How eyewitnesses resist misinformation: Social postwarnings and the monitoring of memory characteristics

Previous findings have been equivocal as to whether the postevent misinformation effect on eyewitness memory is reduced by warnings presented after the misinformation (postwarnings). In the present research, social postwarnings, which characterize the postevent source as a low-credibility individual, diminished the misinformation effect in both cued recall and recognition tests. Discrediting the source as being either untrustworthy or incompetent was effective (Experiment 1). Also, postwarned participants rated reality characteristics of their memories more accurately than did participants receiving no or high-credibility information about the postevent source (Experiment 2). A social postwarning yielded the same results as an explicit source-monitoring appeal and led to longer response times for postevent items, relative to a no-warning condition (Experiments 3 and 4). The findings suggest that the reduced misinformation effect was due to more thorough monitoring of memory characteristics by postwarned participants, rather than to a stricter response criterion or to enhanced event memory.     

Relative - not absolute - judgments of credibility affect susceptibility to misinformation conveyed during discussion

People remember different details about the same events, and when they discuss events they exchange new – and misleading – information. Discussion can change memory, especially when the source of new information is highly credible. But we do not know whether the effects of credibility are based on absolute judgments – judging a source's credibility independently from our own credibility – or relative judgments – judging a source's credibility only in relation to our own credibility. We addressed this question by manipulating subjects' expectations, leading them to believe that they either had the same, higher or lower “visual acuity” than their partner while they watched a movie together. To create ample opportunities for the pairs to mention misleading details to one another, each member unknowingly saw a different version of the movie. The pairs then discussed some of the critical differences, but not others. Later, everyone took an independent recognition test. Subjects' susceptibility to misinformation depended on their own credibility relative to their partner's, supporting the idea that susceptibility to misinformation depends on relative differences in credibility.     

Repetition of previously novel melodies sometimes increases both remember and know responses in recognition memory

Recognition memory for previously novel melodies was tested in three experiments in which subjects usedremember andknow responses to report experiences of recollection, or of familiarity in the absence of recollection, for each melody they recognized. Some of the melodies were taken from Polish folk songs and presented vocally, but without the words. Others were taken from obscure pieces of classical music, presented as single-line melodies. Prior to the test, the melodies were repeated for varying numbers of study trials. Repetition of the Polish melodies increased both remember and know responses, while repetition of classical melodies increased remember but not know responses. When subjects were instructed to report guesses, guess responses were inversely related to remember and know responses and there were more guesses to lures than to targets. These findings establish that remembering and knowing are fully independent functionally and, by the same token, they provide further evidence against the idea that response exclusivity causes increases in remembering to force decreases in knowing. The findings also suggest that simultaneous increases in remembering and knowing occurred because the Polish melodies came from a genre for which the subjects had relatively little previous experience.     

The illusion of knowledge: When more information reduces accuracy and increases confidence

Intuition suggests that having more information can increase prediction accuracy of uncertain outcomes. In four experiments, we show that more knowledge can decrease accuracy and simultaneously increase prediction confidence. Participants were asked to predict basketball games sampled from a National Basketball Association season. All participants were provided with statistics (win record, halftime score), while half were additionally given the team names. Knowledge of names increased the confidence of basketball fans consistent with their belief that this knowledge improved their predictions. Contrary to this belief, it decreased the participants’ accuracy by reducing their reliance on statistical cues. One of the factors contributing to this underweighting of statistical cues was a bias to bet on more familiar teams against the statistical odds. Finally, in a real betting experiment, fans earned less money if they knew the team names while persisting in their belief that this knowledge improved their predictions.     

The effects of state anxiety on the suggestibility and accuracy of child eyewitnesses

The negative effect of misleading information on memory is a well‐established fact in eyewitness testimony. However, individual differences have rarely been studied in this context, particularly in children. This paper is one of the first to explore whether objectively measured state anxiety levels have a moderating influence on suggestibility. A group of 83 9–10‐year‐old schoolchildren took part in the experiment. They were tested on their recall of details surrounding a minor car accident shown on video. No effects of state anxiety on accuracy were found. Clear misleading information effects were found, however (p < 0.001). Furthermore, both analysis of covariance and Pearson's correlation coefficients showed that higher anxiety levels were associated with a reduction in the number of misled responses given by the misinformed participants relative to low‐anxious participants (p < 0.05). The theoretical relevance of these findings are discussed in the light of processing efficiency theory and the ‘affect as information’ hypothesis. The practical implications for children as witnesses are also considered. Copyright © 2002 John Wiley & Sons, Ltd.     

The effects of the age of eyewitnesses on the accuracy and suggestibility of their testimony

Previous studies have compared the performance of young adult eyewitnesses with that of children or elderly eyewitnesses, but few studies have allowed direct comparison of the performance of all three age groups. The accuracy and suggestibility of accounts of a video recording of a kidnapping were investigated using an experimental eyewitness paradigm. Subjects were drawn from three age groups: children (aged 7–9 years); young adults (aged 16–18 years) and elderly subjects (aged 60–85 years). Subjects' accuracy in answering non-misleading questions and their susceptibility to misleading information was measured. Both the elderly and child subjects gave fewer correct answers and more incorrect answers to non-misleading questions than did young adults. The elderly subjects gave fewer correct responses but also fewer incorrect responses to non-misleading questions than did child subjects. Children were more suggestible than either elderly or young adults. No significant difference was found in the suggestibility of elderly and young adults. Contrary to the trace strength hypothesis no relationship was found between accuracy of recall and suggestibility. © 1997 John Wiley & Sons, Ltd.     

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.     

The detrimental effects of power on confidence, advice taking, and accuracy

Incorporating input from others can enhance decision quality, yet often people do not effectively utilize advice. We propose that greater power increases the propensity to discount advice, and that a key mechanism explaining this effect is elevated confidence in one’s judgment. We investigate the relationships across four studies: a field survey where working professionals rated their own power and confidence and were rated by coworkers on their level of advice taking; an advice taking task where power and confidence were self-reported; and two advice taking experiments where power was manipulated. Results consistently showed a negative relationship between power and advice taking, and evidence of mediation through confidence. The fourth study also revealed that higher power participants were less accurate in their final judgments. Power can thus exacerbate the tendency for people to overweight their own initial judgment, such that the most powerful decision makers can also be the least accurate.     

Processes leading to confidence and accuracy in sentence recognition: a metamemory approach

We propose that memory confidence is based on the processes and products of the just-completed memory task, along with the participants' metamemory beliefs about the relation of these processes and products to memory accuracy. We tested this metamemory approach to confidence by having participants carry out a simple recognition memory task with deceptive and nondeceptive items. The deceptive items were sentences that contained a possible synonym substitution, thus allowing errors based on gist memory. For nondeceptive items, high confidence was associated with high accuracy. For deceptive items the relationship reversed; high confidence was associated with low accuracy. A memory process questionnaire was developed that provided more differentiated phenomenal reports than the traditional know/remember distinction. For nondeceptive items, metamemory beliefs tended to be valid indicators of accuracy, but for deceptive items involving unconscious reconstructive memory processes, they tended to be invalid indicators of memory accuracy. The overall results lend strong support for our metamemory approach to memory confidence.     

Processes leading to confidence and accuracy in sentence recognition: A metamemory approach

We propose that memory confidence is based on the processes and products of the just-completed memory task, along with the participants’ metamemory beliefs about the relation of these processes and products to memory accuracy. We tested this metamemory approach to confidence by having participants carry out a simple recognition memory task with deceptive and nondeceptive items. The deceptive items were sentences that contained a possible synonym substitution, thus allowing errors based on gist memory. For nondeceptive items, high confidence was associated with high accuracy. For deceptive items the relationship reversed; high confidence was associated with low accuracy. A memory process questionnaire was developed that provided more differentiated phenomenal reports than the traditional know/remember distinction. For nondeceptive items, metamemory beliefs tended to be valid indicators of accuracy, but for deceptive items involving unconscious reconstructive memory processes, they tended to be invalid indicators of memory accuracy. The overall results lend strong support for our metamemory approach to memory confidence.     

The role of individual differences in the accuracy of confidence judgments

Generally, self-assessment of accuracy in the cognitive domain produces overconfidence, whereas self-assessment of visual perceptual judgments results in underconfidence. Despite contrary empirical evidence, in models attempting to explain those phenomena, individual differences have often been disregarded. The authors report on 2 studies in which that shortcoming was addressed. In Experiment 1, participants (N= 520) completed a large number of cognitive-ability tests. Results indicated that individual differences provide a meaningful source of overconfidence and that a metacognitive trait might mediate that effect. In further analysis, there was only a relatively small correlation between test accuracy and confidence bias. In Experiment 2 (N = 107 participants), both perceptual and cognitive ability tests were included, along with measures of personality. Results again indicated the presence of a confidence factor that transcended the nature of the testing vehicle. Furthermore, a small relationship was found between that factor and some self-reported personality measures. Thus, personality traits and cognitive ability appeared to play only a small role in determining the accuracy of self-assessment. Collectively, the present results suggest that there are multiple causes of miscalibration, which current models of over- and underconfidence fail to encompass.     

Mental reinstatement of the misinformation context and the misinformation effect in children and adults

The present study investigated the effects of mental reinstatement of the context in which misleading information about an event was presented on later recognition memory for the event. Five‐year‐olds, 7‐year‐olds and adults were shown a short video depicting a children's adventure and were asked a set of misleading questions to introduce misinformation one week later. Before the recognition memory test was administered another week later, half of the participants were given instructions to mentally reinstate the context of the misleading interview. Memory was assessed with a set of forced‐choice recognition questions once in the misleading interview context and for the children a second time at home one week later. When participants were instructed to mentally reinstate the context of the misleading interview prior to the recognition test, false memory reports occurred more often for adults than for children and had a stronger impact on peripheral information than on central information for both 7‐year‐olds and adults. When 5‐ and 7‐year‐olds were tested at home, false memory reports decreased. Thus, reinstating the context of an interview introducing misinformation can reduce the accuracy of memory reports; the context dependence of both accurate and inaccurate memory reports in children and adults is discussed. Copyright © 2003 John Wiley & Sons, Ltd.     

Effects of alternating set for speed or accuracy on response time,accuracy and confidence in a unidimensional discrimination task

Three approaches to a theoretical analysis of confidence judgments are considered: one linking confidence to the number of sensory observations, one based on a distinction between ‘state’ and ‘process’ factors, and a ‘balance of evidence’ hypothesis developed from an accumulator model of discrimination. An experiment is described in which observers were asked to decide which of two parallel lines was the longer, and to rate their confidence in each judgment. Each observer's set for speed or accuracy was manipulated over successive blocks of trials, and effects on response time, accuracy, and confidence were examined. Under an accuracy set, observers produced a higher percentage of correct responses, had longer response times, and made more confident judgments than under a set for speed. Within both speed and accuracy blocks, however, confidence ratings were inversely related to response time. The data on response accuracy, time, and confidence indicate certain deficiencies in either of the first two approaches, but were well accounted for by the third.     

"With a little help from my friends...": the role of co-witness relationship in susceptibility to misinformation

Inaccuracies in eyewitness accounts can occur when witnesses are exposed to post-event misinformation via discussion with a co-witness. The current study examined the role of co-witness relationship by comparing the memory performance of pairs of romantic couples, friends and previously unacquainted strangers with that of individuals. Ninety-six participants viewed an event and then discussed the witnessed event with a stranger, a romantic partner or a friend. One member of each pair saw a theft take place during the witnessed event. Individual group participants did not discuss the witnessed event with anyone. Results indicate that all co-witness dyads produced less accurate recall accounts than participants who did not interact with another witness. However, witnesses who were previously acquainted with their co-witness (either in a friendship or romantic relationship) were significantly more likely to report information obtained from their co-witness that they had not seen themselves. Prior acquaintance also led to an increased number of incorrect attributions of both guilt and innocence.     

The influence of lawyers' questions on witness accuracy,confidence, and reaction times and on mock jurors' interpretation of witness accuracy

Two studies demonstrate the influence of lawyers' complex questions on mock‐witness accuracy, confidence, and reaction times and on the interpretation of witness accuracy by mock jurors. In study one, 32 mock witnesses were shown a short film and then questioned either with lawyers' complex questions or simple alternatives. In Study 2, 20 mock jurors viewed video footage of the mock witnesses assigned to each of the two previous conditions and were asked to rate their confidence in the witnesses' answers. The findings of the two studies indicated that lawyers' use of confusing questions reduce not only accuracy but also speed of response and both witnesses' and jurors' ability to determine accuracy. The implication of these findings is straightforward, lawyers should ask simple questions wherever possible. Copyright © 2010 John Wiley & Sons, Ltd.     

Trace‐strength and source‐monitoring accounts of accuracy and metacognitive resolution in the misinformation paradigm

Two experiments are reported that investigate the impact of misinformation on memory accuracy and metacognitive resolution. In Experiment 1, participants viewed a series of photographs depicting a crime scene, were exposed to misinformation that contradicted details in the slides, and later took a recognition memory test. For each answer, participants were required to indicate whether they were willing to testify (report) their answer to the Court and to rate confidence. Misinformation impaired memory accuracy but it had no effect on resolution, regardless of whether resolution was indexed with confidence‐rating measures (γ correlation and mean confidence) or a report‐option measure (type‐2 discrimination: d′). In Experiment 2, a similar accuracy‐confidence dissociation was found, and the misinformation effect occurred mostly with fine‐grained responses, suggesting that responding was based on recollected details. We argue that the results support source‐monitoring (SM) accounts of accuracy and resolution rather than accounts based on trace strength. Copyright © 2010 John Wiley & Sons, Ltd.     

The effects of confederate influence and confidence on the accuracy of crime judgements

Building on recent work which has investigated social influences on memory and remembering, the present experiment examined the effects of social pressure and confederate confidence on the accuracy and confidence of eyewitnesses. Sixty undergraduate participants watched a video of a staged mugging and then answered questions about the video out loud in the presence of either one or three confederates who had also watched the film with them. Unbeknownst to the participant, the confederate(s) always gave incorrect responses to four out of the eight questions. Participants and confederates were also asked to give confidence scores out loud for each of their answers. Again, unbeknownst to the participant, the confederate(s) always expressed either high or low confidence scores for the incorrect information, depending on condition. Participants gave fewer correct answers, and were less confident, in the presence of three, as opposed to one, confederates. Participants were also more confident, yet no more accurate, when the confederate(s) gave high, as opposed to low, confidence scores. Thus the presumed independence of evidence given by multiple witnesses cannot be safely assumed.     

The P3 component of the ERP reflects conscious perception, not confidence

Consistent with numerous electrophysiological studies, we recently reported that conscious perception is associated with a widely distributed modulation of the P3 component (Lamy, Salti, & Bar-Haim, 2009). We also showed that correct objective performance in the absence of subjective awareness is associated with a spatially more restricted modulation of the P3. The relatively late occurrence of the P3 along with lack of control for post-perceptual processes suggests that this component might reflect processes related to stimulus evaluation or confidence rather than to visual awareness or objective performance. The main aim of the current study was to test this hypothesis. While EEG was recorded, participants performed a forced-choice localization task and reported their subjective perception of the target on a 3-level scale that also indexed their confidence. The results showed that our previous findings are replicated when confidence is controlled for.     

Repetition effects in associative false recognition: Theme-based criterion shifts are the exception, not the rule

Previous reports have demonstrated that false memory for the critical items of associative lists decreases when lists are studied multiple times (Benjamin, 2001). In three experiments, we explored two hypotheses that might account for false memory reductions with repetition. Under an identification hypothesis, repetition decreases false memory because participants realise that critical items are absent from the list at encoding and thus reject them at test. Under a criterion shift hypothesis, repetition decreases false memory because it increases the discriminability of studied words from lures, causing participants to set a higher response criterion for positive recognition responses. Results uniquely supported the criterion shift hypothesis. Furthermore, results showed that participants only changed their criterion on separate recognition tests, not on an item-by-item basis within a single recognition test. The failure to establish separate criteria within a test increased false memory for repeated lists.