How Useful Would Psychological Research Into The Detection Of Deception Be In Assisting You With Your Investigations? Are There Limitations To The Research Which Would Put You Off Relying On It?

Buller and Burgoon (1996) defined deception as, "a sender's knowingly transmitting messages intended to foster a false belief or conclusion in the reliever". Deception has been studied as far back as Freud (1905), "He that has eyes to see and ears to hear may convince himself that no mortal can keep a secret. If his lips are silent he chatters with his fingertips, betrayal oozes out of him of every pore". Freud is speaking of the non-verbal cues which can disclose what our mouths try to hide. It is these non-verbal cues which are focused

on heavily in the detection of deception when interrogating suspects. This essay will discuss the methods of detection used within police interrogation of suspects and aim to find the positives and negatives of these techniques with particular reference to psychological research carried out within the field.

In the past century the issue of deception has been greatly debated and researched within the world of psychology. Opinions on non-verbal cues of deception have fluctuated greatly, however, with every new piece of research conducted, the understanding of the indicators has deepened. Polygraph tests, although widely used in the U.S. are considered to be unreliable and this has increased the need for research into verbal and nonverbal cues, such as facial expressions (Adelson, 2004). Buller et al (1991) found that interrogators rely heavily on nonverbal behaviour when they are attempting to detect deception, hence the need for more knowledge on the true cues.

Zuckerman et al. (1981) found that the most common deception cues were decreased gaze, decreased smiling and slower speech rate. If people shifted position, hesitated whilst they spoke and paused before responding to questions they were also judged to be lying.

Three hypotheses of deception were proposed which aimed to account for deceptive behaviour. P. Ekman (1988, 1992) proposed the emotional hypothesis and the cognitive hypothesis. He suggested that, in accordance with the emotional hypothesis, liars would be emotionally aroused whilst deceiving. He proposes that deception is accompanied by any one of emotions such as guilt, fear of being caught or experiencing "duping delight" (that is, the deceiver is excited at the prospect of deceiving the person they are lying to). The emotional hypothesis would explain the display of "nervous behaviours" such as speech hesitation and a decrease in gaze. Both of which would be signs noted in the detection of deception in a police case.

In his proposal of the cognitive hypothesis Ekman suggests that when a person deceives they experience a high cognitive load; a person who deceives experiences the mental strain of formulating and sustaining a convincing lie. Goldman-Eisler (1968) found that behaviours associated with high cognitive load are evident in those who deceive, for example, speech hesitations and pauses before answering questions.

G. Kцhnken proposed the last of the three hypotheses, the attempted control hypothesis. This suggests that liars are aware of the indicators of deception and so make a concerted effort to control behaviour. This approach would explain the demonstration of decreased movement. To a police officer investigating a case this would include, for example, less fidgeting, as opposed to the predicted increase in fidgeting.

B. DePaulo and W. Morris proposed that their were three factors which should be anticipated when detecting deception. The first, they suggested, was an association between deception and dilation of the pupil, often associated with tension and concentration. This would be difficult to assess in the situation of police interrogation as it is a minute change, un-noticeable from a distance. The second is that, when a person is lying their voice seems to become higher in pitch. This would be useful in police investigations with face to face interrogation as this would be something detectable to a well trained ear. The third is that liars do not appear to fidget more. This would be useful knowledge for police investigators to have as the general assumption appears to be that a liar would fiddle more than someone who was telling the truth.

Ekman et al (1978) published the Facial Action Coding System (FACS), a manual which describes how to put facial expressions into categories according to the muscles that are used to produce them. Ekman claimed the FACS to improve detection accuracy rates, raising them to up to 90 percent.

Anver Less (1983) noted, whilst interrogating Adolf Eichmann, a Nazi officer, that Eichmann consistently displayed the same specific cues whenever he told a lie. With regards police interrogation this would be useful in cases where information is built up over a period of time so that the officers become frequented with the specific cues used by the liars. As John M. Grohol (1999) suggests, "If you've known someone for years... your chances of detecting truthfulness is likely higher (since you have become accustomed to the signs of lying in the other person)".

Although the research into nonverbal cues of deception does seem to bring to light some useful information for police interrogations there are still problems with relying on this as a method of seeking the truth. As DeTurck and Miller (1990) suggested, it is easier to deceive someone than it is to distinguish who is telling the truth due to the common usage of deception in our everyday lives.

DeTurck and Miller (1990) also noted that there were no universal standards widely accepted as the basic deception cues. This has implications for police interrogations as different officers may be looking for different cues causing unreliability in results.

Kцhnken (1987), did research into whether police officers could be trained to detect deceptive eyewitness statements. Officers were asked to decide whether or not the person was lying and to indicate how confident they were of this judgement. Those who indicated that they were very confident were more likely to be wrong than those who said they weren't 100% sure. This shows that, in the case of police officers, being confident doesn't necessarily mean getting the right result.

Vrij (2000) found that most people believed that if someone was lying they would exhibit an increase in body movement, however Sporer and Schwandt (2002) found that liars tend to have fewer leg/foot and hand/arm movements than those that are telling the truth. Sillars (1991) suggests that nonverbal cues are misread 70% of the time.

A problem also arises with the widespread use of a book by Inbau, Reid and Buckley (1986), Criminal

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