Reply to Mac Giolla and Ly (2019): On the reporting of Bayes factors in deception research

Bayes factors provide a continuous measure of evidence for one hypothesis (e.g., the null, H0) relative to another (e.g., the alternative, H1). Warmelink et al. (2019, Legal Criminol Psychol, 24, 258) reported Bayes factors alongside p‐values to draw inferences about whether the order of expected versus unexpected questions influenced the amount of details interviewees provided during an interview. Mac Giolla & Ly (2019) provided several recommendations to improve the reporting of Bayesian analyses and used Warmelink et al. (2019) as a concrete example. These included (I) not to over‐rely on cut‐offs when interpreting Bayes factors; (II) to rely less on Bayes factors, and switch to ‘nominal support’; and (III) to report the posterior distribution. This paper elaborates on their recommendations and provides two further suggestions for improvement. First, we recommend deception researchers report Robustness Regions to demonstrate the sensitivity of their conclusions to the model of H1 used. Second, we demonstrate a method that deception researchers can use to estimate, a priori, the sample size likely to be required to provide conclusive evidence.     

Understanding Children's Use of Secrecy in the Context of Eyewitness Reports

To investigate socioemotional influences on children's eyewitness accuracy, we examined children's reports for activities they were motivated to conceal. Forty-eight 3–6-year-old children participated in a standardized play session with their mothers. Half of the children were told by an experimenter not to play with certain toys, but did so at the urging of their mothers, who told their children to keep the play activities secret. The remaining children were not restricted from playing with the toys, nor told by their mothers to keep the play activities secret. Later, all children were interviewed about the activities with free narrative and detailed questions. Half were given an interview that consisted of highly suggestive questions; half were given an interview consisting of specific, less suggestive questions. Results indicated that older children who were instructed to keep events secret withheld more information than did older children not told to keep events secret. Younger children's reports were not significantly affected by the secret manipulation. There were no significant effects associated with interview type. We discuss implications for understanding the development of children's knowledge and use of secrecy, and applications of the research to issues that arise when child witnesses give reports in legal contexts.     

ID‐Check: Online Concealed Information Test Reveals True Identity

The Internet has already changed people's lives considerably and is likely to drastically change forensic research. We developed a web‐based test to reveal concealed autobiographical information. Initial studies identified a number of conditions that affect diagnostic efficiency. By combining these moderators, this study investigated the full potential of the online ID‐check. Participants (n = 101) tried to hide their identity and claimed a false identity in a reaction time‐based Concealed Information Test. Half of the participants were presented with personal details (e.g., first name, last name, birthday), whereas the others only saw irrelevant details. Results showed that participants′ true identity could be detected with high accuracy (AUC = 0.98; overall accuracy: 86–94%). Online memory detection can reliably and validly detect whether someone is hiding their true identity. This suggests that online memory detection might become a valuable tool for forensic applications.     

The Verifiability Approach to detection of malingered physical symptoms

Inspired by recent research showing that liars are reluctant to include verifiable details in their accounts, we explored in two studies (N?=?125; N?=?105) whether participants who report fabricated symptoms (‘malingerers’) present fewer verifiable details than participants who report genuine ill-health symptoms. In Study 1, participants were instructed to describe a typical day on which they had experienced a genuine or malingered symptom. Truth tellers’ statements included significantly higher proportions of verifiable details concerning the reported symptoms than malingerers’ statements. Compared with truth tellers, malingerers generated longer statements with more unverifiable details. In Study 2, we informed participants that their statements may be assessed for verifiable or checkable details. Malingerers often mentioned ‘false’ witnesses to provide checkable information and differences between malingerers and truth tellers in statement length, and checkable and uncheckable details were no longer significant. The utility and implications of the Verifiability Approach to detection of malingering are discussed.     

The effect of the presence and seating position of an interpreter on eliciting information and cues to deceit

The present experiment examined how the seating position of an interpreter during investigative interviews affects information elicitation and cues to deceit. A total of 60 native English speakers were interviewed in English and 200 non-native English speakers were interviewed in English (a non-native language) or through an interpreter who either sat next to the interviewer, behind the interviewee or interpreted via the telephone. Interviewees either lied or told the truth about a mock security meeting they watched. Interviewees who spoke in their native language provided more detail than interviewees who spoke in their native language through an interpreter or in a non-native language (English) without an interpreter. The latter groups did not differ. Additionally, the amount of detail differentiated truth tellers from liars in all conditions and interviewees found the presence of an interpreter to be a largely positive experience. The interpreter’s seating position had no effect on the findings.