Department of Psychology and Behavioural Sciences

In two experiments, we examined how accurately participants remembered details from a naturalistic, first-person perspective film, which ended with the protagonist either encountering or not encountering an unexpected detail. Participants who watched the film with the unexpected detail at the end displayed superior accuracy for preceding event details compared to those who watched a film without such a detail. This retroactive enhancement effect generalized across both visual and auditory details, but it appeared contingent upon the unexpected detail being relevant to the event's story. The effect occurred whether participants’ memory was tested immediately or after a two-day delay. The present findings can be seen as consistent with prior work on synaptic tagging and long-term potentiation, but the phenomenon of retroactive enhancement has not been demonstrated previously for naturally unfolding events. Implications of the findings are discussed in relation to eyewitness memory and intrusive memories in post-traumatic stress disorder.