Lie Bias

Police Officers and Lie Bias

If the truth bias is due to the frequency of exposure to truths, it may be expected that in a highly deceptive situation and occupation a lie bias may occur. Therefore, research has examined whether [Page 599]the frequent exposure to suspects encourages police officers to be more suspicious and thus exhibit a lie bias. There is evidence to show that police officers have a tendency toward more commonly judging statements to be deceptive than truthful. Moreover, when compared with members of the public, police officers more frequently judge statements as deceptive. It appears that increased training and experience among police officers enhances deception detection confidence but has no effect upon actual accuracy.

Thus, the research illustrates that police officers have similarly poor lie detection performance to laypersons. This may be because of the lack of accurate outcome feedback that police officers receive on their deception judgments. If suspects believed to be deceptive are prosecuted, the officer's belief that he or she is good at detecting deception judgment is supported. However, an acquittal can be seen as resulting from legal technicalities and poor juror decision making rather than indicative of poor deception detection ability.

As with members of the public, police officers rely on inaccurate cues to deception, such as decreased eye gaze and increased movements. Lie bias is increased when deception detectors focus solely upon the nonverbal components of suspect interview behavior. Police officers who watched videos of actual suspect interviews were more likely to show a lie bias than officers provided with the accompanying interview audio and those given a combination of visual and audio material. This strongly supports the concept that the cues commonly but mistakenly associated with deception—gaze aversion and fidgeting—are actually more likely to occur in truthful suspects.

Research has shown that participants who were offered a financial reward for good deception detection performance actually performed worse than participants who were not offered a financial incentive. Furthermore, the motivated participants made more false detections (that is, falsely stated that innocent people were deceptive) than the low-motivation individuals. The possible reason for this is that motivated individuals tried harder and so paid more attention to the erroneous nonverbal cues often falsely associated with deception, rather than focusing on the actual content of deceivers' speech. Although conducted with student participants, this research suggests that the high motivation of the police to identify guilty suspects and thus detect lies may actually impair their deception detection ability.

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