19 males) participated too. All of them had at least 5 years experiences as criminal investigators.
All the interviewees were divided into four groups: 2 lying groups and 2 truth-telling groups and all the participants were told to go to a nearby convenience store or a bakery. The truth tellers bought something and returned; the liars either bought or sold fake drugs. After giving them 2 hours for preparation, the police began their interrogation.
The result (see Figure 8) showed no difference between the truth tellers and liars in non-verbal behavior especially in the hand gestures, which was in contradiction to the widespread belief that liars and truth tellers are possible to distinguish in interrogation. There is possible answer to the surprise result. Under the high-level interrogation situation, both liars and truth tellers were try their best to not to make extra gestures in order to present credible impression. (5)
Experiment of hand gesture’s “misleading” theory
Some people may suggest if police use hand gesture during the interrogation can help the witness tell the truth. However, Dr. Daniel Gurney, who is a psychologist at the University of Hertfordshire, argued that hand gesture may have the same effects on human. If someone asks, for instance, “how big is your toy car?” people might respond differently than the same person asked, “how small is your toy car?” This is because that the wording of the first sentence will guide you to think your toy car is bigger than average. During the police interrogation, both the witnesses are easy to become sensitive and emotional. Thus both the spoken language and non-verbal language will become much easier to influence people’s respond.
Based on the above hypothesis, Dr. Daniel Gurney designed an experiment on the new theory which used hand gesture during the police interrogation will mislead witness to believe something that did not exist. During the experiment, 72 participants had been divided into three groups. Group one and group two had been showing two different types of misleading gesture and group three can only heard the interviewer’s voice.
All participants groups heard the interviewer ask the same questions such as “was the man wearing any jewelry?” In group one the interviewer used a gesture conveying misleading information with a “touching finger” – “ring” gesture. In group two the interviewer asked the question while showing a “grasping wrist” – “watch” gesture (see Figure 9). Moreover, participants were asked about the detail information they remember afterwards.
The statistic result revealed that in the first critical question test, the participants in group one which be showed “touching finger” – “ring” gesture responded that they saw ring which was three times more than the number of people answered watch. In addition, all the participants in group two said that they saw watch on the interviewer’s hand and even someone remember the color of the watch. Overall result showed that interviewees were more likely to claim seeing details that were conveyed to them through gesture. (6) (see Figure 10)
Therefore, during police interrogation, in general, police interviewers want to control the word they used and the question they asked, which shouldn’t be leading in any direction to their interviewees. However, unconscious hand gesture can still “give away” an answer direction, which may be the answer the police want to hear. This “misleading” experiment highlighted the importance of realizing the risk of using hand gesture during the police interrogation.
Although as one of the body language, people use a lot of hand gesture in daily communication, there are some hidden risk and disadvantage to use it in the serious police interrogation. The two new areas of researches highlight the importance of considering the danger that nonverbal information could mislead witnesses and the shortcoming of the hand gesture’s value from suspects. Same as the verbal language, body language is not a 100% truth language that people can believe on it. The next step of hand gesture may lead to discuss how to decrease the disadvantage of using hand gesture in police interrogation or maybe invent a new way to do the interrogation.
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1 “Hand Gestures,” Public Speaking Tips, accessed March 18, 2012, http://www.speaking-tips.com/Articles/Hand-Gestures.aspx.
2 “Research,” Danielgurney, accessed March 18,2012, http://www.danielgurney.net/.
3 Ibid. ; Maria Hartwig, Pär A. Granhag, Leif Stromwall, Ann G. Wolf, Aldert Vrij and Emma Roos af Hjelmsäter, “To act truthfully: Nonverbal behaviour and strategies during a police interrogation,” Psychology, Crime & Law 12:2 (2006): 207-219, accessed March 18,2012, http://dx.doi.org/10.1080/10683160512331331328.
4 Maria Hartwig, Pär A. Granhag, Leif Stromwall, Ann G. Wolf, Aldert Vrij and Emma Roos af Hjelmsäter, “To act truthfully: Nonverbal behaviour and strategies during a police interrogation,” Psychology, Crime & Law 12:2 (2006): 207-219, accessed March 18,2012, http://dx.doi.org/10.1080/10683160512331331328.
6 “Can misleading hand gestures influence eyewitness testimony? ” Danielgurney, accessed March 18,2012, http://uni-form.co.uk/dangurn/posters/canmisleadinggestures(gurneypine2011).pdf.