Sharing traumatic experiences: earlier denial increases endorsement of misinformation from a co-witness

People oftentimes experience traumatic events together with co-witnesses, who might remember incidents differently. Moreover, people experiencing such traumatic events may initially deny them but eventually come forward (e.g. to a co-witness). We examined how initial false denials affected participants' endorsement of misinformation from a co-witness. Participants (N = 131) watched a trauma analogue video. Next, half were instructed to falsely deny seeing certain details in the video, whereas the other half responded honestly in an interview with the experimenter. After one week, participants discussed the video with a co-witness (confederate) who suggested misinformation. Finally, all participants' memory for the interview and video were tested. Participants who initially denied were more likely to accept co-witness misinformation than honest participants. False denials were also related to increased omission errors regarding the interview, but not the video. Thus, even though false denials might increase endorsement of some misinformation, memory for core details might remain unaffected.