Memory distortion in group recall

Earlier we reported (Basden, Basden, Bryner, ...Thomas, 1997) that, in comparison with nominal groups (three people tested individually), three-person collaborative groups recalled fewer presented words but intruded more nonpresented words. In the present research, Experiment 1 showed that when presented words were associatively related to critical nonpresented words, collaboration inhibited recall of presented words but did not influence recall of critical nonpresented words. Experiment 2 showed that with categorized lists, recall of high taxonomic frequency critical nonpresented words was greater for collaborative groups than for nominal groups. Collaboration did not inhibit recall of presented words, presumably because guessing supplemented recall in collaborative groups. Greater false recall in collaborative than in nominal groups appears to result from activation of superordinate-to-item associations rather than item-to-item associations.     

集体记忆中的协作促进及其原因

摘 要 协作促进是指先前协作提取的经验对后续的个人提取具有积极影响。为了探讨协作促进产生的基本条件及其原因,本研究通过两个实验分别考察了小组的人数和回忆方式对协作促进的影响以及他人再现和交叉线索对协作促进的贡献。结果表明：无论小组的大小为2人组、3人组还是4人组,回忆方式为轮流回忆还是自由回忆均能产生协作促进,且轮流回忆的协作促进量要高于自由回忆的协作促进量;他人再现对协作促进的贡献大于交叉线索。这说明协作促进是一个稳定的现象,其主要原因是他人再现的作用。     

Group remembering: does social loafing underlie collaborative inhibition?

When people collaborate to recall information, they experience collaborative inhibition, a deficit in recall relative to nominal groups (the pooled, nonredundant recall of individuals working alone). That is, people recalling in groups do not perform up to their potential. Collaborative inhibition may be due to retrieval interference (e.g., B. H. Basden, D. R. Basden, S. Bryner, & R. L. Thomas, 1997) or to motivational factors such as social loafing in the group situation. Five experiments examined the role of motivational factors by varying monetary incentives, recall criterion, personal accountability, group cohesion, and group gender. Increasing motivation sometimes increased the overall level of recall but failed to eliminate the collaborative inhibition effect. The results suggest that collaboration interferes with an individual's ability to reconstruct his or her knowledge.     

The effect of information distribution on collaborative inhibition

Two experiments examined collaborative memory for information that was studied by all group members (shared items) and information that was studied by only a subset of group members (unshared items). In both experiments significant collaborative inhibition (reduced output of the collaborative groups relative to the pooled output of individuals) was obtained for both shared and unshared information. In Experiment 1 the magnitude of collaborative inhibition was larger for unshared items than for shared items, possibly because unshared items were less likely to be acknowledged and thus incorporated into the groups' recall. In Experiment 2 the magnitude of collaborative inhibition for shared and unshared information was equivalent once all participants were provided with the category name associated with the shared and unshared items. The results of the experiments are discussed in relation to the retrieval strategy disruption hypothesis of collaborative inhibition and the role of social process variables, such as acknowledgement, in influencing collaborative inhibition across situations involving memory of shared and unshared information.     

The effect of information distribution on collaborative inhibition

Two experiments examined collaborative memory for information that was studied by all group members (shared items) and information that was studied by only a subset of group members (unshared items). In both experiments significant collaborative inhibition (reduced output of the collaborative groups relative to the pooled output of individuals) was obtained for both shared and unshared information. In Experiment 1 the magnitude of collaborative inhibition was larger for unshared items than for shared items, possibly because unshared items were less likely to be acknowledged and thus incorporated into the groups’ recall. In Experiment 2 the magnitude of collaborative inhibition for shared and unshared information was equivalent once all participants were provided with the category name associated with the shared and unshared items. The results of the experiments are discussed in relation to the retrieval strategy disruption hypothesis of collaborative inhibition and the role of social process variables, such as acknowledgement, in influencing collaborative inhibition across situations involving memory of shared and unshared information.     

提取抑制对错误记忆的影响

该研究探讨提取抑制能否减少错误记忆的发生.以自编的DRM词表为实验材料,实验1采用有意遗忘范式（有意抑制）,实验2采用部分线索效应范式（无意抑制）.实验1结果发现：关键诱饵在“记住”条件下的错误回忆成绩显著高于“遗忘”条件下的错误回忆成绩;学过项目在“记住”条件下的正确回忆成绩显著高于“遗忘”条件下的正确回忆成绩.实验2结果发现：关键诱饵在“无部分线索”条件下的错误回忆成绩显著高于“部分线索”条件下的错误回忆成绩;学过项目在“无部分线索”条件下的正确回忆成绩显著高于“部分线索”条件下的正确回忆成绩.研究结果提示：有意和无意两种提取抑制都可以降低错误记忆,结果支持基于激活与监测的双加工理论的观点.     

Age differences in collaborative memory: the role of retrieval manipulations

In two experiments, we examined age differences in collaborative inhibition (reduced recall in pairs of people, relative to pooled individuals) across repeated retrieval attempts. Younger and older adults studied categorized word lists and were then given two consecutive recall tests and a recognition test. On the first recall test, the subjects were given free-report cued recall or forced-report cued recall instructions (Experiment 1) or free recall instructions (Experiment 2) and recalled the lists either alone or in collaboration with another subject of the same age group. Free-report cued recall and free recall instructions warned the subjects not to guess, whereas forcedreport cued recall instructions required them to guess. Collaborative inhibition was obtained for both younger and older adults on initial tests of free-report cued recall, forced-report cued recall, and free recall, showing that the effect generalizes across several tests for both younger and older adults. Collaborative inhibition did not persist on subsequent individual recall or recognition tests for list items. Older adults consistently falsely recalled and recognized items more than did younger adults, as had been found in previous studies. In addition, prior collaboration may exaggerate older adults’ tendency toward higher false alarms on a subsequent recognition test, but only after a free recall test. The results provide generality to the phenomenon of collaborative inhibition and can be explained by invoking concepts of strategy disruption and source monitoring.     

Study repetition and divided attention: Effects of encoding manipulations on collaborative inhibition in group recall

Two experiments tested the effects of encoding manipulations on group recall and on the magnitude of collaborative inhibition. Collaborative inhibition refers to the phenomenon where by a collaborative group recalls less than do the same number of individuals who work alone and then have their nonredundant responses pooled. Participants studied categorized word lists once or three times (Experiment 1) or under conditions of full versus divided attention (Experiment 2). Study repetition both improved retrieval organization in recall and attenuated collaborative inhibition, and divided attention encoding both reduced retrieval organization in recall and eliminated collaborative inhibition. These experiments are the first to focus on encoding variables and to show that collaborative inhibition can vary as a function of encoding manipulations.     

Transmitting false memories in social groups

In 2 experiments, subjects studied word lists drawn from Roediger and McDermott (1995) and then participated in perceived group recall (PGR) tests that were intended to lead each subject to believe that she or he was participating in collaborative recall in a 4-person group. Some of the lists were followed by PGR tests containing the nonpresented critical word, some lists were followed by PGR tests not containing the nonpresented critical word, and some lists were not followed by PGR tests. Subjects then completed individually administered recall tests and subsequent immediate or delayed recognition tests that required remember or know judgments. The major finding was that critical words contained within PGR tests were as likely to be falsely recalled, recognized, and consciously remembered as original list items. These findings show that false memories can be socially transmitted.     

The effects of social pressure on group recall

In two experiments, individual subjects worked in conjunction with two perceived group members to recall six 30-item categorized word lists. The perceived group members' recall levels were manipulated to establish either high or low group standards. After participating in the perceived group, subjects completed a surprise final individual recall test that covered all of the presented material. On the basis of the hypothesis that the subjects' performance would be affected by social pressure, it was predicted that subjects working in high-performing groups would recall more words than subjects working in low-performing groups on both the group recall tests and the final individual recall test. These predicted results were observed. Thus, a complete analysis of the group recall environment should include a consideration of conformity theory whereby subjects' memories can be affected by their group members' output levels.     

Exploring the relationship between retrieval disruption from collaboration and recall

When people recall together in a collaborative group they recall less than their potential. This phenomenon of collaborative inhibition is explained in terms of retrieval disruption. However, collaborative recall also re-exposes individuals to items recalled by others that they themselves might otherwise have forgotten. This re-exposure produces post-collaborative benefits in individual recall. The current study examined whether reduced retrieval disruption during group recall is related not only to less collaborative inhibition, but also to greater post-collaborative recall benefits. To test this we devised a paradigm to calculate the extent to which each individual experienced retrieval disruption during group recall. We also included two types of collaborative groups, one of which was expected to experience greater retrieval disruption than the other. Results suggest that the relationship between retrieval disruption and recall performance depends on the level at which retrieval disruption is measured. When retrieval disruption was assessed at the individual level, then minimising retrieval disruption was associated with higher recall (i.e., less collaborative inhibition and greater post-collaborative individual recall). However, when retrieval disruption was assessed at the group level there was no relationship with recall. Furthermore, the findings from this design suggest a role of cross-cueing in modulating group recall levels.     

协作抑制的作用机制：来自编码阶段的证据

协作抑制是指当人们在一个记忆小组中一起提取信息的时候,小组提取的信息总量比等量个体提取的信息总量要少。本研究采用经典的协作抑制研究范式和两次提取任务,考察编码方式和学习次数对协作提取任务的影响,进一步将考察协作抑制的产生机制作为总研究目的。结果表明,编码方式相同条件下出现协作抑制,而编码方式不同条件下协作抑制消失,显示协作抑制的出现与否依赖于认知条件的改变;无论是学习一次还是学习两次,在第一次小组提取中出现协作抑制,而在第二次个人提取中协作抑制消失,在使用困难学习材料时也得到同样的研究结果。研究结果支持协作抑制的提取策略破坏假说。     

Dissociative effects of true and false recall as a function of different encoding strategies

Goodwin, Meissner, and Ericsson (2001) proposed a path model in which elaborative encoding predicted the likelihood of verbalisation of critical, nonpresented words at encoding, which in turn predicted the likelihood of false recall. The present study tested this model of false recall experimentally with a manipulation of encoding strategy and the implementation of the process-tracing technique of protocol analysis. Findings indicated that elaborative encoding led to more verbalisations of critical items during encoding than rote rehearsal of list items, but false recall rates were reduced under elaboration conditions (Experiment 2). Interestingly, false recall was more likely to occur when items were verbalised during encoding than not verbalised (Experiment 1), and participants tended to reinstate their encoding strategies during recall, particularly after elaborative encoding (Experiment 1). Theoretical implications for the interplay of encoding and retrieval processes of false recall are discussed.     

Exploring the relationship between retrieval disruption from collaboration and recall

When people recall together in a collaborative group they recall less than their potential. This phenomenon of collaborative inhibition is explained in terms of retrieval disruption. However, collaborative recall also re-exposes individuals to items recalled by others that they themselves might otherwise have forgotten. This re-exposure produces post-collaborative benefits in individual recall. The current study examined whether reduced retrieval disruption during group recall is related not only to less collaborative inhibition, but also to greater post-collaborative recall benefits. To test this we devised a paradigm to calculate the extent to which each individual experienced retrieval disruption during group recall. We also included two types of collaborative groups, one of which was expected to experience greater retrieval disruption than the other. Results suggest that the relationship between retrieval disruption and recall performance depends on the level at which retrieval disruption is measured. When retrieval disruption was assessed at the individual level, then minimising retrieval disruption was associated with higher recall (i.e., less collaborative inhibition and greater post-collaborative individual recall). However, when retrieval disruption was assessed at the group level there was no relationship with recall. Furthermore, the findings from this design suggest a role of cross-cueing in modulating group recall levels.     

Children's collaborative recall of shared and unshared information

This study examined age differences in collaborative inhibition and the role of inter‐subjectivity, collective information sampling (CIS) and collaborative inhibition for the collaborative recall of shared and unshared information in groups of 7‐ and 9‐year‐old children. Three‐hundred and thirteen 7‐ and 9‐year‐old children recalled memorized wordlists either in real or nominal groups of three. All group members either recalled the same items, or each group member was given some unique items. Nine‐year‐olds, but not 7‐year‐olds, recalled significantly more items in nominal than real groups, a phenomenon called collaborative inhibition. Groups whose interactions were characterized by higher numbers of inter‐subjective exchanges recalled fewer words than groups low in inter‐subjectivity. In both age groups, a higher proportion of shared compared with unshared information was recalled consistent with processes of CIS. However, 7‐year‐olds recalled more unshared items than predicted, suggesting that collaborative inhibition additionally contributes to the recall of shared and unshared items.     

Recall order determines the magnitude of directed forgetting in the within-participants list method

In three experiments, we investigated the effect of recall order on directed forgetting when the within-participants list method is used. Experiment 1 showed that participants tend to recall to-be-remembered (R) items before to-be-forgotten (F) items when they can recall items in any order. In Experiment 2, recall order was manipulated (F-R or R-F). The results showed that only the R-F order led to directed forgetting. Finally, in Experiment 3, recall order was also manipulated, and half of the participants were explicitly instructed to use a relational strategy when both F and R items were presented. Again, only the R-F order led to directed forgetting. These results demonstrate that directed forgetting under the list method hinges on the output order in which participants recall the F and R information. Thus, output order should be taken into account by researchers investigating specific mechanisms that lead to directed forgetting.     

Comparison of output order in free recall

Two measures of output order in free recall were examined and shown to vary with characteristics of recall unrelated to output order. The output location of a subset of items in recall, using the standard recall rank measure and the “observed minus expected” score, varied both with number of items in the subset and total number of items recalled. A new measure of output order (the relative index of priority or RIP score) was proposed that is invariant with these characteristics of recall, providing an uncontaminated empirical index of the output location of a subset of items in the recall sequence.     

Retrieval dynamics in false recall: revelations from identifiability manipulations

The present study analyzed the retrieval dynamics of false recall, using an externalized free-recall task after participants studied Deese/Roediger–McDermott lists with high- and low-identifiable critical words. In Experiment 1, the memory test required participants to write down the words they remembered as having been presented in each list (recall output) plus any related words that came to mind (inclusion output). The results of the inclusion output showed that highly identifiable critical items were more frequently generated than less identifiable critical items, suggesting that highly identifiable critical words were more accessible in a first phase of retrieval. At the same time, the results of the recall output showed that highly identifiable critical items were less often falsely recalled than low-identifiable critical items, a replication of previous findings. In Experiment 2, self-reports corroborated that participants were using an editing strategy based on the identification and exclusion of critical words—that is, the identify-to-reject strategy. These results help us to more fully understand the identifiability effect and, beyond that, emphasize the importance of considering the intervening of dual processes of accessibility and error correction as a crucial feature in theoretical explanations of false memories.     

Output monitoring tests reveal false memories of memories that never existed

Three experiments were conducted to assess participants' beliefs about potential false memories that might have occurred during free recall tests. An input–output monitoring test was administered that required participants to discriminate between items that were studied and recalled, studied and not recalled, or were entirely new. Critical lures from Roediger and McDermott's (1995) paradigm were inserted into this test. The results demonstrated that participants believed erroneously recalled items were both studied and recalled. The intriguing finding was that unrecalled items were believed to have been studied approximately 80% of the time, and half of those were also believed to have been recalled. This result represents a dual false memory effect in which items were believed to have been studied and also to have been recalled. The ramifications of this new procedure are discussed in terms of proposed experiments that might clarify the genesis of these false memories.