An investigation into deceptive alibi witness testimony.

'Weak' alibi evidence is the second leading cause of false convictions although psychological research on this issue is scarce. Understanding the factors contributing to the provision of false alibi witness testimony will highlight whether judicial instructions about alibi witness evidence are required to ensure fair investigations and trials. Utilising experimental and quasi-experimental research this thesis represents the first systematic investigation into the influences upon alibi witness deception.Study 1 set out to explore the factors influencing perceptions of deceptive alibi witness evidence in order to highlight the variables requiring further analysis later in the thesis. The study found that perceptions of false alibi evidence acceptability were influenced by an interaction between the type of deceptive evidence provided by the alibi witness (lie, false confession, evasion, omission) and the alibi witness' perceptions of the defendant's guilt (guilty, innocent, unsure of guilt). A qualitative content analysis supported these quantitative findings and also suggested that perceptions of the criminal justice system, knowledge of legal sanctions and the relationship between defendant and alibi witness were important in alibi evaluations. These factors were investigated further in the subsequent studies.Although study 1 highlighted the importance of deception type in alibi witness deception, the alibi research to date has examined solely alibi witness lies meaning there is no existing measure of alibi witness deception types that could be utilised in the thesis. Thus study 2 details the development of the False Evidence Questionnaire (FEQ) which found that alibi witness deception to consists of two factors; Omissions and Commissions. This supported the significant effect of deception type found in study 1. To further explore the role of attitudes to the criminal justice system in alibi witness deception study 2 also developed a multifaceted questionnaire; the Attitudes towards the Police and Courts Questionnaire (APCQ), to improve on previous one-dimensional measures of attitudes to the criminal justice system. The APCQ had five factors; Police Institution, Court Functioning, Punishment, Treatment of the Accused, Personal Safety. The structures of the FEQ and APCQ were demonstrated to be reliable and have a strong theoretical underpinning.Study 3 revealed that the APCQ Police Institution factor and participant age significantly predicted both the Commissions factor of the FEQ. Moreover, the APCQ Police Institution factor, participant age and the APCQ Court Functioning factor also predicted FEQ Omissions. These findings suggest that by improving perceptions of the police, false alibi witness evidence may be discouraged. Study 4 explored whether the significant effect of age could be attributed to increased awareness of legal sanctions amongst older adults. However, the study found that FEQ Omissions and Commissions are not influenced by punishment awareness illustrating that educating the public about the sanctions for false alibi evidence is unlikely to deter this behaviour. Study 5 used a mock police interview to gain a more ecological valid measure of the relationship between alibi witness and defendant upon alibi witness honesty.This revealed a significant association between unmotivated alibi witnesses (individuals with no/limited prior relationship to the defendant) and honesty inmock police interviews. Surprisingly, motivated alibi witnesses (individuals with an existing relationship with the defendant) were not found to have a significant association with either honesty or deception in the interviews. These findings support the conceptualisation of alibi witness deception as an altruistic act influenced by estimations of reciprocation likelihood. The study also found alibi witness intended honesty and actual honesty in the police interview were correlated, therefore validating the use of prospective questionnaire methods as utilised in studies 3 and 4. The final study demonstrated that although alibi witness motivation had a significant effect on mock juror perceptions of alibi witness honesty, this bias did not affect perceptions of defendant reliability or case verdicts. Nonetheless, judicial directions may be necessary to counteract juror scepticism towards motivated alibi witnesses.The thesis represents a unique development in the understanding of deceptive alibi witness evidence, the findings of which direct implications for criminal justice practice as well as future alibi research.