Co‐Witness Confidence,Conformity, and Eyewitness Memory: An Examination of Normative and Informational Social Influences

We explored conformity and co‐witness confidence in eyewitness memory. Confederates provided misleading information and confidence ratings during a cued recall test, and participants publicly provided answers to this test in turn. Participants performed memory tests with a confederate, then completed individual memory tests. Results indicated that confederates who answered questions prior to participants impacted their public and private memory reports for accurate information but only impacted public reports for misleading information. Participants' confidence in their performance in the presence of a confederate mirrored the confederate's confidence levels, suggesting a confidence conformity effect. Results are explained in terms of differential effects of informational and normative influence for accuracy and confidence in co‐witness memory reports. Copyright © 2012 John Wiley & Sons, Ltd.     

Manipulating power can affect memory conformity

Memory is malleable and open to influence between encoding and retrieval. Information about a past event given to us by, for example, a co‐witness can be incorporated into our own memory reports. Pairs of participants were shown 50 photographs of faces, given a power task where one had to be a designer (low‐power) and one a judge (high‐power), and then given a recognition test where one partner had to answer before the other. The individuals in the low‐power group were more influenced by their partner's responses than those in the high‐power group. This has important forensic, educational and organisational applications and shows that memory conformity can be manipulated by power. Copyright © 2007 John Wiley & Sons, Ltd.     

Peer discussion affects children's memory reports

This study explored the memory conformity effect in children. Younger (6–7 years; n = 60) and older (11–12 years; n = 62) children watched a video individually (individual witness condition) or in dyads (co‐witness condition). The dyads believed that they were viewing the same video as the other member of the pair while in fact the saw different versions. Next, children in the individual witness condition answered questions, whereas children in the co‐witness condition discussed the event on the video with each other. Finally, all children completed an individual free and cued recall task. In the co‐witness condition, more than 60% of the children recalled at least one detail from the alternative video, whereas over 23% of the children in the individual witness condition reported such a detail. Moreover, in free recall—but not in cued recall—the memory conformity effect was stronger for older than for younger children. Copyright © 2007 John Wiley & Sons, Ltd.     

The Power of a Co‐witness: When More Power Leads to More Conformity

The effect of the power dynamic between co‐witnesses on memory conformity for images was investigated. Participant–confederate pairs were first presented with 50 images on a computer and then were randomly assigned to one of three social power role combinations analogous to those present in the workplace: manager and subordinate, subordinate and manager, or collaborators with equal power and status. After role assignment (but without ever engaging in the role‐related tasks), pairs were tested on whether each of 100 images (50 old and 50 new) had or had not been shown previously. Confederates always responded before participants. Subordinates were significantly less likely to conform than managers. Findings are discussed in light of the work‐related facet of social power and memory distortion. Copyright © 2013 John Wiley & Sons, Ltd.     

Comparing methods of encountering post‐event information: the power of co‐witness suggestion

The current study compared the effects of co‐witness information on memory with more widely studied methods of encountering post‐event information. Participants were shown a crime video and then exposed to both correct and incorrect post‐event information about the video through one of four methods: (1) leading questions, (2) media report, (3) indirect co‐witness information, or (4) co‐witness discussion. There was also a control condition in which participants did not receive any post‐event information. All participants were individually tested on their memories for the event 1 week later. Results suggest that co‐witness information had a particularly strong influence on eyewitness memory, whether encountered through co‐witness discussion or indirectly through a third party. That is, participants were more likely to report co‐witness information than post‐event information encountered through leading questions or a media report. Copyright © 2006 John Wiley & Sons, Ltd.     

Semantic context influences memory for verbs more than memory for nouns

Three experiments revealed that memory for verbs is more dependent on semantic context than is memory for nouns. The participants in Experiment 1 were asked to remember either nouns or verbs from intransitive sentences. A recognition test included verbatim sentences, sentences with an old noun and a new verb, sentences with an old verb and a new noun, and entirely new sentences. Memory for verbs was significantly better when the verb was presented with the same noun at encoding and at retrieval. This contextual effect was much smaller for nouns. Experiments 2 and 3 replicated this effect and provided evidence that context effects reflect facilitation from bringing to mind the same meaning of a verb at encoding and at retrieval. Memory for verbs may be more dependent on semantic context because the meanings of verbs are more variable across semantic contexts than are the meanings of nouns.     

The south beach study: Bystanders' memories are more malleable

People's reports are affected by what others say. The current study compared memory conformity effects of people who interacted with a confederate, and of bystanders to that interaction. A second goal was to observe if memory conformity occurs in a naturalistic setting. A male confederate approached a group of people at the beach and had a brief interaction. About a minute later a research assistant approached the group and administered a target‐absent lineup to each person in the group. Memory conformity was observed. Bystanders were twice as likely to conform as those who interacted with the confederate. Forensic investigators should take into consideration the role a person plays in an event when assessing eyewitness evidence. Copyright © 2010 John Wiley & Sons, Ltd.     

Memory conformity: can eyewitnesses influence each other's memories for an event?

The current study investigated memory conformity effects between individuals who witness and then discuss a criminal event, employing a novel procedure whereby each member of a dyad watches a different video of the same event. Each video contained unique items that were thus seen only by one witness. Dyads in one condition were encouraged to discuss the event before each witness (individually) performed a recall test, while in a control condition dyads were not allowed to discuss the event prior to recall. A significant proportion (71%) of witnesses who had discussed the event went on to mistakenly recall items acquired during the discussion. There were no age‐related differences in susceptibility to these memory conformity effects in younger (18–30 years) as compared to older (60–80 years) participants. Possible social and cognitive mechanisms underlying the distortions of memory due to conformity are discussed. Copyright © 2003 John Wiley & Sons, Ltd.     

Memory conformity: Disentangling the steps toward influence during a discussion

When two people see the same event and discuss it, one person’s memory report can influence what the other person subsequently claims to remember. We refer to this asmemory conformity. In the present article, two factors underlying the memory conformity effect are investigated. First, are there any characteristics of the dialogue that predict memory conformity? Second, is memory conformity differentially affected when information is encountered that omits, adds to, or contradicts originally encoded items? Participants were tested in pairs. The two members of each pair encoded slightly different versions of complex scenes and discussed them prior to an individual free recall test. The discussions were audiotaped, transcribed, and analyzed. Our most striking finding was that the witness initiating the discussion was most likely to influence the other witness’s memory report. Furthermore, witnesses were most likely to be influenced when an additional (previously unseen) item of information was encountered in the discussion.     

Social influences on reality-monitoring decisions

A modified Asch (1951) conformity paradigm was used to study the impact of social influence on reality-monitoring decisions about new items. Subjects studied pictures of some objects and imagined others. In a later test phase, they judged whether items had been perceived in the study phase, had been imagined, or were new. Critically, for some items, the subjects were informed of a confederate's response before rendering a judgment. Although the confederate was always correct when they responded to old items, for new items, the confederate responded perceived, imagined, or new, or did not respond (baseline). In two experiments, we show that memory for new items was influenced by an erroneous response of the confederate. Social conformity was reduced by undermining the credibility of the confederate (Experiments 1A and 1B), and the confederate's influence was evident even after there was only a 20-min delay between study and test (Experiment 2), when the subjects were 87% accurate on new baseline items. These experiments reveal the power of social influence on reality-monitoring accuracy and confidence.     

The effect of noun animacy on the processing of unambiguous sentences: Evidence from French relative clauses

It has previously been shown that moving images are remembered better than static ones. In two experiments, we investigated the basis for this dynamic superiority effect. Participants studied scenes presented as a single static image, a sequence of still images, or a moving video clip, and 3 days later completed a recognition test in which familiar and novel scenes were presented in all three formats. We found a marked congruency effect: For a given study format, accuracy was highest when test items were shown in the same format. Neither the dynamic superiority effect nor the study–test congruency effect was affected by encoding (Experiment 1) or retrieval (Experiment 2) manipulations, suggesting that these effects are relatively impervious to strategic control. The results demonstrate that the spatio-temporal properties of complex, realistic scenes are preserved in long-term memory.     

Combating Co‐witness contamination: Attempting to decrease the negative effects of discussion on eyewitness memory

Witnesses who discuss an event with others often incorporate misinformation encountered during the discussion into their memory of the event. Two experiments were conducted to establish whether this memory conformity also occurs in the context of an interview and whether it is possible to reduce the effect. Participants viewed a crime‐video which they then discussed with a co‐witness. Some participants were warned they may have been exposed to misinformation during the discussion before all were interviewed individually. In Experiment 1, participants made remember/know judgments about each component of their free recall, and in Experiment 2 they were asked to indicate the source of their memories. Co‐witness information was incorporated into participants' testimony, and this effect could not be significantly reduced using warnings and source‐monitoring instructions. Remember/know judgments may be useful in distinguishing ‘real’ memories from false memories. We make some recommendations regarding the interviewing of witnesses. Copyright © 2009 John Wiley & Sons, Ltd.     

Central load reduces peripheral processing: Evidence from incidental memory of background speech

Is there a trade‐off between central (working memory) load and peripheral (perceptual) processing? To address this question, participants were requested to undertake an n‐back task in one of two levels of central/cognitive load (i.e., 1‐back or 2‐back) in the presence of a to‐be‐ignored story presented via headphones. Participants were told to ignore the background story, but they were given a surprise memory test of what had been said in the background story, immediately after the n‐back task was completed. Memory was poorer in the high central load (2‐back) condition in comparison with the low central load (1‐back) condition. Hence, when people compensate for higher central load, by increasing attentional engagement, peripheral processing is constrained. Moreover, participants with high working memory capacity (WMC) – with a superior ability for attentional engagement – remembered less of the background story, but only in the low central load condition. Taken together, peripheral processing – as indexed by incidental memory of background speech – is constrained when task engagement is high.     

Sub-chronic rolipram treatment leads to a persistent improvement in long-term object memory in rats

In the present study the effects of sub-chronic rolipram treatment in an object recognition task in 3-month-old male rats were investigated. Rats remember which object they have explored in a previous trial (T1) when they are tested 1 h later (T2). However, when tested 24 h later, they do not remember which object was presented to them in the first trial. Drug treatments may improve discrimination performance after 24 h, i.e., improve memory for the familiar object. Rats were sub-chronically treated with 0.5 mg/kg rolipram (p.o.) for five consecutive days and tested with a 24 h delay between T1 and T2. Memory performance in the object recognition task was assessed before, during and after sub-chronic treatment. In addition, we investigated whether the timing of the final dose, i.e., 24, 1, or 6 h before training, had an effect on memory performance. During sub-chronic treatment, i.e., after 2-3 days of rolipram treatment, moderate effects on memory performance were observed. Regardless of when the final administration was given, sub-chronic rolipram treatment improved long-term memory performance. Since plasma and brain rolipram levels were undetectable at 24 h before the test, and acute treatment with rolipram 24 h before training had no effects, the observed memory enhancement cannot be attributed to acute rolipram effects. The long-term memory enhancing effects of rolipram might be explained by long-lasting neuronal changes by the chronic treatment due to recurring activation of the cAMP/PKA/CREB pathway leading to CREB phosphorylation.     

Influences of temporal factors on memory conjunction errors

Subjects viewed a series of faces presented two at a time for 16 seconds. Following either a 15‐minute (Experiment 1) or 24‐hour (Experiment 2) retention interval they received a recognition test that included old faces as well as faces constructed by recombining features from simultaneously presented study faces (simultaneous‐conjunction condition), faces from successive pairs (near‐conjunction condition), and faces that were two pairs apart (far‐conjunction condition). In Experiment 1, false alarm rates decreased as the temporal distance between the relevant study faces increased. In Experiment 2, the false alarm rate in the simultaneous‐conjunction condition was equal to the hit rate for old faces, and the false alarm rates for the other conditions was much lower. There was no effect of serial position during the study phase on the likelihood that parts of a face would later be miscombined to produce a recognition error in either experiment. The results suggest that witnesses to a crime are more likely to miscombine features of a to‐be‐remembered stimulus with those of another stimulus that was simultaneously present at the crime scene than with those of a stimulus encountered either earlier or later, especially when the test is delayed. Copyright © 2000 John Wiley & Sons, Ltd.     

Repeated reminders inrease the speed of memory retrieval by 3‐month‐old infants

In two experiments, we examined the effect of repeated reminder treatments on the speed of memory retrieval by 3‐month‐old human infants. Infants were trained for two consecutive days to kick their feet to produce movement in an overhead mobile. Infants in the one‐reminder condition received a 3 min reminder treatment 13 days after the conclusion of training. Infants in the two‐reminder condition received one 3 min reminder treatment 6 days after the conclusion of training and a second reminder treatment 7 days later (i.e. 13 days following the conclusion of training). Infants in the no‐reminder control condition were not exposed to the reminder prior to the long‐term retention test. In the absence of a reminder treatment, infants exhibited complete forgetting during the long‐term test. Infants exposed to one reminder exhibited retention when tested 24 h after their only reminder, but not when tested earlier. Infants exposed to two reminder treatments, on the other hand, exhibited retention when tested 1, 4 or 24 h after their second reminder treatment. We conclude that the opportunity to retrieve the memory on a prior occasion facilitated subsequent memory retrieval.     

The effect of cross‐examination on the accuracy of adult eyewitness testimony

Cross‐examination permits styles of questioning that increase eyewitness error (e.g. leading questions). Previous research has shown that under cross‐examination children change many of their initially accurate answers. An experiment is reported in which the effect of cross‐examination on accuracy of adult eyewitness testimony was investigated. Twenty‐two student witnesses watched a video of a staged theft, either in pairs, or individually. Paired witnesses discussed the video with their co‐witnesses, but did not know they had seen slightly different versions. Participants in the co‐witness condition demonstrated memory conformity and recalled less accurately than witnesses in the control condition. After approximately 4 weeks all participants were cross‐examined by a trainee barrister. Following cross‐examination there was no difference in accuracy between the two experimental groups. Witnesses in both conditions made many changes to their previous reports by altering both initially correct and incorrect answers. The results demonstrate negative effects of cross‐examination on the accuracy of adult eyewitness testimony. Copyright © 2010 John Wiley & Sons, Ltd.     

Positive and negative sources of emotional arousal enhance long-term word-list retention when induced as long as 30 min after learning

The consolidation of newly formed memories occurs slowly, allowing memories to be altered by experience for some time after their formation. Various treatments, including arousal, can modulate memory consolidation when given soon after learning, but the degree of time-dependency of these treatments in humans has not been studied. Thus, 212 participants learned a word list, which was followed by either a positively or negatively valenced arousing video clip (i.e., comedy or surgery, respectively) after delays of 0, 10, 30 or 45 min. Arousal of either valence induced up to 30 min after learning, but not after 45 min, significantly enhanced one-week retrieval. The findings support (1) the time-dependency of memory modulation in humans and (2) other studies that suggest that it is the degree of arousal, rather than valence that modulates memory. Important implications for developing memory intervention strategies and for preserving and validating witness testimony are discussed.     

Effects of correspondence between encoding and retrieval organization in social memory

Memory research has shown impaired recall performance when a subset of the studied stimuli is presented at recall (the part-list cueing effect, Slamecka, 1968) or when the recall is collaborative (collaborative-inhibition effect, Weldon & Bellinger, 1997). In two experiments we explore these effects in an impression-formation context and compare two prominent accounts (retrieval blocking versus strategy disruption) for them. We varied the correspondence between item organization at encoding and retrieval, either by manipulating the organization of part-list cues (Experiment 1) or the organization of the stimulus list that was later recalled collaboratively (Experiment 2). Results showed that when encoding and recall organizations did not correspond recall was impaired, replicating part-list cueing and collaborative-inhibition effects. However, when encoding and retrieval organization corresponded, these effects were greatly reduced. Such results support the recall strategy disruption hypothesis and challenge the retrieval blocking account. Implications for understanding memory in a social context are discussed.