| Summary: | Although deception is considered an integral part of daily life (Kashy & DePaulo, 1996) as well as criminal activity, little is known about how individual differences affect the propensity for people to lie in everyday and higher stake situations, and the behaviours they exhibit. Deceptive ability can be impacted by factors of individual differences, stakes, motivation, and complexity (Vrij, 2001). Further, the accurate detection of deceit requires an acknowledgement that such factors can influence veracity judgements. The research reported in this thesis is an examination of how individual differences influence (i) beliefs about deception; (ii) the ability to lie when motivation is increased; (iii) deceptive behaviour when cognitive load is increased; and (iv) how this influences the decision whether or not to lie. Further, the ability of professional lie detectors and lay persons to judge veracity was investigated and compared. In addition, judges' subjective beliefs about the liars' behaviour were compared with the actual behaviour of liars as highlighted in previous deceptive research (DePaulo, Lindsay, Malone, Muhlenbruck, Chariton, & Cooper, 2002; Vrij, 2000). Finally, the relationships between judges' accuracy and confidence, and perceived ability and interview experience were examined. In study one individual differences in the beliefs people have about their ability to lie in everyday life and high stake situations were investigated via self-reports. The findings highlighted that people who are manipulative, are good actors, and manage the impressions they make on others, believed lying to be a more positive experience and that they were good liars in comparison to those who are anxious or sociable. Individual differences in the choice people made to lie (in an interview setting) were investigated in study two with a focus on a higher stake situation. There were overall differences between liars and truthtellers, where liars exhibited fewer smiles, a longer latency time and had a higher speech pitch compared to truthtellers. There were also individual differences found in the exhibited behaviour of liars and truthtellers. Study three investigated individual differences in the behaviours people exhibited while lying (in an interview setting) and their related beliefs (self-reports) concerning the influence of factors such as emotion, complexity and attempted control. The findings highlighted that good actors, manipulative people and impression managers exhibited 'honest' behaviours while lying and reported little arousal while lying, believing themselves to be good liars, whereas anxious and sociable people exhibited 'nervous' behaviours such as stutters and reported experiencing stress and guilt while lying. In study four, the impact individual differences, motivation, veracity, and complexity on deceptive and truthful behaviour was examined (in an interview setting). Differences were found in peoples' exhibited behaviours for all factors which provide interesting implications for the detection of deception. Study five focused on the ability of professionals (police detectives and custom officers) and lay persons to detect deception. This study examined the effects of interview experience and perceived ability on veracity judgements, in addition to demeanour bias, the accuracy-confidence relationship, and actual / believed cues to deception. The findings (amongst others) highlighted discrepancies between how people behave when they lie and how people think liars behave, that confidence and experience does not lead to accuracy in detecting lies, and that the individual differences of both judges and liars influence veracity judgements. The implications of the research findings are discussed in terms of increasing the effectiveness of detecting deception in the future and understanding what makes some people good liars and others easily detectable.
|
|---|
