Assessing the truth effect’s reliability and test–retest stability
Frank Calio, Lena Nadarevic, Jochen Musch · Consciousness and Cognition · 2025
The finding that repeating a statement typically increases its perceived validity is referred to as the truth effect. Research on individual differences in the magnitude of the effect and its correlates is scarce and has yielded rather mixed results. However, any search for replicable relations between the truth effect and other cognitive or personality variables is bound to fail if the truth effect cannot be measured reliably at the individual level and if the effect is not a stable phenomenon. We conducted two experiments investigating the split-half reliability and test-retest stability of the truth effect. To operationalize the magnitude of the effect, Experiment 1 used the between-items criterion and Experiment 2 used the within-items criterion of the truth effect (Dechêne et al., 2010). In both experiments, the truth effect's test-retest stability was found to be very low, probably due to a highly insufficient reliability of the measures that were used. While there may be meaningful and stable individual differences in the truth effect, our findings raise concerns about the usefulness of established indices and standard measures of the truth effect for personality and individual difference research.