Forgetting positive social feedback is difficult: ERP evidence in a directed forgetting paradigm.

Voluntary forgetting of unwanted memories is an adaptive cognitive function. However, it remains unknown how voluntary forgetting of unwanted social feedback may influence subsequent memories and evaluations, and what the underlying neurocognitive processes are. Here, we presented participants with peer photos together with feedback indicating social acceptance or rejection, followed by "remember" or "forget" instructive cues, while electroencephalograms were recorded during the experiment. We examined the Directed Forgetting (DF) effect in a recognition memory test, and tested participants' explicit and implicit attitudes toward the peers using a social evaluation task and an affect misattribution procedure (AMP). Both the memory test and the AMP were examined immediately and 3 days after the DF task so to estimate both the instant and the long-term effects of memory control. Behaviorally, immediate memory test showed smaller DF effect for positive than negative social feedback, which suggests that forgetting positive social feedback was more difficult than forgetting negative social feedback. Regarding the ERP results, although participants showed comparable frontal N2 amplitudes (reflecting inhibitory control efforts) following the instruction of forgetting positive and negative social feedback, positive feedback elicited larger late positive potential (LPP) amplitudes than negative feedback during initial encoding phase, suggesting an encoding bias for positive self-relevant information. Intriguingly, voluntary efforts to forget negative social feedback enhanced people's explicit and implicit evaluations toward the feedback senders. These findings provide new evidence for the adaptive function of memory control, which broadens the influence of voluntary forgetting in the context of social interaction and social evaluation.