Galit Nahari Department of Criminology, Bar- Ilan University, Israel Aldert Vrij

1. Are You as Good as Me at Telling a Story? Individual Differences in Interpersonal Reality-Monitoring Galit Nahari Department of Criminology, Bar-Ilan University, Israel AldertVrij Department of Psychology , Portsmouth University, UK ***This research was partially funded by the Israel Science Foundation.

2. Background One way of discriminating between truth tellers and liars is by analysing their speech.

3. Background RM is a content-based tool for detecting lies, that was based on the “Reality Monitoring” theory (Johnson & Raye, 1981). According to the RM lie detection approach: Truths are obtained through perceptual processes, and thus are more likely to be richer in detail and contain more perceptual, contextual and affective information than lies.

4. Background RM deception research has shown that: • truthful statements are typically richer in perceptual and contextual details than false statements • RM tool distinguishes truthful from false statements at about 70% accuracy

5. The current study However Variancein richness appears also withintruthful statements and within false statements. People differ in the way they provide true statements, and in the way they provide false statements.

6. The current study One indication for this variance is reflected by large range in the number of words provided. For example, In Nahari, Vrij, & Fisher (2012): Number of words provided by truth-tellers ranged between 60 and 331. Number of words provided by liars ranged between 50 and 303.

7. The current study In the current study, we focused on these individual differences, and explored how they effect RM assessments.

8. RM scores are related to personal characteristics public self-consciousness and ability to act were negatively correlated with RM scores (Vrij, Edward, & Bull, 2001) High and low fantasy prone individuals gave different descriptions (in terms of content qualities) of incidents they had experienced (Merckelbach, 2004; Schelleman-Offermans & Merckelbach, 2010).

9. If the tendency to provide rich or poor accounts is indeed related to personal characteristics, then this tendency should be stable. Our first hypothesis was : the tendency to provide rich or poor statements is stable across situations (different types of statements).

10. In addition, • There are empirical evidences that people differ in the way they assess the quality of statements. • For example, while some participants perceive a statement as poor in detail, others perceive the same statement as being rich in detail (Granhag & Strömwall, 2000; Nahari, 2011).

11. Background Why does it happen? Individuals use different scales for judging richness in detail, and thus arrive at different conclusions. An individual's own experience with the subject matter being evaluated may determine his/her "decision threshold" (Glicksohn, 1993-94). Based on Glicksohn (1993-94) one may assume that an individuals’ scale for assessing richness may depend on their own experience.

12. Our second Hypothesis was: the tendency of an individual to provide poor or rich statements affects the way s/he judges others. In a way that, individuals who tend to provide rich accounts themselves may have higher expectations regarding the amount of details a statement should contain, and thus are more critic in their assessments.

13. Method Participants: 40 undergraduate students (Age M = 23.18) The participants were asked to leave the lab and go on their normal business for 30 minutes. They were told to make sure to carry out more than one activity and not to stay in one place for longer than ten minutes.

14. Method Upon returning to the lab after exactly 30 minutes, the participant was requested to write down in as much detail as possible: • A description of what s/he was doing during the last 30 minutes (’last-30-minutes statements’). • a description of an event s/he has personally experienced in his/her past (‘Past-event statement’)

15. Method The statements were coded with RM criteria. The coders counted the frequency of the perceptual and contextual details in these statements. For each statement we calculated: RM total scores and Number of words.

16. The number of words provided by the participant in both statements was highly and positively correlated, r = .65, p < .001. • the total RM scores of the two statements were highly and positively correlated, r = .74, p < .001 This supports Hypothesis 1: The tendency to provide rich or poor statements is stable across situations.

17. Does the tendency of an individual to provide poor or rich statements affects the way s/he judges others? To test this, each participant were asked to assess a target statement. Target statements: 40 statements were taken from Nahari et al.’s (2012) study. In that study participants wrote a statement about their activities during the last 30 minutes they spent outside the lab. An objective indication for the richness of the target statements: We coded the RM criteria of the target statements and calculated their RM total scores and the number of words.

18. Each participant had to assess only one target statement. • Each participant assessed a different target statement with different length and level of richness. Thus, for each participant we calculated the difference in richness between the statements s/he provided and the target statement s/he was assessed.

19. We calculated the difference between the averaged numbers of words provided by the participants in the statements and the number of words in the target statement they assessed (WD). WD = (words provided by the participant) – (words in target statement) This WD index gave us an idea of whether the participants provided more or less words in comparison to the target statement they assessed. WD < 0 the participant generated a shorter statement themselves than the target statement they assessed WD > o the participants provided a longer statement than the target statement they assessed

20. We calculated the difference between the averaged RM total scores provided by the participants in the statements and the RM total score in the target statement they assessed (RMD). RMD = (RM score provided by the participant) – (RM score in target statement) This RMD index gave us an idea of whether the participants provided richer or poorer statements (in RM terms) in comparison to the target statement they assessed. RMD < o the participant generated a poorer statement themselves than the target statement they assessed RMD > 0 the participants provided a richer statement than the target statement they assessed

21. The participants rated the features of a target Statement using 6-point scales.

22. *P < .05, **p < .01 ***p < .001 In addition, a negative correlation was found between the RMDs and total RM scores of the participants’ assessments in the target statements (r = -.44, p < .01)

23. That is, the longer and richer the participant’s own statements were, compared to the target statement, the less s/he perceived the target statement as detailed, vivid, interesting, realistic, credible, clear and richer in detail. This supports Hypothesis 2: The richer their own statements were, compared to the target statement, the more critical the participants were in assessing the target statement.

24. Some practical implications for the use of RM in the field: • If interviewees differ in the amount of details they include in their truthful statements, an investigator cannot know how many details to expect in a truthful statement. Consequently, an investigator cannot establish ‘norms’ or ‘cut-off points’ for veracity assessments based on the RM tool. A potential solution is to develop within-subject lie detection tools that allow comparison of the statement that is assessed to another statement provided by the interviewee and known to be truthful.

25. Some practical implications for the use of RM in the field: • The present experiment further showed that people evaluate others by using a subjective scale. That is, they judged the richness of other people’s statements in accordance with the richness of their own statements. It further complicates the use of the RM tool. To avoid this problem, investigators could stay away from global, subjective assessment procedures and instead could count the actual frequency of occurrence of RM details in a statement.

26. Thank you!