Stealing and sharing memories: Source monitoring biases following collaborative remembering

People experience difficulties tracking the source of their memories following collaborative remembering. This results in a variety of source monitoring errors. Researchers have typically focused on one of these errors - instances of adopting information from external sources as one's own memories. They have failed to investigate the frequency of other possible source monitoring errors. Because of this, it is impossible to say whether observed instances of mistakenly adopting external information represent a true bias in remembering or whether these errors simply reflect one of many memory errors that have an equal likelihood of occurring. In two studies, we teased apart these two possibilities. Members of dyads individually studied pictures with some items appearing in both participants' pictures and some unique to each one's pictures. Participants then collaboratively recalled what items were present. After the collaborative recall, participants completed individual source monitoring tests. We found that participants displayed biases in their source monitoring errors for information discussed during collaborative remembering. They were more likely to adopt information from partners as their own memories than attribute their contributions to their partners. They also more often believed their memories (rather than their partner's) were shared, representing a false consensus. Importantly, these biases only occurred following collaborative remembering and not when individuals received comparable information in a non-social setting. These results illuminate the importance of investigating the relative, and not just absolute, frequency of source monitoring errors and provide insight into how collaborative remembering changes individual memories over time.