Psychotropic placebos reduce the misinformation effect by increasing monitoring at test

A psychotropic placebo can help people resist the misinformation effect, an effect thought to be caused by a shift to more stringent source monitoring. When this shift occurs has been unclear. To address this issue we gave some people - but not others - a phoney cognitive-enhancing drug we called R273. Shortly afterwards, everyone took part in a misinformation effect experiment. To gather evidence about source monitoring we surreptitiously recorded time to read the misleading postevent narrative, and response time at test. Our findings suggest that people shifted to more stringent source monitoring at test. Moreover, people with higher working memory capacity (WMC) performed better than people with lower WMC - but only when they were told they had received R273, a finding that fits with research showing that WMC can confer advantages in situations demanding effortful control, but not when automatic heuristics suffice.     

Individual differences in working memory capacity affect false memories for missing aspects of events

Recently, Gerrie, Belcher, and Garry (2006) found that, when participants watch an event with parts missing, they falsely claim to have seen the missing parts—but they were more likely to claim they had seen less crucial parts than more crucial parts. Their results fit with a source-monitoring framework (SMF; Johnson, Hashtroudi, & Lindsay, 1993) explanation of false memories. In this paper we used individual differences in working memory capacity (WMC) to examine the SMF explanation of false memories for missing aspects of events. An accumulating body of research suggests that WMC is strongly related to controlling attention, including the ability to distinguish between sources of information. The primary purpose of the present study was to examine whether people with larger WMC are better able to ward off false memories for missing information than those with a smaller WMC. We showed that higher WMC reduced false recognition of crucial information, but did not change false recognition of noncrucial information. Additionally, we found that WMC had little effect on participants’ subjective experience of true and false recognition of events, regardless whether the information was crucial or not. These results provide further evidence that people's WMC is related to their source-monitoring ability.     

Psychotropic placebos create resistance to the misinformation effect

Can a placebo for a psychotropic drug help participants resist the misinformation effect? To answer this question, we gave participants a mixture of baking soda and water and told half of them that the mixture was a cognition-enhancing drug called R273 and told the other half that it was an inactive version of the drug. Shortly thereafter, all participants took part in a three-stage misinformation experiment. Compared with participants who were told that they had taken the placebo, the participants who were told that they had taken the drug reported improved cognitive abilities and were less susceptible to the misinformation effect. We provide sourcemonitoring and mindfulness accounts of our findings.     

Why Higher Working Memory Capacity May Help You Learn: Sampling,Search, and Degrees of Approximation

Algorithms for approximate Bayesian inference, such as those based on sampling (i.e., Monte Carlo methods), provide a natural source of models of how people may deal with uncertainty with limited cognitive resources. Here, we consider the idea that individual differences in working memory capacity (WMC) may be usefully modeled in terms of the number of samples, or “particles,” available to perform inference. To test this idea, we focus on two recent experiments that report positive associations between WMC and two distinct aspects of categorization performance: the ability to learn novel categories, and the ability to switch between different categorization strategies (“knowledge restructuring”). In favor of the idea of modeling WMC as a number of particles, we show that a single model can reproduce both experimental results by varying the number of particles—increasing the number of particles leads to both faster category learning and improved strategy‐switching. Furthermore, when we fit the model to individual participants, we found a positive association between WMC and best‐fit number of particles for strategy switching. However, no association between WMC and best‐fit number of particles was found for category learning. These results are discussed in the context of the general challenge of disentangling the contributions of different potential sources of behavioral variability.     

They Might Be a Liar But They’re My Liar: Source Evaluation and the Prevalence of Misinformation

Even if people acknowledge that misinformation is incorrect after a correction has been presented, their feelings towards the source of the misinformation can remain unchanged. The current study investigated whether participants reduce their support of Republican and Democratic politicians when the prevalence of misinformation disseminated by the politicians appears to be high in comparison to the prevalence of their factual statements. We presented U.S. participants either with (1) equal numbers of false and factual statements from political candidates or (2) disproportionately more false than factual statements. Participants received fact-checks as to whether items were true or false, then rerated both their belief in the statements as well as their feelings towards the candidate. Results indicated that when corrected misinformation was presented alongside equal presentations of affirmed factual statements, participants reduced their belief in the misinformation but did not reduce their feelings towards the politician. However, if there was considerably more misinformation retracted than factual statements affirmed, feelings towards both Republican and Democratic figures were reduced—although the observed effect size was extremely small.     

Individual differences in working memory capacity affect false memories for missing aspects of events

Recently, Gerrie, Belcher, and Garry (2006) found that, when participants watch an event with parts missing, they falsely claim to have seen the missing parts--but they were more likely to claim they had seen less crucial parts than more crucial parts. Their results fit with a source-monitoring framework (SMF; Johnson, Hashtroudi, & Lindsay, 1993) explanation of false memories. In this paper we used individual differences in working memory capacity (WMC) to examine the SMF explanation of false memories for missing aspects of events. An accumulating body of research suggests that WMC is strongly related to controlling attention, including the ability to distinguish between sources of information. The primary purpose of the present study was to examine whether people with larger WMC are better able to ward off false memories for missing information than those with a smaller WMC. We showed that higher WMC reduced false recognition of crucial information, but did not change false recognition of noncrucial information. Additionally, we found that WMC had little effect on participants' subjective experience of true and false recognition of events, regardless whether the information was crucial or not. These results provide further evidence that people's WMC is related to their source-monitoring ability.     

Why misinformation is more likely to be recognised over time: A source monitoring account

Although memory for actual events tends to be forgotten over time, memory for misinformation tends to be retrieved at a stable rate over long delays or at a rate greater than that found immediately after encoding. To examine whether source monitoring errors contribute to this phenomenon, two experiments investigated subjects' memory for the source of misinformation at different retention intervals. Subjects viewed a slide presentation, read a narrative containing misinformation, and, either 10 minutes or 1 week later, completed a recognition test about details seen in the slides and about the source of these details. After the longer retention interval in both experiments, participants were more likely to agree that they had seen misleading information and were also more likely to incorrectly associate the misinformation with the slide event. Theoretical implications of these findings are considered.     

Whichever way you choose to categorize, working memory helps you learn

There has been growing interest in the relationship between the capacity of a person's working memory and their ability to learn to categorize stimuli. While there is evidence that working memory capacity (WMC) is related to the speed of category learning, it is unknown whether WMC predicts which strategies people use when there are multiple possible solutions to a categorization problem. To explore the relationship between WMC, category learning, and categorization strategy use, 173 participants completed two categorization tasks and a battery of WMC tasks. WMC predicted the speed of category learning, but it did not predict which strategies participants chose to perform categorization. Thus, WMC does not predict which categorization strategies people use but it predicts how well they will use the strategy they select.     

The effect of question type on resistance to misinformation about present and absent details

The typical misinformation effect shows that accuracy is lower for details about which people received misleading compared to non-misleading (control) information. In two experiments, we examined the misinformation effect for non-witnessed details (i.e., absent). Three question types introduced control, misleading, and absent details (closed, closed-detailed, and open questions) about a mock burglary video. On this misinformation test, participants' reports of absent details were less accurate than control details only when they were introduced using open questions. Misinformation effects in a subsequent recognition test were present for misleading details in both experiments, but for absent details only in Experiment 2. Experiment 2 also revealed that participants who avoided answering open questions containing misleading and absent details had more accurate memories for these details on the subsequent recognition test than participants who answered these questions. In both experiments, confidence was lowest for absent details. Implications for theory and practice are discussed.     

Whichever way you choose to categorize,working memory helps you learn

There has been growing interest in the relationship between the capacity of a person's working memory and their ability to learn to categorize stimuli. While there is evidence that working memory capacity (WMC) is related to the speed of category learning, it is unknown whether WMC predicts which strategies people use when there are multiple possible solutions to a categorization problem. To explore the relationship between WMC, category learning, and categorization strategy use, 173 participants completed two categorization tasks and a battery of WMC tasks. WMC predicted the speed of category learning, but it did not predict which strategies participants chose to perform categorization. Thus, WMC does not predict which categorization strategies people use but it predicts how well they will use the strategy they select.     

Paradoxical effects of testing: retrieval enhances both accurate recall and suggestibility in eyewitnesses

Although retrieval practice typically enhances memory retention, it can also impair subsequent eyewitness memory accuracy (Chan, Thomas, & Bulevich, 2009). Specifically, participants who had taken an initial test about a witnessed event were more likely than nontested participants to recall subsequently encountered misinformation—an effect we called retrieval-enhanced suggestibility (RES). Here, we sought to test the generality of RES and to further elucidate its underlying mechanisms. To that end, we tested a dual mechanism account, which suggests that RES occurs because initial testing (a) enhances learning of the later misinformation by reducing proactive interference and (b) causes the reactivated memory trace to be more susceptible to later interference (i.e., a reconsolidation account). Three major findings emerged. First, RES was found after a 1-week delay, where a robust testing benefit occurred for event details that were not contradicted by later misinformation. Second, blockage of reconsolidation was unnecessary for RES to occur. Third, initial testing enhanced learning of the misinformation even when proactive interference played a minimal role.     

Planting misinformation in the human mind: a 30-year investigation of the malleability of memory

The misinformation effect refers to the impairment in memory for the past that arises after exposure to misleading information. The phenomenon has been investigated for at least 30 years, as investigators have addressed a number of issues. These include the conditions under which people are especially susceptible to the negative impact of misinformation, and conversely when are they resistant. Warnings about the potential for misinformation sometimes work to inhibit its damaging effects, but only under limited circumstances. The misinformation effect has been observed in a variety of human and nonhuman species. And some groups of individuals are more susceptible than others. At a more theoretical level, investigators have explored the fate of the original memory traces after exposure to misinformation appears to have made them inaccessible. This review of the field ends with a brief discussion of the newer work involving misinformation that has explored the processes by which people come to believe falsely that they experienced rich complex events that never, in fact, occurred.     

Recalling a Witnessed Event Increases Eyewitness Suggestibility: The Reversed Testing Effect

ABSTRACT— People's later memory of an event can be altered by exposure to misinformation about that event. The typical misinformation paradigm, however, does not include a recall test prior to the introduction of misinformation, contrary to what real-life eyewitnesses encounter when they report to a 911 operator or crime-scene officer. Because retrieval is a powerful memory enhancer (the testing effect), recalling a witnessed event prior to receiving misinformation about it should reduce eyewitness suggestibility. We show, however, that immediate cued recall actually exacerbates the later misinformation effect for both younger and older adults. The reversed testing effect we observed was based on two mechanisms: First, immediate cued recall enhanced learning of the misinformation; second, the initially recalled details became particularly susceptible to interference from later misinformation, a finding suggesting that even human episodic memory may undergo a reconsolidation process. These results show that real-life eyewitness memory may be even more susceptible to misinformation than is currently envisioned.     

Fighting the Past: Perceptions of Control,Historical Misperceptions,and Corrective Information in the Israeli‐Palestinian Conflict

What makes people deny wrongdoing that their group has inflicted on others? Prior research argues that refusing to acknowledge past misbehavior contributes to intergroup conflict, making historical misinformation important to understand and address. In particular, feeling a lack of control may make people more vulnerable to these misperceptions—a claim we test in a preregistered survey experiment examining beliefs about the Palestinian exodus during the creation of the state of Israel. Consistent with expectations, Jewish Israelis who were asked to recall an event in which they lacked control were more vulnerable to arguments (incorrectly) denying any Jewish responsibility for the exodus. By contrast, corrective information successfully reduced misperceptions regardless of feelings of control. However, corrections had no effect on attitudes toward the outgroup or support for the peace process, which suggests that historical misperceptions may be more of a symptom of intergroup conflict than a cause of its persistence.     

Comparison of neural activity that leads to true memories,false memories,and forgetting: An fMRI study of the misinformation effect

False memories can occur when people are exposed to misinformation about a past event. Of interest here are the neural mechanisms of this type of memory failure. In the present study, participants viewed photographic vignettes of common activities during an original event phase (OEP), while we monitored their brain activity using fMRI. Later, in a misinformation phase, participants viewed sentences describing the studied photographs, some of which contained information conflicting with that depicted in the photographs. One day later, participants returned for a surprise item memory recognition test for the content of the photographs. Results showed reliable creation of false memories, in that participants reported information that had been presented in the verbal misinformation but not in the photographs. Several regions were more active during the OEP for later accurate memory than for forgetting, but they were also more active for later false memories, indicating that false memories in this paradigm are not simply caused by failure to encode the original event. There was greater activation in the ventral visual stream for subsequent true memories than for subsequent false memories, however, suggesting that differences in encoding may contribute to later susceptibility to misinformation.     

The effects of conformity on recognition judgements for emotional stimuli

Exposure to another’s account of a shared event can influence the content of an individual’s memory report. We examine whether the emotionality of the to-be-remembered information influences the likelihood that socially encountered post-event information is accepted into memory. Participants were exposed to positive, negative or neutral emotional pictures. Subsequently, they had to discriminate these pictures from new pictures in a ‘yes/no’ recognition decision either before or subsequent to a confederate providing misinformation, accurate or no information. Post-event information influenced participants’ responding in the recognition test. Effects were larger for participants viewing neutral items and persisted for these items on a subsequent private source monitoring test. These findings indicate that people rely more on information from others when encountering non-emotional compared to emotional items. We suggest that increased memory strength in conjunction with access to strong retrieval cues in the recognition test serves to shield emotional items from vulnerability to effects of memory conformity.     

Advertising's misinformation effect

This research explores whether post-experience advertising alters information learned in a consumer's direct experience. An advertising misinformation effect was obtained for colour memory of a previously seen candy bar wrapper upon both visual and verbal misinformation. However, the misleading visual information produced more ‘remember’ judgements than misleading verbal information. This advertising misinformation effect did not dissipate when the source was discredited. We found that such memory changes can be directly linked to consumer subjective judgements and choices when the misleading information is particularly salient. Not only do these findings constitute a novel generalizability of the misinformation effect, they also have implications for social policy research on deceptive advertising. Copyright © 1998 John Wiley & Sons, Ltd.     

Creating new memories that are quickly accessed and confidently held

In two experiments involving a total of 542 subjects, a series of slides depicting a burglary was shown. After the initial event, subjects were exposed to one or more narratives about the event that contained some misinformation or neutral information about four critical details. Finally, subjects were tested on their memories of what they saw, and their reaction times and confidence levels were measured. When subjects took a standard test in which the misinformation item was a possible response option, they responded very quickly and confidently when making this incorrect choice. Misled subjects responded as quickly and confidently to these "unreal" memories as they did to their genuine memories. It does not seem, then, that the misinformation effect arises from a large proportion of subjects who must resolve a conflict between two memories when they are tested, a conflict that would be expected to take time. When subjects took a modified test in which the misinformation item was not a possible response, misled subjects were as accurate as were controls, but they responded more slowly, regardless of whether they ultimately chose the right or wrong option. These findings indicate that misinformation does introduce some form of interference not detected by a simple test of accuracy.     

A Developmental Evaluation of Frequency Memory for Actions Presented in Lists,Scripts, and Stories

Although some research suggests that misinformation provided by a co-witness could be more influential than that obtained from other sources, most of this research has compared the effect of co-witness information against non-social forms of misinformation only. To better understand the influence of co-witnesses we compared the influence of co-witness misinformation with the influence of misinformation provided by an interviewer. Across two experiments using the MORI paradigm we found no evidence that a co-witness is particularly influential relative to another social source of post-event misinformation. In fact, the source of the misinformation delivered by our interviewer was less likely to be correctly recalled than the source of the misinformation delivered by a co-witness. There was some evidence that misinformation delivered by both a co-witness and an interviewer has a stronger effect on witnesses' accuracy and confidence than misinformation obtained from either source alone. Finally, our results suggest that the opportunity to provide an early individual memory account might protect against the effect of subsequently-encountered co-witness misinformation. These results have important implications for the way that criminal investigations are conducted.     

Not wallowing in misery – retractions of negative misinformation are effective in depressive rumination

People often continue to rely on misinformation in their reasoning after they have acknowledged a retraction; this phenomenon is known as the continued-influence effect. Retractions can be particularly ineffective when the retracted misinformation is consistent with a pre-existing worldview. We investigated this effect in the context of depressive rumination. Given the prevalence of depressotypic worldviews in depressive rumination, we hypothesised that depressive rumination may affect the processing of retractions of valenced misinformation; specifically, we predicted that the retraction of negative misinformation might be less effective in depressive ruminators. In two experiments, we found evidence against this hypothesis: in depressive ruminators, retractions of negative misinformation were at least as effective as they were in control participants, and more effective than retractions of positive misinformation. Findings are interpreted in terms of an attentional bias that may enhance the salience of negative misinformation and may thus facilitate its updating in depressive rumination.