Complex lying leads to more memory impairments in daily life

Previous studies have demonstrated that lying can undermine memory and that its memory-undermining effects could be modulated by the cognitive resources required to tell a lie. We extended the investigation of the memory-undermining effect by using a daily life setting in which participants were highly involved in a mock shopping task. Participants were randomly assigned to truth-telling, simple lying or complex lying conditions. After finishing the shopping task, participants were told that two people wanted to know about their shopping lists and would ask them some questions in an interview. In answering the interview questions, the truth-telling group was asked to respond honestly, the simple lying group was asked to give denial responses, and the complex lying group was required to respond deceptively. The item memory test, source memory test and destination memory test were given in an orderly manner 48 hours after the interview. We found that the complex lying group, rather than the simple lying group, forgot the lies they told in the interview and mistakenly believed they had lied about something that they had not lied about. Moreover, the complex lying group retained fewer memories about the person they responded to than the honest group. In addition, participants in the complex lying group had more nonbelieved memories than those in the truth-telling group in both item and source memory tests. We conclude that complex lying that requires more cognitive resources could result in more memory impairments in daily life.