"That's just like, your opinion, man": the illusory truth effect on opinions.

With the expanse of technology, people are constantly exposed to an abundance of information. Of vital importance is to understand how people assess the truthfulness of such information. One indicator of perceived truthfulness seems to be whether it is repeated. That is, people tend to perceive repeated information, regardless of its veracity, as more truthful than new information, also known as the illusory truth effect. In the present study, we examined whether such effect is also observed for opinions and whether the manner in which the information is encoded influenced the illusory truth effect. Across three experiments, participants (n = 552) were presented with a list of true information, misinformation, general opinion, and/or social-political opinion statements. First, participants were either instructed to indicate whether the presented statement was a fact or opinion based on its syntax structure (Exp. 1 & 2) or assign each statement to a topic category (Exp. 3). Subsequently, participants rated the truthfulness of various new and repeated statements. Results showed that repeated information, regardless of the type of information, received higher subjective truth ratings when participants simply encoded them by assigning each statement to a topic. However, when general and social-political opinions were encoded as an opinion, we found no evidence of such effect. Moreover, we found a reversed illusory truth effect for general opinion statements when only considering information that was encoded as an opinion. These findings suggest that how information is encoded plays a crucial role in evaluating truth.

Factors affecting the forced confabulation effect: a meta-analysis of laboratory studies.

During police investigations, interviewees are sometimes forced to confabulate a response to questions for which they don't know the answer. In this registered report, we conducted a three-level meta-analysis to examine whether forcing people to confabulate an answer to these questions can lead to false memories for the confabulated details and/or events (i.e., forced confabulation effect). Results showed that forced confabulation indeed led to the production of false memories. Qualitative reviews of studies suggested that the forced confabulation effect is enhanced after receiving confirmatory feedback. Moreover, we found evidence that longer delays between the forced confabulation phase and the final memory task are necessary to observe the forced confabulation effect for entire events. However, caution is needed when interpreting the forced confabulation effect. Specifically, our moderator analyses revealed that voluntarily produced confabulation led to more false memories than forced confabulation. Also, our exploratory analysis indicated that the forced confabulation effect was mainly observed in within-subject designs. Taken together, our meta-analysis supports the notion that forcing participants to confabulate can lead them to later report such confabulations as part of the truth. Nonetheless, caution is warranted because this effect might be due to the introduction of misinformation through asking unanswerable questions.

The importance of the smallest effect size of interest in expert witness testimony on alcohol and memory.

Memory experts are sometimes asked to evaluate the validity of accounts of witnesses, victims, or suspects. In some of these cases, they are asked what effect alcohol has on the validity of such accounts. In this article, we offer a guide on what expert witnesses can reliably say about how alcohol affects memory. We do so by resorting to effect sizes from previous studies and meta-analytic work, and address this novel question: Are these effect sizes meaningful in legal cases? More specifically, we argue that any determination of whether individual studies about alcohol and memory are practically relevant for legal cases, scientists must focus on the smallest effect size of interest. We make the case that a decrease or increase of only 1 detail, especially an incorrect detail, should be regarded as the smallest effect size of interest in this line of research. In line with this idea, we show that effect sizes in the alcohol and memory literature are often larger than this smallest effect size of interest. This finding is important because it implies that alcohol often exerts a practically relevant and meaningful detrimental effect on the reporting of both correct and incorrect details, which in turn negatively affects the validity of witness testimony.

Do liars really remember what they lied upon? The impact of fabrication on memory.

The present experiment aimed to examine how fabrication can affect memory. In particular, we examined whether different types of fabrication can lead to different mnemonic effects. A sample of 159 participants watched a video of a robbery and subsequently answered some questions about it. Participants were divided into three conditions: one group was instructed to tell the truth (i.e., truth-telling group), while the other two groups were instructed to lie either by partially distorting details (i.e., distortion group) or by completely making up wrong details of the event seen in the video (i.e., fabrication group). Two days later, participants completed a final memory test where they honestly answered recognition and recall questions concerning: (i) memory for the video and (ii) memory for having discussed details during the interview. Results showed that different types of fabrication affect liars' memory differently. Fabricators reported an undermining of memory for the event, whereas those who partially distorted details reported a higher impairment for the interview. Our findings showed that the effects of lying on liars' memory might be determined by the cognitive resources required to lie.

Adopting a fictitious autobiography: fabrication inflation or deflation?

In the present experiment, we examined whether adopting a fictitious biography would make participants believe in this autobiography. Participants were split up into two conditions: forced confabulation condition and control condition. The forced confabulation condition received a snippet with the fake biography and had to adopt it through several methods (i.e., method acting, journaling, and convincing experimenters in an interview) over an extended period of time. The control condition was told that they partook in an experiment about personal childhood memories. Before, during and after lying participants completed four Life Event Inventories (LEI). Results revealed that after coming forward with the truth participants did not increase nor decrease their belief for the lied about events. Additionally, even after a one-year delay, we found no evidence for either effect. Our findings suggest that more extreme forms of fabrication do not make people believe in their lies.