Warning before misinformation exposure modulates memory encoding.

Exposure to misleading information after witnessing an event can impair future memory reports about the event. This pervasive form of memory distortion, termed the misinformation effect, can be significantly reduced if individuals are warned about the reliability of post-event information before exposure to misleading information. The present fMRI study investigated whether such prewarnings improve subsequent memory accuracy by influencing encoding-related neural activity during exposure to misinformation. We employed a repeated retrieval misinformation paradigm in which participants watched a crime video (Witnessed Event), completed an initial test of memory, listened to a post-event auditory narrative that contained consistent, neutral, and misleading details (Post-Event Information), and then completed a final test of memory. At the behavioral level, participants who were given a prewarning before the Post-Event Information were less susceptible to misinformation on the final memory test compared with participants who were not given a warning (Karanian et al., Proceedings of the National Academy of Sciences of the United States of America, 117, 22771-22779, 2020). This protection from misinformation was accompanied by greater activity in frontal regions associated with source encoding (lateral PFC) and conflict detection (ACC) during misleading trials as well as a more global reduction in activity in auditory cortex and semantic processing regions (left inferior frontal gyrus) across all trials (consistent, neutral, misleading) of the Post-Event Information narrative. Importantly, the strength of these warning-related activity modulations was associated with better protection from misinformation on the final memory test (improved memory accuracy on misleading trials). Together, these results suggest that warnings modulate encoding-related neural activity during exposure to misinformation to improve memory accuracy.