Judgements of Deception and Accuracy of Performance in Eyewitness Testimony
Desmarais, Sarah, Yarmey, Daniel, Canadian Journal of Police and Security Services
Undergraduate psychology students were shown a videotape of eight eyewitnesses, four of whom were instructed to respond truthfully, and four to respond deceptively, in their descriptions and photo identification of a target person. In addition to being truthful or deceptive, the eyewitnesses were accurate or inaccurate in their photo identifications of the target. The students rated each eyewitness on their accuracy of testimony, honesty, competence, confidence, and credibility, and also indicated which verbal and nonverbal cues guided their ratings. Students were not able to objectively detect deception and accuracy of identification significantly better than chance. However, subjective beliefs regarding characteristics suggestive of honesty and deception in eyewitnesses, and accuracy and inaccuracy of eyewitness identification, were significantly differentiated.
Although eyewitnesses may be trustworthy, credible, and accurate in their descriptions and identification of a perpetrator, they also can be deceptive because of an unwillingness to be involved, a distrust of the police and the justice system, and/or fear of possible retributions from the suspect or his/her friends. Deception has been defined as to "knowingly transmit(s) a message intended to foster a false belief or conclusion by the receiver" (Burgoon, 1994, p. 359). In interactions with suspects, eyewitnesses, and complainants, law enforcement professionals are charged with the difficult and critical task of identifying deception and accuracy. The objectives of this investigation were to explore different subjective indicators of deception and accuracy of identification, and to determine if university students could differentiate between accurate and inaccurate eyewitnesses, and truthful and deceptive eyewitnesses, based upon their observations and interpretations of verbal and nonverbal behaviour.
Researchers have shown substantial interest in the investigation of verbal and nonverbal correlates of deception (e.g., Ekman, O'Sullivan, Friesen, & Scherer, 1991; Hartwig, Granhag, Stromwall, & Andersson, 2004; Watkins & Turtle, 2003). However, with the exception of studies by Parliament and Yarmey (2002) and Yarmey (2003), there has been limited attention given to experimental investigations of deception in eyewitness identification. Most experimental studies on the detection of deception have involved laboratory investigations of the ability of participants to discriminate between truthful and deceptive statements and the interpretation of body language. With some exceptions, such as American Secret Service agents, Federal officers, and clinical psychologists (Ekman & O'Sullivan, 1991; Ekman, O'Sullivan, & Frank, 1999), most people are relatively poor in making such discriminations. Accuracy levels rarely exceed 60% when chance alone accounts for 50% accuracy (Ekman, 1996; Vrij, 2000). Although not always the case, analyses of verbal and nonverbal behaviour show that liars in contrast to truth tellers tend to make more self-references, have higher-pitched voices, take longer pauses in their speech, have more speech hesitations or filled pauses (e.g., ers, uhms, ahs), and use fewer words in total to communicate (Stiff & Miller, 1986; Vrij, Edward, & Bull, 2001; Zuckerman & Driver, 1985). Meta-analyses on nonverbal differences between truth tellers and liars have demonstrated relatively few objective cues to deception (De Paulo, Lindsay, Malone, Muhlenbruck, Charlton, & Cooper, 2003). For example, research suggests that liars make fewer foot/leg and hand/arm movements, and fewer postural shifts and self-manipulations such as rubbing ones hand on the leg than truth tellers (De Paulo et al., 2003; Vrij, 1994). If anything, liars are more likely to be still rather than show an increase in body movement (Mann, Vrij, & Bull, 2002; Vrij, Edwards, Roberts, & Bull, 2000). Furthermore, in contrast to the long held belief held by both police agencies and lay persons, the avoidance of eye contact or gaze-aversion is not a reliable indicator of deception. …