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.     

Fuzzy-trace theory and memory development

We review recent applications of fuzzy-trace theory to memory development, organizing the presentation around two themes: the theory’s explanatory principles and experimental findings about memory development that follow as predictions from those principles. The featured explanatory principles are: parallel storage of verbatim and gist traces, dissociated retrieval of verbatim and gist traces, differential survival rates for verbatim and gist traces, retrieval phenomenology, and developmental trends in verbatim and gist memory. The experimental findings come from four different areas of research: the development of retrieval phenomenologies, “reversed” developmental trends in false memory, the development of mere testing effects, and the development of false persistence in memory.     

The basic-level convergence effect in memory distortions

Abstract— Whereas most previous findings suggest that memory may become more abstract over time, so that memory for gist outlasts verbatim memory, there are findings suggesting that abstract information may sometimes be instantiated in more specific terms. In this study, we examined the hypothesis that retained information tends to converge at an intermediate level of abstractness—the basic level. In two experiments, we found bidirectional, symmetrical shifts in the memory for story material: Participants presented with either subordinate terms (e.g., sports car) or superordinate terms (e.g., vehicle) tended to falsely report basic-level terms (e.g., car) instead. This pattern emerged for both recall and recognition memory tests, at both immediate and delayed testing, and under free and forced reporting. The results suggest that the basic level, which has been considered cognitively optimal for perception, categorization, and communication, is also the preferred level for retaining episodic information in memory.     

The role of self-esteem in the misinformation effect

Previous research using the Gudjonnson suggestibility scale has suggested a role for self-esteem in suggestibility, with participants low in self-esteem being more suggestible than participants high in self-esteem. Four experiments are presented examining the role of self-esteem in the misinformation effect and whether enhanced suggestibility effects in participants low in self-esteem reflect genuine memory impairment. In Experiments 1 and 4 participants completed a standard recognition test. In Experiment 2 participants completed the modified recognition test. In Experiment 3 participants completed a free recall test. In Experiments 1 and 4 participants low in self-esteem demonstrated greater misinformation effects than participants high in self-esteem. In Experiment 3 a 3-day retention interval was employed with the modified test and no differences were found between the two groups on the reporting of the new item. The findings suggest that participants low in self-esteem are particularly sensitive to demand characteristics and post-event suggestion but do not suffer from genuine memory impairment.     

The role of self-esteem in the misinformation effect

Previous research using the Gudjonnson suggestibility scale has suggested a role for self-esteem in suggestibility, with participants low in self-esteem being more suggestible than participants high in self-esteem. Four experiments are presented examining the role of self-esteem in the misinformation effect and whether enhanced suggestibility effects in participants low in self-esteem reflect genuine memory impairment. In Experiments 1 and 4 participants completed a standard recognition test. In Experiment 2 participants completed the modified recognition test. In Experiment 3 participants completed a free recall test. In Experiments 1 and 4 participants low in self-esteem demonstrated greater misinformation effects than participants high in self-esteem. In Experiment 3 a 3-day retention interval was employed with the modified test and no differences were found between the two groups on the reporting of the new item. The findings suggest that participants low in self-esteem are particularly sensitive to demand characteristics and post-event suggestion but do not suffer from genuine memory impairment.     

Fallacies in memory for conversations: Reflections on Clarence Thomas,Anita Hill,and the Like

This study examines conditions that relate to fallacies in memory for conversations. This research tests a cognitive interpretation for why a conversation might be vividly memorable to one eyewitness but not to another. Specifically, a test of gist and verbatim memory for sexual versus non sexual material is presented. In addition, the relative memorability of sexual versus non sexual mateial is tested as a function of the consistency of the context in which it is presented. In two experiments participants heard a recorded conversation between a man and a woman that included four sexual and four non sexual target sentences. The conversation was framed as having been recorded in either a singles bar (the consistent context) or an office setting (the inconsistent context). Sexual items were recalled and recognized better than non sexual items, on both gist and verbatim memory tasks, and the difference in gist (but not verbatim) memory between sexual and non sexual items was greater in the inconsistent than in the consistent context. The discussion considers how this pattern of results might illuminate slippages in memory that may have occured during the Clarence Thomas-Anita Hill hearing (U. S. Supreme Court appointment review; October 1991) as well as memory slippages more generally.     

How events are reviewed matters: effects of varied focus on eyewitness suggestibility

Witnesses to a crime or an accident perceive that event only once, but they are likely to think or talk about it multiple times. The way in which they review the event may affect their later memory. In particular, some types of review may increase suggestibility if the witness has been exposed to postevent misleading information. In Experiment 1, participants viewed a videotaped crime and then received false suggestions about the event. We found that participants who were then asked to focus on specific details when reviewing the event were more suggestible on a later source memory test than participants asked to review the main points. The findings of Experiment 2 suggest that this effect was not due to a criterion shift at test. These findings indicate that the type of rehearsal engaged in after witnessing an event can have important consequences for memory and, in particular, suggestibility.     

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.     

Repeated testing in eyewitness memory: a means to improve recall of a negative emotional event

Participants viewed either a violent, arousing film or a non-violent, control version of the same film. After viewing the film, they made three successive attempts to recall details of the event. Participants who were exposed to the negative emotional event were better than control participants at recalling details of the event itself, but they were worse at recalling details that preceded or followed the violence. Both groups of participants recalled significantly more information over successive recall attempts, suggesting that memory impairment due to arousal can be alleviated by repeated testing. Repeated testing was also associated with a small but reliable increase in memory intrusions. The implications of these findings for research on hypermnesia and on the relationship between arousal and memory are discussed. © 1998 John Wiley & Sons, Ltd.     

Developmental reversals in false memory: now you see them, now you don't!

A developmental reversal in false memory is the counterintuitive phenomenon of higher levels of false memory in older children, adolescents, and adults than in younger children. The ability of verbatim memory to suppress this age trend in false memory was evaluated using the Deese-Roediger-McDermott (DRM) paradigm. Seven and 11-year-old children studied DRM lists either in a standard condition (whole words) that normally produces high levels of false memory or in an alternative condition that should enhance verbatim memory (word fragments). Half the children took 1 recognition test, and the other half took 3 recognition tests. In the single-test condition, the typical age difference in false memory was found for the word condition (higher false memory for 11-year-olds than for 7-year-olds), but in the word fragment condition false memory was lower in the older children. In the word condition, false memory increased over successive recognition tests. Our findings are consistent with 2 principles of fuzzy-trace theory's explanation of false memories: (a) reliance on verbatim rather than gist memory causes such errors to decline with age, and (b) repeated testing increases reliance on gist memory in older children and adults who spontaneously connect meaning across events.     

The impact of experienced versus non‐experienced suggestions on children's recall of repeated events

Three experiments were conducted to test the proposition that children's suggestibility about an occurrence of a repeated event is heightened when an interviewer suggests false details that were experienced in non‐target occurrences of the event as opposed to new details that never occurred. In each experiment, children participated in a repeated event during which specific items varied each time (e.g. the children always got a sticker but the theme of the sticker was different in each occurrence). Separate biasing and memory interviews were then conducted. In Experiment 1, the interviewer merely suggested that the false details might have occurred in the event. In the remaining experiments, the suggested details were clearly linked to the target occurrence with either a contextual or temporal cue. The potential moderating effect of the child's age (Experiment 1) and the retention interval (Experiments 1 and 2) were also examined. Consistent with the initial hypothesis, suggestions about experienced (non‐target) details were more likely to be repeated by the children compared to suggestions about non‐experienced details. In Experiments 2 and 3, experienced suggestions were also more likely to inhibit children's recall of the target occurrence. The relevance and generalizability of these findings to the legal setting are discussed. Copyright © 2006 John Wiley & Sons, Ltd.     

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.     

Suggestibility effects persist after one year in children who experienced a single or repeated event

The study of long-term memory for repeated events has important implications for understanding autobiographical memory in a forensic context. Recall accuracy and suggestibility for details of an instance of a repeated event versus a single event were examined in children aged 5–6 and 7–8 years after a one-year delay. Children who reported an instance of a repeated event were more likely to report that a non-experienced detail had occurred and reported less correct information than did single-event children. After one year a significant suggestibility effect was still present. The present experiment provides further evidence for both the capabilities and limitations of children's long-term recall and reinforces the importance of non-suggestive interviews of children at all stages of investigation.     

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.     

Event frequency and children's suggestibility: a study of cued recall responses

Research examining the effect of repeated experience on children's suggestibility for particular kinds of information has produced differing results. In one study, responses to recognition questions revealed heightened suggestibility for variable details in children who repeatedly experienced an event compared to children who experienced an event once. In other studies, no such effect was found with cued recall. In this study, 4–5‐year old children engaged in one or four play sessions. Children were later given a biasing interview wherein half of the details were incorrectly represented. Children were then given a final memory test using free and cued recall prompts that was preceded by one of three instruction types: no special instructions, moderate instructions, or opposition instructions. Children in the repeated‐event condition were more suggestible than those in the single‐event condition, regardless of instructions. No significant differences in suggestibility were found across instructions conditions. Copyright © 2004 John Wiley & Sons, Ltd.     

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.     

How fuzzy-trace theory predicts true and false memories for words,sentences, and narratives

Fuzzy-trace theory posits independent verbatim and gist memory processes, a distinction that has implications for such applied topics as eyewitness testimony. This distinction between precise, literal verbatim memory and meaning-based, intuitive gist accounts for memory paradoxes including dissociations between true and false memory, false memories outlasting true memories, and developmental increases in false memory. We provide an overview of fuzzy-trace theory, and, using mathematical modeling, also present results demonstrating verbatim and gist memory in true and false recognition of narrative sentences and inferences. Results supported fuzzy-trace theory's dual-process view of memory: verbatim memory was relied on to reject meaning-consistent, but unpresented, sentences (via recollection rejection). However, verbatim memory was often not retrieved, and gist memory supported acceptance of these sentences (via similarity judgment and phantom recollection). Thus, mathematical models of words can be extended to explain memory for complex stimuli, such as narratives, the kind of memory interrogated in law.     

Gist-based memory for prices and “better buys” in younger and older adults

Ageing typically leads to various memory deficits which results in older adults’ tendency to remember more general information and rely on gist memory. The current study examined if younger and older adults could remember which of two comparable grocery items (e.g., two similar but different jams) was paired with a lower price (the “better buy”). Participants studied lists of grocery items and their prices, in which the two items in each category were presented consecutively (Experiment 1), or separated by intervening items (Experiment 2). At test, participants were asked to identify the “better buy” and recall the price of both items. There were negligible age-related differences for the “better buy” in Experiment 1, but age-related differences were present in Experiment 2 when there were greater memory demands involved in comparing the two items. Together, these findings suggest that when price information of two items can be evaluated and compared within a short period of time, older adults can form stable gist-based memory for prices, but that this is impaired with longer delays. We relate the findings to age-related changes in the use of gist and verbatim memory when remembering prices, as well as the associative deficit account of cognitive ageing.     

Effects of perceptual modality on verbatim and gist memory

In two experiments, predictions of the fuzzy-trace theory of memory were tested. Perceptual information may play a role in retrieval and recognition processes for verbatim, but not for gist, memory. Perceptual modality effects were assessed in the present study by presenting three-sentence stories (e.g.,The bird is in the cage. The cage is over the table. The bird is yellow) and then testing recognition of probes that varied on three dimensions: (1) semantic accuracy (true vs. false), (2) wording (all original words vs. one novel word included), and (3) sentence type (premise vs. inference). In Experiment 1, study modality (auditory vs. visual) was manipulated, and in Experiment 2, both study and test modalities were manipulated. Despite replicating a number of findings consistent with fuzzy-trace theory (e.g., instruction and probe type effects), the results of both experiments failed to support the idea that perceptual information plays a role in performance on verbatim memory tests.     

Misleading Suggestions can Alter Later Memory Reports even Following a Cognitive Interview

Taking an immediate recall test prior to misinformation exposure can increase eyewitness suggestibility—a finding termed retrieval‐enhanced suggestibility. Here, we examined whether retrieval‐enhanced suggestibility would occur when participants were administered an immediate Cognitive Interview (CI). The CI is an investigative interviewing technique that consistently elicits more correct details in memory reports than standard interviews. In this study, participants watched a video of a crime and then completed a distractor task (control condition), a free recall test, or the CI. They then heard misinformation presented in a narrative. Participants produced more accurate memory details in the CI than in free recall despite spending equal time on both tasks. However, the CI also increased the later report of misinformation relative to the control condition. These results show that initial retrieval can increase subsequent suggestibility even when such retrieval occurs under relatively ideal conditions. Copyright © 2013 John Wiley & Sons, Ltd.