Investigating features that contribute to evaluations of intrusiveness for thoughts and memories.

What makes a thought feel intrusive? One possibility is that traumatic experiences are the primary cause of intrusive thoughts and memories. Another possibility is that experiences of intrusiveness arise from the features involved with re-experiencing. We investigated several features that may lead a thought to feel intrusive: task-congruence, repetition, and affective content. In Experiment 1, participants listened to popular song clips expected to become stuck in one's head. In Experiment 2, participants were cued to recall their own autobiographical memories. We found that both songs and autobiographical memories replaying mentally felt more intrusive when they were incongruent with the current task, cued repeatedly, and had negative emotional content. Additionally, even liked songs and positive autobiographical memories were evaluated as highly intrusive under some conditions. Based on these findings, we argue that intrusiveness is not limited to traumatic thoughts, but rather is a context-dependent evaluation influenced by a variety of features.

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.

Truthiness, the illusory truth effect, and the role of need for cognition.

Ease of processing-cognitive fluency-is a central input in assessments of truth, but little is known about individual differences in susceptibility to fluency-based biases in truth assessment. Focusing on two paradigms-truthiness and the illusory truth effect-we consider the role of Need for Cognition (NFC), an individual difference variable capturing one's preference for elaborative thought. Across five experiments, we replicated basic truthiness and illusory truth effects. We found very little evidence that NFC moderates truthiness. However, we found some evidence that (without an experimental warning), people high on NFC may be more susceptible to the illusory truth effect. This may reflect that elaborative thought increases the fluency with which encoded statements are processed after a delay (thus increasing the illusory truth effect). Future research may fruitfully test whether the influence of NFC and other individual difference measures depends on whether people are making immediate or delayed truth judgments.