Effects of repeated collaborative retrieval on individual memory vary as a function of recall versus recognition tasks

Our research examines how prior group collaboration modulates later individual memory. We recently showed that repeated collaborative recall sessions benefit later individual recall more than a single collaborative recall session (Blumen & Rajaram, 2008). Current research compared the effects of repeated collaborative recall and repeated collaborative recognition on later individual recall and later individual recognition. A total of 192 participants studied a list of nouns and then completed three successive retrieval sessions in one of four conditions. While two collaborative recall sessions and two collaborative recognition sessions generated comparable levels of individual recall (CRecall-CRecall-I Recall ～ CRecognition-CRecognition-I Recall , Experiment 1a), two collaborative recognition sessions generated greater levels of individual recognition than two collaborative recall sessions (CRecognition-CRecognition- IRecognition > CRecall-CRecall- I Recognition , Experiment 1b). These findings are discussed in terms of two opposing mechanisms that operate during collaborative retrieval—re-exposure and retrieval disruption—and in terms of transfer-appropriate processing across collaborative and individual retrieval sessions.     

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.     

Optimal foraging in semantic memory

Do humans search in memory using dynamic local-to-global search strategies similar to those that animals use to forage between patches in space? If so, do their dynamic memory search policies correspond to optimal foraging strategies seen for spatial foraging? Results from a number of fields suggest these possibilities, including the shared structure of the search problems-searching in patchy environments-and recent evidence supporting a domain-general cognitive search process. To investigate these questions directly, we asked participants to recover from memory as many animal names as they could in 3 min. Memory search was modeled over a representation of the semantic search space generated from the BEAGLE memory model of Jones and Mewhort (2007), via a search process similar to models of associative memory search (e.g., Raaijmakers & Shiffrin, 1981). We found evidence for local structure (i.e., patches) in memory search and patch depletion preceding dynamic local-to-global transitions between patches. Dynamic models also significantly outperformed nondynamic models. The timing of dynamic local-to-global transitions was consistent with optimal search policies in space, specifically the marginal value theorem (Charnov, 1976), and participants who were more consistent with this policy recalled more items.     

In-home cognitive training with older married couples: individual versus collaborative learning

Research has demonstrated that older adults' cognitive performance can be enhanced via formal intervention, as well as more informal intervention including collaboration or working with a partner. The current study investigated the effects of an inductive reasoning training program adapted for in-home use among older adults assigned to individual training (n = 30), collaborative training (n = 34), or a no-treatment control group (n = 34). The training consisted of 10 sessions, and all participants completed a pretest followed by a post-test 6 weeks later. Findings suggest that older adults could effectively "train themselves" without the guidance of a formal instructor. The results, however, did not indicate immediate added benefit in reasoning performance for collaborative versus individual training using the current reasoning program.     

Parallel versus serial processing and individual differences in high-speed search in human memory

Many mental tasks that involve operations on a number of items take place within a few hundred milliseconds. In such tasks, whether the items are processed simultaneously (in parallel) or sequentially (serially) has long been of interest to psychologists. Although certain types of parallel and serial models have been ruled out, it has proven extremely difficult to entirely separate reasonable serial and limited-capacity parallel models on the basis of typical data. Recent advances in theory-driven methodology now permit strong tests of serial versus parallel processing in such tasks, in ways that bypass the capacity issue and that are distribution and parameter free. We employ new methodologies to assess serial versus parallel processing and find strong evidence for pure serial or pure parallel processing, with some striking apparent differences across individuals and interstimulus conditions.     

Order effects and memory for evidence in individual versus group decision making in auditing

Sequential processing of evidence may lead to recency effect, a potential bias in judgment. The present research seeks to extend the literature on recency effects by assessing the potential moderating influence of team work: whether group decision making moderates the severity of recency effects predicted by Hogarth and Einhorn (1992), and whether group processing influences the accuracy of, and confidence in memory for evidence. Experienced auditors from a Big‐6 accounting firm made audit judgments, either individually or as groups. They were randomly assigned to one of two levels of evidence presentation order. After performing the judgment task, participants completed two evidence recognition tests. Consistent with prior findings, recency effects on judgments were observed, but only for individuals. Group judgments or audit reports were not affected by recency. Order effects, however, did not translate into different choices of audit reports, and did not persist in memories of either individuals or groups. As expected, group memory was more accurate than individual memory and groups were more confident than individuals. Overall, confidence in accurate memories was greater than in inaccurate ones. Copyright © 1999 John Wiley & Sons, Ltd.     

Collaborative remembering revisited: Study context access modulates collaborative inhibition and later benefits for individual memory

Collaborating groups typically show reduced recall relative to nominal groups, i.e., to the cumulated non-redundant recall of the same number of people remembering in isolation—a finding termed collaborative inhibition. Motivated by the results of several previous studies, this study examined in two experiments whether access to study context at test influences the effects of collaboration. In both experiments, subjects collaborated in triads or recalled previously studied material in isolation. Experiment 1 applied short versus prolonged retention intervals to vary access to study context at test, whereas Experiment 2 used the list-method directed forgetting task and applied remember versus forget instructions to modulate context access. In both experiments, collaborative inhibition was present when access to study context at test was intact (i.e., after the short delay and the remember instruction) but was eliminated when the access was impaired (i.e., after the prolonged delay and the forget instruction). Also, post-collaborative gains for individual recall were greater when context access was impaired and collaborative inhibition was eliminated. The findings demonstrate a critical role of access to study context at test for collaborative inhibition, indicating that impaired context access may reflect a general boundary condition for the recall impairment. The possible role of context reactivation processes for beneficial effects of social recall is discussed.     

The dynamics of infant visual foraging

Human infants actively forage for visual information from the moment of birth onward. Although we know a great deal about how stimulus characteristics influence looking behavior in the first few postnatal weeks, we know much less about the intrinsic dynamics of the behavior. Here we show that a simple stochastic dynamical system acts quantitatively like 4-week-old infants on a range of measures if there is hysteresis in the transitions between looking and looking away in the model system. The success of this simple three-parameter model suggests that visual foraging in the first few weeks after birth may be influenced more by noise and hysteresis in underlying neural mechanisms than by how infants process visual information after a look begins.     

Remembering and retelling stories in individual and collaborative contexts

Collaborative cognition, in which two or more people work together on a cognitive task, may be typical of everyday life, and may even represent an important aspect of everyday cognitive adaptation for older adults. We examined collaborative memory for stories by comparing younger (n = 64) and older (n = 66) individuals and dyads with collaborative performance produced by married spouses and stranger dyads. Overall, across four collaborative recall products (two positive and two negative performance indicators), some evidence for our hypothesis of general or selective collaborative effectiveness was observed. Moreover, such evidence was obtained at both an immediate and delayed recall episode. Discussion includes applications, limitations and suggestions for future research. Copyright © 2008 John Wiley & Sons, Ltd.     

Indexing individual objects in infant working memory

Currently there are disputes in the infancy literature concerning when infants are first able to individuate physical objects by their features or properties. This issue has taken on new significance following claims that individuation by feature is linked to the emergence of object kind concepts toward the end of the first year. Needham (2001, this issue) presents evidence that infants as young as 4.5 months old can individuate objects by feature. We locate this controversy within the framework of brain mechanisms that index or track individual objects, drawing upon theories of attention and working memory developed in the study of adults. We find that Needham's work contributes to two issues: categorization and the effect of object history on the individuation of objects in a complex display.     

Different importance of the volatile and non-volatile fractions of an olfactory signature for individual social recognition in rats versus mice and short-term versus long-term memory

When tested in the olfactory cued social recognition/discrimination test, rats and mice differ in their retention of a recognition memory for a previously encountered conspecific juvenile: Rats are able to recognize a given juvenile for approximately 45 min only whereas mice show not only short-term, but also long-term recognition memory (≥ 24 h). Here we modified the social recognition/social discrimination procedure to investigate the neurobiological mechanism(s) underlying the species differences. We presented a conspecific juvenile repeatedly to the experimental subjects and monitored the investigation duration as a measure for recognition. Presentation of only the volatile fraction of the juvenile olfactory signature was sufficient for both short- and long-term recognition in mice but not rats. Applying additional volatile, mono-molecular odours to the "to be recognized" juveniles failed to affect short-term memory in both species, but interfered with long-term recognition in mice. Finally immunocytochemical analysis of c-Fos as a marker for cellular activation, revealed that juvenile exposure stimulated areas involved in the processing of olfactory signals in both the main and the accessory olfactory bulb in mice. In rats, we measured an increased c-Fos synthesis almost exclusively in cells of the accessory olfactory bulb. Our data suggest that the species difference in the retention of social recognition memory is based on differences in the processing of the volatile versus non-volatile fraction of the individuals' olfactory signature. The non-volatile fraction is sufficient for retaining a short-term social memory only. Long-term social memory - as observed in mice - requires a processing of both the volatile and non-volatile fractions of the olfactory signature.     

Patterns of engagement: the relationship between efficacy beliefs and task engagement at the individual versus collective level

This study examines the relationship between efficacy beliefs and task engagement in and over time, at both the individual and collective levels. We conducted latent growth curve analyses using data from 372 university students (individual level) who were assigned to one of 79 e‐work groups (collective level). The participants carried out three collaborative tasks in a laboratory setting. Results reveal, at both levels, that the level of task engagement of participants and groups with high initial levels of efficacy beliefs remained stable, whereas the level of task engagement of participants and groups with low initial levels of efficacy beliefs decreased significantly over time. Moreover, the relationships linking the parallel constructs were functionally equivalent across levels. Theoretical and practical implications are discussed from the perspective of Bandura's social cognitive theory.     

Patterns of memory loss in three elderly samples

Three groups of people ranging in age from 64 to 88 years performed tasks of word generation, paired-associate recall, and free and cued recall. The groups differed in socioeconomic status, verbal intelligence, and apparent levels of daily activity. A fourth group, consisting of young undergraduates, was also tested. Results showed that whereas there were age-related differences in some tests, these age differences were strongly modulated by characteristics of the participants and characteristics of the tasks. The findings are discussed in a contextualist framework.     

Developmental and individual differences in visual memory span

The effects of chronological age (5+, 7+, 10+, and adult), articulatory suppression and spatial ability were assessed on three measures (recognition memory, partial recall, and free recall) of visual memory span for patterns, using a procedure devised by Wilson, Scott & Power (1987). Although span increased into adulthood for all three tasks, concurrent articulatory suppression acted to reduce span for the 10-year-old and adult subjects. The ability to generate accurate visuo-spatial representations at retrieval is perfectly well developed by 7 years of age. Speed of response was lengthened for the youngest age group, but was immune to the effects of concurrent articulatory suppression. Good spatial ability was associated with higher span estimates on all tasks, regardless of age. Whilst the data support the existence of a system for representing visual patterns, which increases in capacity with increasing chronological age, the system (or processes accessing it at retrieval) is not immune to verbal recoding strategies. The independent association of spatial ability with span is taken to imply that nonverbal encoding and/or maintenance strategies can act to boost visual span from at least 5 years of age.     

Word frequency and memory: effects on absolute versus relative order memory and on item memory versus order memory

Word frequency can produce opposite effects on recognition and order memory: Low-frequency words produce greater recognition accuracy, whereas high-frequency words produce superior order memory. The present experiments further delineate the relationship between word frequency and order memory. Experiment 1 indicates that low-frequency words produce worse performance on a measure of absolute order memory but not on a test of relative order, which is consistent with the idea that different forms of information underlie different types of order judgments (Greene, Thapar, & Westerman, 1998). Experiment 2 contrasted high-, low-, and very low-frequency words on recognition memory and absolute order memory. In comparison with high-frequency words, low-frequency words enhanced recognition, whereas very low-frequency words did not. Both low- and very low-frequency words, however, produced worse memory for absolute order. Thus, the relationship between frequency and item memory is an inverted U-shaped function, whereas the relationship between frequency and absolute order memory is direct. This implies that the item-enhancing effects of lower word frequency may be dissociated from its order-disrupting effects.     

Visual pattern memory requires foraging function in the central complex of Drosophila

The role of the foraging (for) gene, which encodes a cyclic guanosine-3',5'-monophosphate (cGMP)-dependent protein kinase (PKG), in food-search behavior in Drosophila has been intensively studied. However, its functions in other complex behaviors have not been well-characterized. Here, we show experimentally in Drosophila that the for gene is required in the operant visual learning paradigm. Visual pattern memory was normal in a natural variant rover (for(R)) but was impaired in another natural variant sitter (for(S)), which has a lower PKG level. Memory defects in for(S) flies could be rescued by either constitutive or adult-limited expression of for in the fan-shaped body. Interestingly, we showed that such rescue also occurred when for was expressed in the ellipsoid body. Additionally, expression of for in the fifth layer of the fan-shaped body restored sufficient memory for the pattern parameter "elevation" but not for "contour orientation," whereas expression of for in the ellipsoid body restored sufficient memory for both parameters. Our study defines a Drosophila model for further understanding the role of cGMP-PKG signaling in associative learning/memory and the neural circuit underlying this for-dependent visual pattern memory.     

Long-term semantic memory versus contextual memory in unconscious number processing

Subjects classified visible 2-digit numbers as larger or smaller than 55. Target numbers were preceded by masked 2-digit primes that were either congruent (same relation to 55) or incongruent. Experiments 1 and 2 showed prime congruency effects for stimuli never included in the set of classified visible targets, indicating subliminal priming based on long-term semantic memory. Experiments 2 and 3 went further to demonstrate paradoxical unconscious priming effects resulting from task context. For example, after repeated practice classifying 73 as larger than 55, the novel masked prime 37 paradoxically facilitated the "larger" response. In these experiments task context could induce subjects to unconsciously process only the leftmost masked prime digit, only the rightmost digit, or both independently. Across 3 experiments, subliminal priming was governed by both task context and long-term semantic memory.