Empirical factors affecting memory in collaborative versus nominal groups

When individuals collaborate to try to retrieve some encoded information, not surprisingly, the collaborative group typically remembers more than does any individual. When the non-redundant output from the individuals is combined, however, this nominal group often, surprisingly, remembers more than does the collaborative group. This finding is known as collaborative inhibition. The finding of collaborative inhibition, that collaborative groups remember less would be predicted given the summed non-redundant memories of an equal number of individuals remembering alone, indicates that there is something about remembering in a collaborative group that impairs the performance of the individuals in that group. Research directed toward what that something is has focused on both social and cognitive factors, with the consensus being that cognitive factors play the more important role. An extensive body of work on this topic has accumulated over the past 25+ years, with researchers proposing theoretical explanations and generating empirical data revealing the conditions under which this collaborative inhibition is more versus less likely to occur. The purpose of this review is to summarize those empirical factors to provide a resource for researchers interested in pursuing this work.

Benefits and Detriments of Social Collaborative Memory in Turn-Taking and Directed Forgetting

Collaborative recall by groups of people can evoke both memory detriments (e.g., collaborative inhibition) and benefits (e.g., error pruning and post-collaborative memory benefit). Yet, it remains indeterminate whether these effects are due to the emotional valence of stimuli and/or the specific subtypes of episodic memory tested (i.e., item memory and source memory), and whether they are related to the research procedure of directed forgetting (DF). We introduced item-method DF into collaborative memory research using a turn-taking procedure. The to-be-recalled words were studied in different emotional valences and were followed by either an R or F cue, which, respectively, instructed participants to remember or forget the words presented. We conducted two recall sessions (Recall 1 and Recall 2) that included the two subtypes of episodic memory. Recall 1 was performed either individually or collaboratively, while Recall 2 was always performed individually. We observed three major findings: (a) a collaborative memory decrement - collaborative inhibition - was minimally affected in both item memory and source memory tasks by either the emotional valence of the stimuli or the DF cue; (b) a collaborative memory benefit - error pruning of item memory - persisted within both ongoing and post-collaboration, while error pruning of source memory only presented in ongoing collaboration, thus demonstrating the relevance of dual-process models that differentiate automatic familiarity and effortful recollection processes; and (c) there was no post-collaborative memory benefit, indicating the importance of the type of collaborative procedure. We discuss these results in terms of various theories, including the retrieval strategy disruption hypothesis (RSDH) which asserts that memory strategies tend to be disrupted in collaboration but are facilitated within post-collaboration. Also, we describe the implications of these results and directions for exploring other influential factors in future research.

Is Exposure to the Memories of Others a Necessary Precondition for Collaborative Inhibition?

In recall tasks, pooled individual productivity is generally greater than collaborative productivity, an effect called collaborative inhibition. This effect is believed to be caused by disruption of individual organizational strategies in the collaborative context due to exposure to the memories of others. The present study directly tested the exposure explanation. Three-person groups viewed a slide presentation and later recalled the content first as individuals, and subsequently as groups that were either exposed or not exposed to the memories of others. Results show that shielding participants from the contributions of others did not eliminate collaborative inhibition. The need to give more research attention to social factors is discussed.

Disrupters as Well as Monitors: Roles of Others During and After Collaborative Remembering in the DRM Procedure

Influence of others on true and inauthentic memory both during and after collaborative remembering have drawn extensive attention in recent years. Collaborative research has recorded three typical effects: collaborative inhibition and error pruning (i.e., nominal groups recall more true information but also bear higher erroneous intrusions than collaborative groups) during collaboration, as well as post-collaborative recall benefit after collaboration. This study introduced Deese-Roediger-McDermott (DRM) lists not only to investigate these phenomena in semantically related information, but also set a course to explore false memory in the collaborative context. Another issue is the sensitivity of these effects to different episodic memory tests (i.e., item memory and source memory tests). In views of these, the current study instructed participants to study several DRM lists and then recall previously studied words (item recall) together with their displayed colors (source retrieval) twice (Recall 1 and 2). Recall 1 was performed either individually or collaboratively, whereas Recall 2 was conducted individually. The cost of collaborative inhibition was obtained, along with three different beneficial effects: error pruning, false memory reduction, and post-collaborative recall benefit. Furthermore, the novel implication of the current study is that it reveals the sensitivity of collaborative inhibition and error pruning in DRM lists to testing conditions and demonstrates that the modulation of collaboration on false memory occurs in the same way both during and after collaboration. These results are discussed in terms of the retrieval strategy disruption hypothesis and other accounts.

The Many Faces of Part-List Cuing-Evidence for the Interplay Between Detrimental and Beneficial Mechanisms

If participants study a list of items and, at test, receive a random selection of the studied items as retrieval cues, then such cuing often impairs recall of the remaining items. This effect, referred to as part-list cuing impairment, is a well-established finding in memory research that, over the years, has been attributed to quite different cognitive mechanisms. Here, we provide a review of more recent developments in research on part-list cuing. These developments (i) suggest a new view on part-list cuing impairment and a critical role of encoding for the effect, (ii) identify conditions in which part-list cuing impairment can turn into part-list cuing facilitation, and (iii) relate research on part-list cuing to a phenomenon from social memory, known as collaborative inhibition. The recent developments also include a new multi-mechanisms account, which attributes the effects of cuing to the interplay between detrimental mechanisms—like blocking, inhibition, or strategy disruption—and beneficial mechanisms—like context reactivation. The account provides a useful theoretical framework to describe both older and newer findings. It may guide future work on part-list cuing and may also motivate new research on collaborative inhibition.

Enhancing individual and collaborative eyewitness memory with category clustering recall

Most crimes have multiple eyewitnesses. The police typically interview co-witnesses separately. In time-sensitive investigations, this could slow down evidence accumulation. Having co-witnesses collaboratively recall a crime could potentially expedite evidence accumulation. However, past research shows that collaborative group members often have conflicting retrieval strategies that disrupt each other, degrading overall recall. This cost could potentially be overcome by aligning group members' retrieval strategies with category clustering recall (CCR), which is a retrieval strategy where information is recalled from a series of forensically relevant categories (e.g., recalling the protagonists' appearance, then actions). This study examined the costs and benefits of collaborative eyewitness memory by having collaborative pairs of strangers, nominal pairs (i.e., two individuals whose recall is pooled) and lone individuals watch a crime and recall it using free recall or CCR. The collaborative pairs recalled the crime faster than the nominal pairs. They also recalled more correct information than individuals but less than nominal pairs, irrespective of the retrieval method. There is therefore a speed-recall completeness trade-off when collaborative groups recall crimes. Importantly, all participants recalled more correct information when using CCR. This provides initial evidence suggesting that CCR is superior to free recall. Further research examining CCR's benefits is recommended.

Conflict and metacognitive control: the mismatch-monitoring hypothesis of how others' knowledge states affect recall

Information about others' success in remembering is frequently available. For example, students taking an exam may assess its difficulty by monitoring when others turn in their exams. In two experiments, we investigated how rememberers use this information to guide recall. Participants studied paired associates, some semantically related (and thus easier to retrieve) and some unrelated (and thus harder). During a subsequent cued recall test, participants viewed fictive information about an opponent's accuracy on each item. In Experiment 1, participants responded to each cue once before seeing the opponent's performance and once afterwards. Participants reconsidered their responses least often when the opponent's accuracy matched the item difficulty (easy items the opponent recalled, hard items the opponent forgot) and most often when the opponent's accuracy and the item difficulty mismatched. When participants responded only after seeing the opponent's performance (Experiment 2), the same mismatch conditions that led to reconsideration even produced superior recall. These results suggest that rememberers monitor whether others' knowledge states accord or conflict with their own experience, and that this information shifts how they interrogate their memory and what they recall.

Learning and Remembering with Others: The Key Role of Retrieval in Shaping Group Recall and Collective Memory

People frequently collaborate to learn and remember information, and this may help groups create a shared representation of the world (i.e., collective memories). However, contrary to intuitions, collaboration also lowers group recall levels. Such impairment occurs regardless of whether people collaborate when first experiencing, or encoding, an event (the collaborative encoding deficit), or when retrieving, or remembering, the event (the collaborative inhibition effect). In understanding how collaboration impairs group recall and enhances collective or shared memories it remains unknown as to where collaboration exerts the greatest influence - at encoding or at retrieval - to shape these distinct phenomena. The current study simultaneously compared collaboration at these two stages and revealed the power of collaborative retrieval. Collaboration impaired the group recall product at both time points, but especially so at retrieval. Furthermore, only collaborative retrieval played a significant role in the formation of collective memories.