Misled subjects may know more than their performance implies

Many studies have demonstrated that subjects exposed to misleading postevent information are likely to report the misinformation with confidence on subsequent tests of memory for the event. The purpose of the present studies was to determine whether subjects exposed to misleading postevent information come to believe they remember seeing the misinformation at the original event. A second question addressed by the present studies is whether exposure to misinformation reduces subjects' ability to remember the source of items they witnessed at the original event. In two experiments, subjects viewed a slide sequence depicting an event, were subsequently exposed to misleading information or neutral information about selected aspects of the event, and were later tested on their memory for the source of original and misleading details. The results showed that exposure to misinformation did not lead subjects to believe they remembered seeing the misinformation, nor did it reduce subjects' ability to accurately identify the source of originally seen details. The same pattern of results was obtained whether subjects were tested immediately (Experiment 1) or after a 1-day delay (Experiment 2). Collectively, the results suggest that subjects may report misinformation even if they know they do not remember seeing it.     

Memory strength affects reporting of misinformation

A model of long-term retention was used to examine whether and how the strength of original information (differences in learning and testing time) and the strength of misleading information (differences in timing and frequency) influence 3- to 5-year-olds' memory for an event. In three experiments, preschoolers viewed a slide presentation depicting an event, some of them were asked misleading questions, and memory for event details was tested. There was little evidence of memory impairment, but exposure to misleading information encouraged reporting of this information. Differences in learning influenced reporting in that children exposed to the event once reported more misled details than those who saw the event multiple times. Furthermore, preschoolers who saw the event once were just as susceptible to misleading information whether exposed to misinformation once or three times; however, preschoolers who had seen the event multiple times were susceptible only to repeated presentations of misinformation. Given that the reporting of misinformation is determined by the degree of integrity of both the original and misleading information, it is important to control for differences in trace strength for both types of information in future research.     

The quality of false memory over time: Is memory for misinformation “remembered” or “known”?

The conscious quality of eyewitness memory for misinformation after different retention intervals was investigated in two experiments. Participants viewed computer-projected slides depicting a crime (encoding phase), read a narrative containing misinformation, and took a recall test about the original event. Remember/know judgments were made for each response. A "remember" judgment indicated that the participant vividly recalled seeing a detail in the encoding phase. A "know" judgment indicated that the participant believed that a detail was presented but did not vividly remember it. Generally, misinformation was more likely to be associated with a know judgment than with a remember judgment after a short retention interval. This outcome suggests that, in many cases, misleading information is judged as having a different subjective quality than memory for actual events. However, over a relatively long retention interval, misinformation that simply added new information about the event was more often judged as remembered.     

Memory impairment in the weapon focus effect

Two experiments are reported in which postevent source of misinformation was manipulated within weaponpresent and weapon-absent scenarios. Participants viewed slides depicting either a weapon or a newspaper event and then received either incomplete questioning or a narrative. Both postevent sources contained misleading information about a central and peripheral detail concerning either the weapon or the newspaper scenario. With a modified test in Experiment 1, questioning was found to increase misinformation effects concerning the central item, as compared with a narrative, and more misinformation effects were found for the weapon-peripheral than for the newspaper-peripheral item. In Experiment 2, the participants were more likely to claim to have seen contradictory and additive misinformation about the central item in the slides following questioning, and more contradictory and additive misinformation effects occurred for the weapon-peripheral than for the newspaper-peripheral item. The findings are considered in terms of the effects of both postevent and encoding factors on memory.     

Overcoming Misinformation Effects in Eyewitness Memory: Effects of Encoding Time and Event Cues

Eyewitness memory is often distorted when misleading information is presented to subjects after encoding. Three experiments explored ways to overcome these misinformation effects. In Experiment 1, subjects viewed slides of a robbery, at a rate of four or seven seconds per slide. Five minutes later subjects were given a recognition test with few (1–3) or numerous (6–13) event cues. Providing numerous retrieval cues improved overall performance, but did not reduce the effects of misinformation. W ith week-long delays (Experiment 2) numerous retrieval cues did eliminate misinformation effects, but only when subjects viewed slides at the slower rate (seven seconds per slide). Experiment 3 essentially replicated this pattern, using a modified test to eliminate any biasing effects of distractors. Given adequate encoding and numerous retrieval cues, misinformation effects were eliminated, suggesting that under some conditions misinformation makes event memory inaccessible, but not unavailable.     

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.     

Adult Age‐Related Differences in the Misinformation Effect for Context‐Consistent and Context‐Inconsistent Objects

The present study examined age‐related differences in the misinformation effect for objects that were consistent or inconsistent with their environmental settings. Young and older adults viewed one of two slide sequences, each containing context‐consistent items (e.g., a blender in a kitchen setting or a saw in a woodshop setting) and context‐inconsistent items (a saw in a kitchen setting or a blender in a woodshop setting). After receiving misinformation through post‐event narratives, participants received tests of yes/no recognition requiring remember/know judgments (Experiments 1–3) and source monitoring (Experiments 2 and 3) for slide details. Although age‐related differences in the misinformation effect were nonreliable, older adults tended to report misinformation as remembered more often than young adults, and source monitoring tests reduced the misinformation effect for both age groups. Misinformation effects were equivalent or larger for inconsistent objects than for consistent objects. Theoretical and practical implications of these results are discussed. Copyright © 2013 John Wiley & Sons, Ltd.     

Trauma and memory: effects of post-event misinformation, retrieval order, and retention interval

The present study concerned effects of misinformation, retrieval order, and retention interval on eyewitness memory for a traumatic event (a vivid murder). Relations between misinformation acceptance and compliance were also examined. The classic three-stage misinformation paradigm (Loftus, 1979) was employed, with a multi-component recognition test added. Either immediately or 2 weeks after viewing a distressing film, 232 adults read a narrative (misleading or control) about the murder and then took a recognition test that tapped memory for central and peripheral details. Test-item order either matched the chronology of the film or was randomly determined. Significant misinformation effects were obtained. Moreover, control participants were more accurate in response to questions about central than peripheral information; however, this was not so for misinformed participants. Sequential but not random retrieval order resulted in a higher proportion of correct responses for central as opposed to peripheral misinformation questions. Compliance was significantly related to misinformation effects. Delay increased participants' suggestibility, impaired memory accuracy, and produced higher confidence ratings for misinformed participants compared to controls. Findings indicate that even for a highly negative event, adults' memory is not immune to inaccuracies and suggestive influences.     

Is saccade-induced retrieval enhancement a potential means of improving eyewitness evidence?

Saccade-induced retrieval enhancement (SIRE) is the effect whereby making bilateral saccades enhances the subsequent retrieval of memories. Two experiments explored SIRE's potential to improve eyewitness evidence. Participants viewed slideshows depicting crimes, and received contradictory and additive misinformation about event details either once (Experiment 1) or three times (Experiment 2). Participants then performed saccades or a fixation control task before being tested on their memory for the slideshows and making confidence judgements. Saccades increased discrimination between seen and unseen event details regardless of whether or what type of misinformation was presented. Because prior studies indicated that SIRE might be more robust for individuals who are strongly right-handed versus not, we examined SIRE as a function of handedness and found that saccades improved memory for event details regardless of participants' handedness. However, participants who were not strongly right-handed had fewer false memories than participants who were strongly right-handed, extending previous findings of superior memory among individuals who are not strongly right-handed. Saccades also increased confidence in true memories (Experiment 1) and decreased confidence in false memories (Experiment 2). The results support SIRE's potential to improve eyewitness evidence.     

Age-related changes in the misinformation effect

In these experiments, we examined the relation between age-related changes in retention and age-related changes in the misinformation effect. Children (5- and 6- and 11- and 12-year-olds) and adults viewed a video, and their memory was assessed immediately, 1 day, or 6 weeks later (Experiment 1). There were large age-related differences in retention when participants were interviewed immediately and after 1 day, but after the 6-week delay, age-related differences in retention were minimal. In Experiment 2, 11- and 12-year-olds and adults were exposed to neutral, leading, and misleading postevent information 1 day or 6 weeks after they viewed the video. Exposure to misleading information increased the number of commission errors, particularly when participants were asked about peripheral aspects of the video. At both retention intervals, children were more likely than adults to incorporate the misleading postevent information into their subsequent verbal accounts. These findings indicate that age-related changes in the misinformation effect are not predicted by age-related changes in retention.     

Dividing attention during a witnessed event increases eyewitness suggestibility

Real‐life witnesses often encounter complex situations that may prevent them from devoting their full attention to encoding forensically‐relevant information about the event. Although prior research has demonstrated that divided attention can impair aspects of event memory, the current study examined the effect of attention during encoding of the event on participants' memory for the source of post‐event misleading information. Participants first viewed a slide sequence depicting a theft under full or divided attention conditions. Subsequently, they answered questions about the event that included misleading information, and finally received a source test. Results revealed that Divided Attention participants showed poorer memory for event items and were more likely to misattribute post‐event misinformation to the event than were Full Attention participants. The findings suggest that typical laboratory conditions (which allow full deployment of attentional resources during encoding) may underestimate the suggestibility of witnesses. Copyright © 2006 John Wiley & Sons, Ltd.     

Source monitoring and suggestibility to misinformation: adult age‐related differences

We compared young and older adults' source monitoring performance on an explicit source identification test using the misinformation paradigm. Several age‐related differences in source memory were demonstrated: (a) older adults were more likely than were young adults to say that they saw information that was actually only suggested to them; (b) older adults were more confident in their false memories than were young adults; (c) older adults were less confident in their accurate memory for the source of information than were young adults. Together, the data suggest that older adults either lacked or failed to use helpful diagnostic source information (e.g. perceptual details or temporal information), and that their confidence in their false memories reflected an over‐weighting of semantic information. Copyright © 2002 John Wiley & Sons, Ltd.     

Why misinformation is reported: evidence from a warning and a source-monitoring task

People report suggested misinformation about a previously witnessed event for manifold reasons, such as social pressure, lack of memory of the original aspect, or a firm belief to remember the misinformation from the witnessed event. In our experiments (N?=?429), which follow Loftus's paradigm, we tried to disentangle the reasons for reporting a central and a peripheral piece of misinformation in a recognition task by examining (a) the impact a warning about possible misinformation has on the error rate, and (b) whether once reported misinformation was actually attributed to the witnessed event in a later source-monitoring (SM) task. Overall, a misinformation effect was found for both items. The warning strongly reduced the misinformation effect, but only for the central item. In contrast, reports of the peripheral misinformation were correctly attributed to the misinformation source or, at least, ascribed to guesswork much more often than the central ones. As a consequence, after the SM task, the initially higher error rate for the peripheral item was even lower than that of the central item. Results convincingly show that the reasons for reporting misinformation, and correspondingly also the potential to avoid them in legal settings, depend on the centrality of the misinformation.     

Discrepancy detection and vulnerability to misleading postevent information

When people are exposed to misleading details after a witnessed event, they often claim that they saw the misleading details as part of the event. We refer to this as themisinformation effect. In four experiments, involving 570 subjects, we explored the role that discrepancy detection plays in the misinformation effect. Experiment 1 showed that subjects who naturally read a post-event narrative more slowly were more resistant to the effects of misleading information contained in the narrative. In Experiment 2, subjects who naturally read more slowly were more likely to detect a discrepancy between what they were reading and what was stored in their memory. In Experiment 3, subjects who were instructed to read slowly were more likely to detect a discrepancy than were those who were instructed to read quickly. In Experiment 4, subjects who were instructed to read slowly were more resistant to misleading postevent information. Taken together, these results suggest that longer reading times are associated with a greater scrutiny of postevent information. This leads to an increased likelihood that discrepancies will be detected and that the misinformation will be resisted.     

Misinformation revisited: New evidence on the suggestibility of memory

In three experiments involving a total of 623 subjects, a series of slides was shown depicting a student in a college bookstore stealing a variety of items. Next, subjects read a narrative describing the event that contained some misinformation and some neutral information about several critical details. Finally, subjects took a memory test. On this test, subjects were asked to list exemplars of 20 specified categories but were instructed not to list any items that they saw in the slide sequence. Analogous to Lindsay's (1990) adaptation of Jacoby, Woloshyn, and Kelley's (1989) “logic-ofopposition” paradigm, the tendency to report suggested details was thus set in opposition to the ability to remember the source of those details. Therefore, we interpreted failure to include suggested details as exemplars as evidence that subjects believed those details had been present in the event. Analysis of subjects' responses under opposition instructions suggests that some misled subjects come to genuinely believe that they saw items that, in reality, were only suggested to them.     

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.     

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

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

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

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