Children's eyewitness reports after exposure to misinformation from parents

This study examined how misleading suggestions from parents influenced children's eyewitness reports. Children (3 to 8 years old) participated in science demonstrations, listened to their parents read a story that described experienced and nonexperienced events, and subsequently discussed the science experience in two follow-up interviews. Many children described fictitious events in response to open-ended prompts, and there were no age differences in suggestibility during this phase of the interview. Accuracy declined markedly in response to direct questions, especially for the younger children. Although the older children retracted many of their false reports after receiving source-monitoring instructions, the younger children did not. Path analyses indicated that acquiescence, free recall, and source monitoring all contribute to mediating patterns of suggestibility across age. Results indicate that judgments about the accuracy of children's testimony must consider the possibility of exposure to misinformation prior to formal interviews.     

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.     

Pilgrims sailing the Titanic: Plausibility effects on memory for misinformation

People rely on information they read even when it is inaccurate (Marsh, Meade, & Roediger, Journal of Memory and Language 49:519–536, 2003), but how ubiquitous is this phenomenon? In two experiments, we investigated whether this tendency to encode and rely on inaccuracies from text might be influenced by the plausibility of misinformation. In Experiment 1, we presented stories containing inaccurate plausible statements (e.g., “The Pilgrims’ ship was the Godspeed”), inaccurate implausible statements (e.g., . . . the Titanic), or accurate statements (e.g., . . . the Mayflower). On a subsequent test of general knowledge, participants relied significantly less on implausible than on plausible inaccuracies from the texts but continued to rely on accurate information. In Experiment 2, we replicated these results with the addition of a think-aloud procedure to elicit information about readers’ noticing and evaluative processes for plausible and implausible misinformation. Participants indicated more skepticism and less acceptance of implausible than of plausible inaccuracies. In contrast, they often failed to notice, completely ignored, and at times even explicitly accepted the misinformation provided by plausible lures. These results offer insight into the conditions under which reliance on inaccurate information occurs and suggest potential mechanisms that may underlie reported misinformation effects.     

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.     

Oscillator-based memory for serial order

A computational model of human memory for serial order is described (OSCillator-based Associative Recall [OSCAR]). In the model, successive list items become associated to successive states of a dynamic learning-context signal. Retrieval involves reinstatement of the learning context, successive states of which cue successive recalls. The model provides an integrated account of both item memory and order memory and allows the hierarchical representation of temporal order information. The model accounts for a wide range of serial order memory data, including differential item and order memory, transposition gradients, item similarity effects, the effects of item lag and separation in judgments of relative and absolute recency, probed serial recall data, distinctiveness effects, grouping effects at various temporal resolutions, longer term memory for serial order, list length effects, and the effects of vocabulary size on serial recall.     

Similarity of encoding context does not influence resistance to memory impairment following misinformation

Several recent studies have shown that exposure to verbal misleading post-event information does not impair subjects' ability to retrieve originally seen details. Two experiments were conducted to test the hypothesis that subjects would be more susceptible to memory impairment if the original and misleading information were presented in similar contextual formats. The results showed that misleading information did not lead to memory impairment when both original and misleading information were presented in the context of slides (Experiment 1) or when both original and misleading information were presented in the context of narratives (Experiment 2). Furthermore, resistance to memory impairment was observed both at relatively low levels of memory for the original information (Experiment 1) and at relatively high levels of memory for the original information (Experiment 2). The implications of the present results for interference principles of forgetting are discussed.     

Changing the criterion for memory conformity in free recall and recognition

People's responses during memory studies are affected by what other people say. This memory conformity effect has been shown in both free recall and recognition. Here we examine whether accurate, inaccurate, and suggested answers are affected similarly when the response criterion is varied. In the first study, participants saw four pictures of detailed scenes and then discussed the content of these scenes with another participant who saw the same scenes, but with a couple of details changed. Participants were either told to recall everything they could and not to worry about making mistakes (lenient), or only to recall items if they were sure that they were accurate (strict). The strict instructions reduced the amount of inaccurate information reported that the other person suggested, but also reduced the number of accurate details recalled. In the second study, participants were shown a large set of faces and then their memory recognition was tested with a confederate on these and fillers. Here also, the criterion manipulation shifted both accurate and inaccurate responses, and those suggested by the confederate. The results are largely consistent with a shift in response criterion affecting accurate, inaccurate, and suggested information. In addition we varied the level of secrecy in the participants’ responses. The effects of secrecy were complex and depended on the level of response criterion. Implications for interviewing eyewitnesses and line-ups are discussed.     

Changing the criterion for memory conformity in free recall and recognition

People's responses during memory studies are affected by what other people say. This memory conformity effect has been shown in both free recall and recognition. Here we examine whether accurate, inaccurate, and suggested answers are affected similarly when the response criterion is varied. In the first study, participants saw four pictures of detailed scenes and then discussed the content of these scenes with another participant who saw the same scenes, but with a couple of details changed. Participants were either told to recall everything they could and not to worry about making mistakes (lenient), or only to recall items if they were sure that they were accurate (strict). The strict instructions reduced the amount of inaccurate information reported that the other person suggested, but also reduced the number of accurate details recalled. In the second study, participants were shown a large set of faces and then their memory recognition was tested with a confederate on these and fillers. Here also, the criterion manipulation shifted both accurate and inaccurate responses, and those suggested by the confederate. The results are largely consistent with a shift in response criterion affecting accurate, inaccurate, and suggested information. In addition we varied the level of secrecy in the participants' responses. The effects of secrecy were complex and depended on the level of response criterion. Implications for interviewing eyewitnesses and line-ups are discussed.     

Traveling economically through memory space: Characterizing output order in memory for serial order

How do people report the contents of short-term memory when information about order must be retained but items can be retrieved in any order? We report an experiment using an unconstrained reconstruction task in which people can report list items in any order but must place them in their correct serial positions. We found (1) a tendency to report recent items first in immediate but not in delayed reconstruction, (2) a tendency to recall temporally isolated items first, (3) a preference for forward recall order, and (4) a preference for output orders that minimize the length of the path that must be traversed through memory space during retrieval. The results constrain most current models of short-term memory in which retrieval is ballistic and is assumed to run to completion autonomously once initiated.     

Initial codes for order in memory

The roles of positional and associative information in preserving the order of short sequences of items were investigated either by presenting an item in the same serial position on successive trials (position transfer), or by presenting the same pair of items in adjacent but shifted positions on successive trials (association transfer). While Experiment I found that positive transfer of position information occurred after just one repetition of an item in the same serial position, Experiment II found no evidence for association transfer after a single trial. If an item is presented in the same position, or if a pair of items are presented in adjacent positions on several successive trials, position transfer effects built up more rapidly than association transfer effects (Experiments III and IV). However, the rate at which association transfer effects are established depends on the type of item used, with lists of concrete words showing rapid establishment of associations (Experiment V) but lists of digits showing only slow development of associations (Experiment IV). It was concluded that serial order may be preserved both by positional and associative codes, but the establishment of an associative code is linked to the extraction of information about the items themselves.     

How to protect eyewitness memory against the misinformation effect: A meta-analysis of post-warning studies

Four decades of research and hundreds of studies speak to the power of post-event misinformation to bias eyewitness accounts of events (see e.g., Loftus’ summary, 2005). A subset of this research has explored if the adverse influence of misinformation on remembering can be undone or at least reduced through a later warning about its presence. We meta-analyzed 25 such post-warning studies (including 155 effect sizes) to determine the effectiveness of different types of warnings and to explore moderator effects. Key findings were that (1) post-warnings are surprisingly effective, reducing the misinformation effect to less than half of its size on average. (2) Some types of post-warning (following a theoretical classification) seem to be more effective than others, particularly studies using an enlightenment procedure (Blank, 1998). (3) The post-warning reduction in the misinformation effect reflects a specific increase in misled performance (relative to no warning), at negligible cost for control performance. We conclude with a discussion of theoretical and practical implications.     

Regional cerebral blood flow and verbal memory after chronic exposure to organic solvents

Regional cerebral blood flow (rCBF; 133Xe-inhalation method) was investigated in 32 industrial workers (age: 51 +/- 9 years) who had been exposed to organic solvents during an average of 24.5 years. The measurements were made at rest and during learning of associated word pairs. The resting flow level was 17% lower than expected for normal subjects of similar age and the activation-induced changes of rCBF during the test lacked the frontal activation normally seen. Significant correlations between age, length of exposure, and rCBF level were found. In order to control for the age factor, results were also calculated from two subgroups of similar age but with very different levels of exposure (13 and 31 years of average exposure). The two groups differed only slightly in resting rCBF. A marked difference was, however, seen during activation, with significant post-central flow increases recorded in the lower-exposed group only. The results indicate the potential of the rCBF method for elucidating functional cortical changes related to neurotoxic effects of organic solvents.     

Regularization in short-term memory for serial order

Previous research has shown that short-term memory for serial order can be influenced by background knowledge concerning regularities of sequential structure. Specifically, it has been shown that recall is superior for sequences that fit well with familiar sequencing constraints. The authors report a corresponding effect pertaining to serial recall errors. Undergraduate participants performed immediate serial recall on sequences of pseudowords generated on the basis of an artificial grammar. After extensive experience with this material, recall errors displayed a bias toward regularizing responses, response sequences more probable, with respect to the artificial grammar, than the originally presented stimulus sequence. This regularization effect squares well with recent trace redintegration and Bayesian models of serial recall, and appears to represent an analog of the schema-based error patterns observed in other domains of memory.     

Working memory performance after acute exposure to the cold pressor stress in healthy volunteers

Effects of acute stress exposure on learning and memory have been frequently studied in both animals and humans. However, only a few studies have focused specifically on working memory performance and the available data are equivocal. The present study examined working memory performance during the Sternberg item recognition task after exposure to a predominantly adrenergic stressor. Twenty four healthy subjects were randomly assigned to a stress group or a control group. The stress group was exposed to the cold pressor stress test (CPS; i.e. insertion of the dominant hand into ice water for 60s), while 37 °C warm water was used with the control group. Twenty minutes after the stress exposure, working memory performance was tested with the Sternberg item recognition task with three levels of cognitive load. Sympathetic nervous system and hypothalamic pituitary adrenocortical (HPA) axis activation during CPS, were assessed by measuring heart rate and salivary cortisol before and during (heart rate) or 30 min after (cortisol) the stress procedure. Exposure to the CPS test was associated with a significant increase in heart rate but no increase in salivary cortisol. Participants exposed to the stress procedure showed significantly shorter reaction times during trials with higher cognitive load but tended to show higher false alarm rates than control subjects. The present results indicate that exposure to CPS can be associated with signs of both enhanced and impaired working memory performance. The observed behavioral pattern might represent a form of streamlined information processing advantageous in a threatening situation.     

Progressive elaboration and memory for order in children

Three experiments were conducted investigating memory for items and order in a progressive elaboration paired-associates task. For all subjects retention of item information was improved by the use of progressively elaborated interactions relative to a no-elaboration control condition. For second and fourth graders, retention of order information depended upon the type of elaboration. If successive interactions were added in a logical temporal order, retention (of order information) was superior to the case where the successive interactions were added in a random order. This effect was not obtained with kindergarten children. In the second and third experiments, kindergarteners were instructed regarding the sequencing of the successive items, and results similar to those obtained with older children ensued. The data were discussed in terms of Tulving's distinction between episodic and semantic memory.     

Evidence for modality-independent order coding in working memory

The aim of the present study was to investigate the representation of serial order in working memory, more specifically whether serial order is coded by means of a modality-dependent or a modality-independent order code. This was investigated by means of a series of four experiments based on a dual-task methodology in which one short-term memory task was embedded between the presentation and recall of another short-term memory task. Two aspects were varied in these memory tasks—namely, the modality of the stimulus materials (verbal or visuo-spatial) and the presence of an order component in the task (an order or an item memory task). The results of this study showed impaired primary-task recognition performance when both the primary and the embedded task included an order component, irrespective of the modality of the stimulus materials. If one or both of the tasks did not contain an order component, less interference was found. The results of this study support the existence of a modality-independent order code.     

Evidence for modality-independent order coding in working memory

The aim of the present study was to investigate the representation of serial order in working memory, more specifically whether serial order is coded by means of a modality-dependent or a modality-independent order code. This was investigated by means of a series of four experiments based on a dual-task methodology in which one short-term memory task was embedded between the presentation and recall of another short-term memory task. Two aspects were varied in these memory tasks--namely, the modality of the stimulus materials (verbal or visuo-spatial) and the presence of an order component in the task (an order or an item memory task). The results of this study showed impaired primary-task recognition performance when both the primary and the embedded task included an order component, irrespective of the modality of the stimulus materials. If one or both of the tasks did not contain an order component, less interference was found. The results of this study support the existence of a modality-independent order code.     

The effect of enactment on memory for order

The effect of enactment on memory for serial order was investigated in two experiments. In both experiments a reconstruction task was used to separate order from item information. In Experiment 1 enactment and test information was manipulated between groups. For subjects who had not been informed about the reconstruction test, performance of verbal and motor groups was similar with regard to both serial-position curves and overall performance. For subjects who knew beforehand that they would be tested for memory of the order of the action events, performance in the verbal condition was significantly better than in the motor condition. In Experiment 2, the reversed enactment effect for test-informed subjects was replicated with a within-subjects design. The results agree with Engelkamp and Zimmer's (1984, 1994) position that enactment serves exclusively to enhance item information, and indicate that subjects have less control over the encoding processes when they are enacting than during verbal encoding (cf. Cohen, 1981).     

Time,space, and memory for order

Information about the order of items in a sequence can be conveyed either spatially or temporally. In the present investigation, we examined whether these different modes of presentation map onto compatible mental representations of serial order. We examined this issue in three immediate serial-recall experiments, in which participants recalled lists of letters in the temporal order in which they had appeared. Each letter in a to-be-remembered sequence was presented in a unique spatial position, with the order of these spatial positions progressing from either left to right or right to left. In this way, the visually presented lists contained both temporal and spatial order information. Recall of the temporal order information was more accurate with congruent spatial order information—that is, when the letters progressed from left to right, following the typical reading direction of English—than when the spatial order information was incongruent. These results suggest compatible representations of serial order when sequences are conveyed spatially and temporally.     

Short-term recognition memory for serial order and timing

Recent evidence suggests that a common temporal representation underlies memory for serial order of items in a sequence, and the timing of items in a sequence. This stands in contrast to other data suggesting a reliance on only ordinal information in short-term memory tasks. An experiment is reported here in which participants were post cued to perform a comparison between a probe and study list of items irregularly spaced in time, on the basis of order or temporal information.Participants' performance on theserial recognition task was notaffected by the temporal proximity of items, although participants were able to use temporal information to perform a temporal recognition task. Application of a temporal matching model of serial and temporal recognition suggests that although participants were able to remember the timing of items, this memory for timing was unlikely to determine serial recognition performance. The results suggest a dissociation between ordinal and temporal information in short-term memory.