Contamination or natural variation? A comparison of contradictions from suggested contagion and intrinsic variation in repeated autobiographical accounts

Contradictions and other changes across retellings can result from contamination from others, deception, or natural variation. In this study we used the social contagion paradigm to investigate (a) the relative frequencies and types of contradictions resulting from outside suggestion and from natural variation, and (b) a baseline measure of variation in autobiographical memory accounts across retellings. Participants recalled memories of four personal events. One week later, participants and confederates alternated in describing their own and summarising each other's autobiographical events. The confederates included a contradictory contagion detail in two of the participants’ events. The participants then individually recalled their own events. Twenty percent of participants made contradictions due to contagion, but 63% of participants made contradictions due to intrinsic variation. Accounts also exhibited other forms of variation. Concern about negative evaluation and social closeness ratings predicted contradictions due to contagion but not intrinsic variation. We discuss applications to forensic settings.