• The effect of co-offender planning on verbal deception

      Chan, Stephanie; Bull, Ray; Home Team Behavioural Science Centre; University of Derby (Taylor & Francis, 2013-09-13)
      Previous deception studies have mainly examined individual mock perpetrators and their deceptive behaviours during interviews, but not all crimes are committed by single perpetrators. In the present study, 48 mock perpetrators were individually interviewed after carrying out a mock theft in pairs. The time available for co-planning prior to the interview was manipulated so as to examine its effects on participants’: (1) verbal cues to deception; (2) cognitive load; and (3) attempted speech control during the interview. Having time available for planning was associated with greater statement immediacy, plausibility and within-pair consistency, but not with cognitive load or attempted control.
    • Helping to sort the liars from the truth-tellers: The gradual revelation of information during investigative interviews

      Dando, Coral J.; Bull, Ray; Ormerod, Thomas C.; Sandham, Alexandra L.; University of Wolverhampton; University of Derby; Lancaster University; Department of Psychology; University of Wolverhampton; UK; School of Law and Criminology; Derby University; UK; Department of Psychology; Lancaster University; UK; et al. (Wiley, 2013-04-20)
      Research examining detection of verbal deception reveals that lay observers generally perform at chance. Yet, in the criminal justice system, laypersons that have not undergone specialist investigative training are frequently called upon to make veracity judgements (e.g., solicitors; magistrates; juries). We sought to improve performance by manipulating the timing of information revelation during investigative interviews. A total of 151 participants played an interactive computer game as either a truth-teller or a deceiver, and were interviewed afterwards. Game information known to the interviewer was revealed either early, at the end of the interview, or gradually throughout. Subsequently, 30 laypersons individually viewed a random selection of interviews (five deceivers and five truth-tellers from each condition), and made veracity and confidence judgements. Veracity judgements were most accurate in the gradual condition, p < .001, η2 = .97 (above chance), and observers were more confident in those judgements, p < .001, η2 = .99. Deceptive interviewees reported the gradual interviews to be the most cognitively demanding, p < .001; η2 = .24. Our findings suggest that the detection of verbal deception by non-expert observers can be enhanced by employing interview techniques that maximize deceivers' cognitive load, while allowing truth-tellers the opportunity to respond to evidence incrementally.