The Trajectory of Truth: A Longitudinal Study of the Illusory Truth Effect

Emma L Henderson; Daniel J Simons; Dale J Barr

doi:10.5334/joc.161

The Trajectory of Truth: A Longitudinal Study of the Illusory Truth Effect

J Cogn. 2021 Jun 8;4(1):29. doi: 10.5334/joc.161.

Authors

Emma L Henderson^{1

2}, Daniel J Simons³, Dale J Barr⁴

Affiliations

¹ Faculty of Business and Social Sciences, Kingston University, Kingston Hill Campus, Kingston Hill, Kingston upon Thames, KT2 7LB, UK.
² School of Psychology, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
³ Department of Psychology, University of Illinois at Urbana-Champaign, US.
⁴ Institute of Neuroscience & Psychology, University of Glasgow, UK.

PMID: 34164597
PMCID: PMC8194981
DOI: 10.5334/joc.161

Abstract

Repeated statements are rated as subjectively truer than comparable new statements, even though repetition alone provides no new, probative information (the illusory truth effect). Contrary to some theoretical predictions, the illusory truth effect seems to be similar in magnitude for repetitions occurring after minutes or weeks. This Registered Report describes a longitudinal investigation of the illusory truth effect (n = 608, n = 567 analysed) in which we systematically manipulated intersession interval (immediately, one day, one week, and one month) in order to test whether the illusory truth effect is immune to time. Both our hypotheses were supported: We observed an illusory truth effect at all four intervals (overall effect: χ ²(1) = 169.91; M _repeated = 4.52, M _new = 4.14; H1), with the effect diminishing as delay increased (H2). False information repeated over short timescales might have a greater effect on truth judgements than repetitions over longer timescales. Researchers should consider the implications of the choice of intersession interval when designing future illusory truth effect research.

Keywords: Registered Report; illusory truth; longitudinal; repetition; truth judgement.

Grants and funding

ELH was funded by a PhD studentship from Kingston University. This work was supported by an EASP Pre-registered Research Grant, and PhD research funds from Kingston University and Cardiff University awarded to ELH.