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.     

Assessing the effectiveness of warnings and the phenomenological characteristics of false memories

The phenomenology of false memories was investigated in three experiments in which participants heard two experimenters read lists of items that were related to critical nonpresented items. In Experiments 1, following a recognition memory test, participants rated the phenomenological characteristics of their memories immediately and after a 48-hour delay. False recognition was prevalent and on several dimensions participants rated their true memories as more vivid than their false memories. In Experiments 2 and 3, following the study phase, participants were warned about the phenomenological differences between true and false memories and were instructed to use this information to avoid reporting nonpresented items. This type of warning was ineffective at reducing false recall (Experiment 2) and false recognition (Experiment 3) relative to unwarned participants. Importantly, the inability of explicit warnings to impact illusory recollections demonstrates that the false memories cannot be attributed simply to a criterion shift.     

Assessing the effectiveness of warnings and the phenomenological characteristics of false memories

The phenomenology of false memories was investigated in three experiments in which participants heard two experimenters read lists of items that were related to critical nonpresented items. In Experiments 1, following a recognition memory test, participants rated the phenomenological characteristics of their memories immediately and after a 48-hour delay. False recognition was prevalent and on several dimensions participants rated their true memories as more vivid than their false memories. In Experiments 2 and 3, following the study phase, participants were warned about the phenomenological differences between true and false memories and were instructed to use this information to avoid reporting nonpresented items. This type of warning was ineffective at reducing false recall (Experiment 2) and false recognition (Experiment 3) relative to unwarned participants. Importantly, the inability of explicit warnings to impact illusory recollections demonstrates that the false memories cannot be attributed simply to a criterion shift.     

Intended and unintended effects of explicit warnings on eyewitness suggestibility: Evidence from source identification tests

Previous studies have shown that source identification (ID) tests reduce, and in some cases eliminate, eyewitness suggestibility errors. The present study showed that the suggestibility errors participants committed on a source ID test were further reduced when they were given the explicit postwarning that the experimenter was trying to trick them. These postwarnings reduced suggestibility to the same extent as prewarnings, and they did so for both once and repeatedly suggested items. In addition, the benefits of the pre- and postwarnings persisted when participants were retested 1 week later, but only if the suggestions had been repeated. For once-suggested items, the warning had the unintended effect of improving old/new recognition of the suggested information at retest, an effect that offset the improvements in source discrimination accuracy conferred by the warning. The advantages of using source ID tests for investigating group differences in eyewitness suggestibility are discussed.     

‘Good,you identified the suspect…but please ignore this feedback’: can warnings eliminate the effects of post‐identification feedback?

The present experiments focus on whether the post‐identification feedback effect can be reduced by providing participants with warnings. Participants viewed a crime on video and identified a suspect from a target‐absent lineup (Experiment 1) or target‐present lineup (Experiment 2). Participants then received positive feedback, negative feedback or no feedback. Half of the participants received a warning saying their feedback was randomly generated by the computer, and the other half received no warning. Robust post‐identification feedback effects were observed in both experiments in the no warning condition. These effects were largely eliminated when participants received a warning. In Experiments 3 and 4, we failed to find an ameliorative effect of a forensically realistic warning. These results indicate that warnings can reduce the effect of post‐identification feedback in principle, but the application of warnings in practice may be more difficult. Copyright © 2006 John Wiley & Sons, Ltd.     

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.     

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.     

Listen Out! Behavioural and Subjective Responses to Verbal Warnings

Both the behavioural and subjective impacts of single‐word spoken warnings were examined. Behaviourally, the effect of infrequently occurring warnings was studied through their disruptive impact on a visually presented serial recall task. In separate experiments, ratings of the same words were elicited. Experiment 1 showed a localized effect of the warnings (on the item immediately following the warning), with the urgently intoned warning having a greater disruptive effect than its valence (emotional content). Valence and intonation (urgency) did not interact. The performance changes were mirrored in the ratings of the words. Experiment 2 showed no systematic effect on performance of either the action‐relatedness of the word or its lexicality. There was, however, a systematic effect of lexicality but not action‐relatedness on ratings. The study demonstrates the feasibility of using objective performance methods to establish the likely effects of verbal warnings and the utility of using such methods for the design of alarm systems. Copyright © 2012 John Wiley & Sons, Ltd.     

Associative false recognition occurs without strategic criterion shifts

In the DRM (Deese/Roediger and McDermott) false memory paradigm, subjects studied lists of words associated with nonpresented critical words. They were tested in one of four instructional conditions. In a standard condition, subjects were not warned about the DRM Effect. In three other conditions, they were told to avoid false recognition of critical words. One group was warned before study of the lists (affecting encoding and retrieval processes), and two groups were warned after study (affecting only retrieval processes). Replicating prior work, the warning before study considerably reduced false recognition. The warning after study also reduced false recognition, but only when critical items had never been studied; when critical items were studied in half the lists so that subjects had to monitor memory for their presence or absence, the warning after study had little effect on false recognition. Because warned subjects were trying to avoid false recognition, the high levels of false recognition in the latter condition cannot be due to strategically guessing that critical test items were studied. False memories in the DRM paradigm are not caused by such liberal criterion shifts.     

The effect of warnings on false memories in young and older adults

In the present experiments, we examined adult age differences in the ability to suppress false memories, using the Deese-Roediger-McDermott (DRM) paradigm (Deese, 1959; Roediger & McDermott, 1995). Participants studied lists of words (e.g., bed, rest, awake, etc.), each related to a nonpresented critical lure word (e.g., sleep). Typically, recognition tests reveal false alarms to critical lures at rates comparable to those for hits for studied words. In two experiments, separate groups of young and older adults were unwarned about the false memory effect, warned before studying the lists, or warned after study and before test. Lists were presented at either a slow rate (4 sec/word) or a faster rate (2 sec/word). Young adults were better able to discriminate between studied words and critical lures when warned about the DRM effect either before study or after study but before retrieval, and their performance improved with a slower presentation rate. Older adults were able to discriminate between studied words and critical lures when given warnings before study, but not when given warnings after study but before retrieval. Performance on a working memory capacity measure predicted false recognition following study and retrieval warnings. The results suggest that effective use of warnings to reduce false memories is contingent on the quality and type of encoded information, as well as on whether that information is accessed at retrieval. Furthermore, discriminating between similar sources of activation is dependent on working memory capacity, which declines with advancing age.     

Using warnings to reduce categorical false memories in younger and older adults

Warnings about memory errors can reduce their incidence, although past work has largely focused on associative memory errors. The current study sought to explore whether warnings could be tailored to specifically reduce false recall of categorical information in both younger and older populations. Before encoding word pairs designed to induce categorical false memories, half of the younger and older participants were warned to avoid committing these types of memory errors. Older adults who received a warning committed fewer categorical memory errors, as well as other types of semantic memory errors, than those who did not receive a warning. In contrast, young adults' memory errors did not differ for the warning versus no-warning groups. Our findings provide evidence for the effectiveness of warnings at reducing categorical memory errors in older adults, perhaps by supporting source monitoring, reduction in reliance on gist traces, or through effective metacognitive strategies.     

Forced fabrication versus interviewer suggestions: Differences in false memory depend on how memory is assessed

Many studies show that witnesses can develop false memories for suggested misinformation provided by an interviewer. The forced fabrication effect extends this finding by demonstrating that witnesses can also develop false memories for events they were forced to fabricate themselves. In two experiments we compared the incidence of false memory following forced fabrication and interviewer provided suggestion under various conditions (pre‐test warning/no warning; one‐week/two‐week delay) and type of test (source recognition vs. narrative recall). Whereas interviewer suggestions resulted in more false memories than forced fabrications on source recognition tests when participants overtly resisted fabricating and were warned at test, tests of narrative recall showed the opposite pattern even with pre‐test warnings: Fabrications generated following overt resistance led to more false recall than interviewer provided suggestions. This dissociation between suggestive interview type and test type indicates that predictions about the deleterious consequences of interviews are dependent on the way memory is assessed. Copyright © 2011 John Wiley & Sons, Ltd.     

Making it last: Combating hedonic adaptation in romantic relationships

Increasing evidence that positive affect enhances associative processing has lent weight to the idea that positive affect increases false memory for information that is thematically interrelated. Using the Deese–Roediger–McDermott paradigm, we examined whether mild positive affect facilitates monitoring processes in modulating false memory for associate words. When participants in the warned condition – in contrast to those in the unwarned condition – were overtly warned about possible false recognition of the critical lure, we found that positive affect, compared to neutral affect, significantly enhanced monitoring through a warning and reduced false recognition. Signal detection analyses suggest that when a warning is provided, positive affect enhances sensitivity to discriminate list items from critical lures, but it does not shift the overall decision criterion. Taken together, we conclude that positive affect facilitates the effect of a warning in reducing false memories for semantic associates.     

How do warnings influence cyclists' reaction to conflicts? Comparing acoustic and vibro-tactile warnings in different conflicts on a test track

An on-bike warning system has great potential to increase safety of cyclists. For an effective warning system, the implementation of warning signals is fundamental. However, more knowledge about the cyclist specific design of warnings and the influence of warnings on the cyclist is needed. To analyze the benefit of warnings in conflicts and the reaction pattern of cyclists we conducted a test-track experiment. We evaluated the data of 62 participants who were divided into three warning groups (between-subjects) and encountered different situations (within-subjects). The warning groups either received acoustic, vibro-tactile or no warnings. The situation variable consisted of three conflicts and two false warnings in the groups with warnings.We measured significantly shorter reaction times of persons who received acoustic and vibro-tactile warnings compared to the persons without warning. Furthermore, acoustic warnings led to shorter reaction times compared to vibro-tactile warnings. The reaction pattern was described by different bicycle dynamics variables. It was mostly influenced by the situation and rarely by the warning group. Based on the velocity curves and reaction times we identified learning effects describing how the warned participants adopted the warning system over the five situations.These findings indicate that a warning system offers great safety benefits to cyclists. Based on the current results, acoustic warnings are recommended when an urgent reaction is required.     

Paradoxical Effects of Warning in the Production of Children's False Memories

The effects of warning on false recognition and associated subjective experience of false recollection and familiarity were investigated in 7- to 13-year-old children and young adults (N = 259) using the Deese-Roediger-McDermott (DRM) paradigm. Two warning conditions (warning with an example of a critical lure and warning without an example of a critical lure) were compared to a control condition, in which no warning was received. We found that 7- to 8-year-olds exhibited higher false recognition in the warning-with-example condition compared with the control condition; in contrast, 12- to 13-year-olds and young adults exhibited reduced false recognition in the warning-with-example condition. No effect of warning was observed in 10- to 11-year-olds. The subjective experience associated with false memories was similar across ages. In contrast, age-related increases in subjective recollection were found for true memories. The processes that enhance or suppress false memories during development are discussed.     

Attempting to avoid false memories in the Deese/Roediger—McDermott paradigm: Assessing the combined influence of practice and warnings in young and old adults

On each of five study-test trials, young and old adults attempted to memorize the same list of 60 words (e.g., bed, rest, awake), which were blocked according to their convergence on four corresponding associates. Half of the participants in each age group were given an explicit warning about the DRM paradigm prior to encoding and were asked to attempt to avoid recalling any associated but nonpresented words (e.g., sleep). Lists were presented auditorily at either a fast (1,250 msec/word) or a slow (2,500 msec/word) rate. Without a warning, the probability of veridical recall across trials increased for both age groups; however, the probability of false recall across trials decreased only for young adults. When a warning about false recall was provided, young adults virtually eliminated false recall by the second trial. Even though old adults also used warnings to reduce false recall on Trial 1, they were still unable to decrease false memories across the remaining four study-test trials. Old adults also reduced false recall more with slow than with fast presentation rates. Taken together, these findings suggest that old adults have a breakdown in spontaneous, self-initiated source monitoring as reflected by little change in false recall across study-test trials but a preserved ability to use experimenter-provided warnings or slow presentation rates to reduce false memories.     

Using auditory streaming to reduce disruption to serial memory by extraneous auditory warnings

Three experiments were conducted to examine the effects of extraneous speech warnings (i.e., low-priority warnings initiated during high-priority tasks) on cognitive performance and whether organizing the auditory warnings into streams can attenuate any disruption. Experiment 1 demonstrated that a variety of speech warnings can be separated into perceptually distinct streams by allocating them to discrete spatial locations. Experiment 2 showed that increasing the rate of presentation of the warnings to promote streaming decreased clarity ratings but increased perceived urgency ratings. Experiment 3 demonstrated that the disruption to serial memory for navigational information by extraneous speech warnings could be attenuated by streaming. Results are interpreted in light of previous research, and practical implications for auditory warning design are discussed.     

Does a Judicial Warning Improve Defendant‐Culprit Matching?

During a trial, jurors may be asked to compare the defendant with video of the culprit. Yet matching unfamiliar people in this manner can be difficult and error‐prone. Judges may warn jurors about the dangers of identification from video images, but the effect of warnings is unknown. Here we report two studies that assessed the effect of warning instructions on defendant‐culprit matching. In Experiment 1, college students read either control, warning, or illustrated warning instructions before deciding if a defendant seen in one video matched the culprit in another video. Experiment 2 compared control and warning instructions in a sample of Amazon Mechanical Turk workers. Matching accuracy in both experiments was poor, and warnings did not consistently improve performance or make participants more cautious. These results do not support the supposition that warning instructions help jurors compare the defendant to images of the culprit.Copyright © 2016 John Wiley & Sons, Ltd.     

The ironic effect of guessing: increased false memory for mediated lists in younger and older adults

Younger and older adults studied lists of words directly (e.g., creek, water) or indirectly (e.g., beaver, faucet) related to a nonpresented critical lure (CL; e.g., river). Indirect (i.e., mediated) lists presented items that were only related to CLs through nonpresented mediators (i.e., directly related items). Following study, participants completed a condition-specific task, math, a recall test with or without a warning about the CL, or tried to guess the CL. On a final recognition test, warnings (vs. math and recall without warning) decreased false recognition for direct lists, and guessing increased mediated false recognition (an ironic effect of guessing) in both age groups. The observed age-invariance of the ironic effect of guessing suggests that processes involved in mediated false memory are preserved in aging and confirms the effect is largely due to activation in semantic networks during encoding and to the strengthening of these networks during the interpolated tasks.     

Test-induced priming impairs source monitoring accuracy in the DRM procedure

Three experiments investigated the effects of test-induced priming (TIP) on false recognition in the Deese/Roediger-McDermott procedure (Deese, 1959; Roediger & McDermott, 1995). In Experiment 1, TIP significantly increased false recognition for participants who made old/new decisions at test but not for participants who made remember/know judgments or were given diagnostic information to help them avoid false recognition. In Experiment 2, a TIP effect was observed with old/new recognition but not when participants were required to remember whether study items were spoken by a male or a female speaker. In Experiment 3, false recognition increased when critical lures were preceded by 10 studied items but not when preceded by 5 studied and 5 unstudied items from the same list. These findings suggest that TIP increases false recognition by disrupting source monitoring processes.