Interviewing to detect omission lies

Interviewees sometimes deliberately omit reporting some information. Such omission lies differ from other lies because all the information interviewees present may be entirely truthful. Truth tellers and lie tellers carried out a mission. Truth tellers reported the entire mission truthfully. Lie tellers were also entirely truthful but left out one element of the mission. In truth tellers’ statements, only the parts that lie tellers were also asked to recall were analysed. Interviews were carried out via the Cognitive Credibility Assessment, Reality Interview, or standard interview protocol. Dependent variables were the details, complications and verifiable sources interviewees reported. A questionnaire measured three deception strategies: ‘Tell it all’, ‘keep it simple’ or ‘paying attention to demeanour’. Lie tellers reported fewer details, complications and verifiable sources than truth tellers and reporting these variables was negatively correlated with the ‘keep it simple’ and ‘demeanour’ strategies. The type of interview protocol did not affect the results.