What can we remember after complex denials? The impact of different false denials on memory

False denial is a deceptive strategy that requires fewer cognitive resources than other strategies (e.g. simulating amnesia, fabrication). In the present experiment, we examined the effects of different types of false denials varying in cognitive load on memory. Participants (N = 159) watched a video (theft) and then answered some questions about it. Some participants had to tell the truth about the theft, while others were either asked to falsely deny all the event-related details (i.e. simple false denial) or to falsely deny just some details of the same event (i.e. complex false denial). After two days, all participants completed a memory task in which they truthfully recognized whether details were (i) discussed during the interview or (ii) seen in the video. Additionally, recall scores (i.e. correct details, omissions, commissions) of the memory for the event were assessed. Participants who falsely denied all details reported a higher memory impairment for the interview than the other groups. Interestingly, liars who were engaged in complex denying had the largest memory impairment for the event and reported more commissions than those in the simple false denial group. This experiment shows that under certain conditions, memory is increasingly impaired for high cognitive load lies.