The effects of repeatedly recalling a traumatic event on eyewitness memory and suggestibility

ABSTRACT

The aims of this study were to examine the effects of repeatedly recalling a traumatic event on recall performance and eyewitness suggestibility. We also investigated whether these effects were moderated by the type of details recalled and the completeness of retrieval. Participants watched a video depicting a fatal car accident and were randomly allocated to one of four conditions in which they: (1) repeatedly recalled the traumatic (central) details of the event only (trauma-focused); (2) repeatedly recalled the non-traumatic (peripheral) details of the event only (non-trauma focused); (3) repeatedly recalled the entire video (complete); or (4) did not recall the video at all (no-recall control). Results indicated that repeated complete recall was beneficial for memory retention of the entire traumatic event and that, in general, trauma-related (central) post-event information (PEI) was less likely to be reported than trauma-unrelated (peripheral) PEI. It was also found that repeated trauma-focused recall increased trauma-related confabulations. These results not only illustrate the value of repeated complete recall to best preserve the integrity of eyewitness memory, but, perhaps more critically, warn of the dangers of repeatedly questioning witnesses specifically about the central or traumatic details of an event.     

Enhancing the quantity and accuracy of eyewitness memory via initial memory testing

Previous studies have demonstrated the benefits of initial memory testing in terms of “inoculating” eyewitness memory against forgetting. The aim of the present study was to determine to what extent and under which conditions such testing may also enhance the accuracy of subsequent retrieval. Two aspects of interpolated testing were manipulated: the mode of interpolated testing (forced verbatim vs. free level) and its timing (immediate vs. delayed). After witnessing a target event, participants were questioned about event details either immediately or after a 48-h delay, and were either required to respond at the verbatim level or were given control over the grain size of their responses. Verbatim memory for event details was finally tested 72 h after the event under both standard forced-report conditions and free-report conditions. Immediate interpolated testing was found to improve both memory quantity and memory accuracy on the final test, whereas delayed interpolated testing improved only memory quantity (and to a lesser extent). Although the mode of interpolated testing affected performance on the initial test, it had no effect on either memory quantity or memory accuracy on the final test. Practical implications with regard to eyewitness questioning are discussed.     

Inhibitory control in memory: Evidence for negative priming in free recall

Cognitive control mechanisms-such as inhibition-decrease the likelihood that goal-directed activity is ceded to irrelevant events. Here, we use the action of auditory distraction to show how retrieval from episodic long-term memory is affected by competitor inhibition. Typically, a sequence of to-be-ignored spoken distracters drawn from the same semantic category as a list of visually presented to-be-recalled items impairs free recall performance. In line with competitor inhibition theory (Anderson, 2003), free recall was worse for items on a probe trial if they were a repeat of distracter items presented during the previous, prime, trial (Experiment 1). This effect was produced only when the distracters were dominant members of the same category as the to-be-recalled items on the prime. For prime trials in which distracters were low-dominant members of the to-be-remembered item category or were unrelated to that category-and hence not strong competitors for retrieval-positive priming was found (Experiments 2 and 3). These results are discussed in terms of inhibitory approaches to negative priming and memory retrieval. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

The dark side of testing memory: repeated retrieval can enhance eyewitness suggestibility

Eyewitnesses typically recount their experiences many times before trial. Such repeated retrieval can enhance memory retention of the witnessed event. However, recent studies (e.g., Chan, Thomas, & Bulevich, 2009) have found that initial retrieval can exacerbate eyewitness suggestibility to later misleading information--a finding termed retrieval-enhanced suggestibility (RES). Here we examined the influence of multiple retrieval attempts on eyewitness suggestibility to subsequent misinformation. In four experiments, we systematically varied the number of initial tests taken (between zero and six), the delay between initial testing and misinformation exposure (~30 min or 1 week), and whether initial testing was manipulated between- or within-subjects. University undergraduate students were used as participants. Overall, we found that eyewitness suggestibility increased as the number of initial tests increased, but this RES effect was qualified by the delay and by whether initial testing occurred in a within- or between-subjects manner. Specifically, the within-subjects RES effect was smaller than the between-subjects RES effect, possibly because of the influence of retrieval-induced forgetting/facilitation (Chan, 2009) when initial testing was manipulated within subjects. Moreover, consistent with the testing effect literature (Roediger & Karpicke, 2006), the benefits of repeated testing on later memory were stronger after a 1-week delay than after a 30-min delay, thus reducing the negative impact of RES in long-term situations. These findings suggest that conditions that are likely to occur in criminal investigations can either increase (repeated testing) or reduce (delay) the influence of RES, thus further demonstrating the complex relationship between eyewitness memory and repeated retrieval.     

Enhancing retention through reconsolidation: negative emotional arousal following retrieval enhances later recall

When information is retrieved from memory, it enters a labile state rendering it amenable to change. This process of reconsolidation may explain, in part, the benefits that are observed in later retention following retrieval of information on an initial test. We examined whether the benefits of retrieval could be modulated by an emotional event occurring after retrieval. Participants studied Swahili-English vocabulary pairs. On a subsequent cued-recall test, each retrieval was followed by a blank screen, a neutral picture, or a picture inducing negative affect. Performance on a final cued-recall test was best for items whose initial retrieval was followed by negative pictures. This outcome occurred when a negative picture was presented immediately after (Experiment 1) or 2 s after (Experiment 2) successful retrieval, but not when it was presented after restudy of the vocabulary pair (Experiment 3). Postretrieval reconsolidation via emotional processing may enhance the usual positive effects of retrieval.     

Effect of negative emotional content on working memory and long-term memory

In long-term memory, negative information is better remembered than neutral information. Differences in processes important to working memory may contribute to this emotional memory enhancement. To examine the effect that the emotional content of stimuli has on working memory performance, the authors asked participants to perform working memory tasks with negative and neutral stimuli. Task accuracy was unaffected by the emotional content of the stimuli. Reaction times also did not differ for negative relative to neutral words, but on an n-back task using faces, participants were slower to respond to fearful faces than to neutral faces. These results suggest that although emotional content does not have a robust effect on working memory, in some instances emotional salience can impede working memory performance.     

The effects of memory trace strength on eyewitness recall in children with and without intellectual disabilities

Children with mild moderate intellectual disabilities (ID) were compared with typically developing peers of the same chronological age (CA) on an eyewitness memory task in which memory trace strength was manipulated to examine whether increased memory trace strength would benefit those with ID more than those without ID. No evidence was found for this claim or for the notion that different mechanisms are implicated in memory processes for children with ID versus CA controls. Fuzzy-trace theory was also used to contrast question types that probed verbatim memory versus gist memory. Manipulations of trace strength, when used with immediate recall (to reduce the impact of decay), were predicted to improve verbatim memory more than gist memory. The results broadly supported the predictions. Performance was not improved in the stronger trace strength condition on measures of recall that tapped gist memory (e.g., open-ended recall), whereas performance was significantly better in the stronger trace strength condition on two of the three measures of recall that tapped verbatim memory (i.e., closed misleading questions, open-ended specific questions). Differences in performance between the groups were quite marked on several question types, supporting previous findings that those with ID have certain vulnerabilities as potential witnesses compared with peers of the same CA.     

Failure of positive but not negative emotional valence to enhance memory in schizophrenia

Abnormalities in the integration of emotion and cognition have long been considered hallmark characteristics of schizophrenia. Study authors used a well-established emotional memory model from the neuroscience literature to assess the facilitative impact of emotional valence of information on long-term memory consolidation in schizophrenia. Participants with schizophrenia (n=33) indicated somewhat higher levels of emotional intensity in response to emotional images than did healthy (n=28) participants. However, when recognition memory was tested 24 hr later, schizophrenia participants did not show enhancement of memory for positive images as was found in healthy participants. Their memory enhancement for negative images did not differ from that of healthy participants. Correlations between self-reported physical and social anhedonia were significantly inversely correlated with intensity ratings of positive stimuli during the encoding phase for healthy participants but were negligible for schizophrenia participants. These results suggest a failure to adequately integrate positive emotional experience in memory consolidation processes in schizophrenia participants, despite appropriate initial response to positive stimuli, which may contribute to symptoms such as anhedonia by reducing the long-term impact of positive experiences in motivating hedonic behavior in day-to-day life.     

Emotional stress and eyewitness memory: a critical review.

The eyewitness literature often claims that emotional stress leads to an impairment in memory and, hence, that details of unpleasant emotional events are remembered less accurately than details of neutral or everyday events. A common assumption behind this view is that a decrease in available processing capacity occurs at states of high emotional arousal, which, therefore, leads to less efficient memory processing. The research reviewed here shows that this belief is overly simplistic. Current studies demonstrate striking interactions between type of event, type of detail information, time of test, and type of retrieval information. This article also reviews the literature on memory for stressful events with respect to two major theories: the Yerkes-Dodson law and Easter-brook's cue-utilization hypothesis. To account for the findings from real-life studies and laboratory studies, this article discusses the possibility that emotional events receive some preferential processing mediated by factors related to early perceptual processing and late conceptual processing.     

Dream recall frequency and openness to experience: a negative finding

The question of whether personality dimensions explain the interindividual differences in dream recall frequency has often been investigated by dream researchers. Previous research has shown that traits such as absorption, hypnotic susceptibility and thin boundaries which are related to the openness-to-experience factor of the Five-Factor-Model of personality correlate substantially with dream recall frequency. The present study, however, was unable to demonstrate a relationship between openness and the six facet scales and dream recall frequency. It may be hypothesized that other factors such as visual memory, sleep behavior or creativity explain the interindividual differences in dream recall.     

Role of environmental context in eyewitness memory

We investigated whether varying the environmental context will affect the magnitude of retroactive interference produced by misleading postevent information in an eyewitness memory paradigm. Previous eyewitness memory studies have typically presented the original and misleading information in the same environmental context. In this experiment, the physical contexts in which the original information and the misleading information were presented were varied, a procedure that is more analogous to what usually occurs in real world situations. We tested 288 subjects, half using the original and misleading information in the same encoding context and half using a different context for presenting the two types of information. Memory for the original event was assessed using either the standard recognition test procedure or the modified test developed by McCloskey and Zaragoza (1985). Measures of both recognition accuracy and response latency showed no difference in performance attributable to varying the environmental context. The present data replicate the findings of previous single-context experiments that showed the two recognition test procedures to produce different patterns of results. Thus, environmental context seems to play little role in determining the magnitude of the misleading postevent information effect.     

Misleading postevent information and working memory capacity: an individual differences approach to eyewitness memory

The present study examines how individual differences in working memory capacity relate to the effect of misleading postevent information on memory for the original event. Participants were shown a film of a crime event and were then asked to unscramble a narrative that included misinformation regarding some of the film's details. Additionally, the working memory capacity of the participants was measured using the operation‐word span task. Finally, in a free recall test, participants recalled fewer correct details in the misinformation condition compared to the control condition. This effect was negatively correlated with working memory capacity. Copyright © 2002 John Wiley & Sons, Ltd.     

Paradoxical effects of testing: Repeated retrieval attempts enhance the likelihood of later accurate and false recall

The testing effect is the finding that taking an initial test enhances the likelihood of later recall. The present report examines the extent to which this benefit of testing comes with a cost: an enhanced likelihood of erroneously recalling incorrect information. Subjects were given short lists of semantic associates (e.g., hill, valley, climb); each list converged upon a related nonpresented word (e.g., mountain). After presentation of some lists, the subjects received no initial test; after others, one initial free recall test; and after others, three successive free recall tests. The probabilities of final free recall (and the probability of reporting vivid recollection of the moment of encoding) of both studied and related, nonstudied words (e.g., mountain) were highest when three initial tests had been taken, intermediate following one initial test, and lowest when no initial test had occurred. The beneficial effects of testing carry the cost of increases in erroneous memory for related information.     

Resisting emotional interference: Brain regions facilitating working memory performance during negative distraction

Survival-relevant information has privileged access to our awareness even during active cognitive engagement. Previous work has demonstrated that during working memory (WM) negative emotional distraction disrupts activation in the lateral prefrontal regions while also engaging the amygdala. Here, using slow eventrelated fMRI, we replicate and extend previous work examining the effect of negative emotional distraction on WM: (1) We demonstrate that prefrontal regions showed activation differences between correct and incorrect trials during negative, but not neutral, distraction. Specifically, frontopolar prefrontal cortex showed more deactivation for incorrect trials faced with negative distraction, whereas ventrolateral prefrontal regions showed less activation; (2) individual differences in amygdala activity predicted WM performance during negative as well as neutral distraction, such that lower activity predicted better performance; and (3) amygdala showed negative correlations with prefrontal and parietal cortical regions during resting state. However, during negative distraction, amygdala signals were more negatively correlated with prefrontal cortical regions than was found for resting state and neutral distraction. These results provide further evidence for an inverse relationship between dorsal prefrontal cortical regions and the amygdala when processing aversive stimuli competes with ongoing cognitive operations, and further support the importance of the prefrontal cortex in resisting emotional interference. Supplemental materials associated with this article may be downloaded from http://cabn.psychonomic-journals .org/content/supplemental.     

Mood effects on eyewitness memory: Affective influences on susceptibility to misinformation

Does mood influence the accuracy of eyewitness recollections, and people’s susceptibility to misleading information in particular? Based on recent affect-cognition theories and research on eyewitness memory, three experiments predicted and found that positive affect promoted, and negative affect inhibited the incorporation of misleading information into eyewitness memories. This effect was obtained for both positive and negative events (Experiment 1), and for recorded as well as real-life incidents (Experiment 2). Participants had no meta-cognitive awareness of these mood effects, and affect-control instructions were ineffective in preventing them (Experiment 3). The cognitive mechanisms responsible for mood effects on eyewitness memories are discussed, and the implications of these findings for everyday memories, forensic practice and for current affect/cognition theorizing are considered.     

Effect of negative emotional pictures on associative memory for peripheral information

We investigated the influence of negative emotional pictures on associative memory. A visual object was embedded in the periphery of negative emotional or neutral pictures. Memory was assessed for central item (pictorial) information, peripheral (object) information, and the association between item and peripheral information. On tests of item information, negative emotional pictures were remembered better than neutral pictures. However, associative memory between item and peripheral information was less accurate when the pictures were negative compared to neutral. This occurred despite equivalent recall (Experiments 1 and 2) and recognition (Experiment 2) for the peripheral objects themselves. Further experiments confirmed that performance on the associative test was not influenced by testing order (Experiment 3). These findings suggest that negative emotional arousal can particularly disrupt the associative binding of peripheral information to a central emotional event.     

Episodic remembering creates access to involuntary conscious memory: demonstrating involuntary recall on a voluntary recall task

The idea that involuntary memory retrieval might occur during voluntary memory retrieval can be traced back to Ebbinghaus (1885/1964). However, methodological challenges have stood in the way of testing this idea. Recent diary studies of naturally occurring involuntary memories have provided insights into how this idea could be tested (Berntsen, 1998; Mace, 2005b, 2006). These studies have shown that the contents of an involuntary memory sometimes trigger additional involuntary memories, a process called chaining. It was hypothesised that chaining should also occur on autobiographical memory tasks, and this was tested in the present study by asking participants in an autobiographical memory task to report the presence of involuntary memories while they were performing the task. The results showed that involuntary memories did occur when participants were recalling the past. The results also showed involuntary memories dissociating from voluntary memories on two independent measures, thereby enhancing the credibility of the results.