The Effect of Plausibility and Suggested Event Frequency on the Implantation of False Beliefs and Memories

We examined how event plausibility and suggested frequency influence the formation of false beliefs and memories using a blind implantation paradigm. Participants (N = 855) rated 20 events (two critical, high vs. low plausible) for experience and frequency. One week later, 103 participants (Mage = 33.7; 62.1% women) who had not reported the critical events received a follow-up survey suggesting they indicated experiencing four true and one false event (once or repeatedly), rating event belief and recollection before and after imagination. The high plausible event elicited higher false beliefs than the low plausible event under suggested single, not repeated experiences, with no statistically significant effect of imagination. False memory ratings did not differ by plausibility or suggested frequency pre-imagination. False beliefs and memories ranged from 9.1% (low plausible repeated) to 52% (high plausible single). These findings emphasize how factors such as suggested frequency differentially shape false belief and memory formation.