Electrophysiological Correlates of Familiarity and Recollection in Associative Recognition: Contributions of Perceptual and Conceptual Processing to Unitization

Changes in the level of unitization moderate the impact of unitization on associative memory and its underlying processing

The viewpoint that unitization provides a possibility of increasing the contribution of familiarity to associative memory has been widely accepted, but its effects on associative memory and recollection remain controversial. The current study aims to explain these mixed results by considering a potential moderator: changes in the level of unitization from encoding to retrieval phases. During the encoding phase, participants learned the related and unrelated picture pairs (i.e., high vs. low levels of unitization). Subsequently, they needed to distinguish between the intact and rearranged pairs during retrieval, where, in these rearranged pairs, the level of unitization from encoding to retrieval phases may or may not change. Meanwhile, the scalp electroencephalographic activity (EEG) was recorded. The results showed a significant familiarity-related FN400 old/new effect for related picture pairs alone, which supported the above viewpoint. However, its impact on the associative memory and recollection-related LPC old/new effects varied with the level of unitization changes-specifically, under the unchanged conditions. Although related pairs elicited significant FN400 and LPC old/new effects, the differences in these old/new effects and associative memory between the related and unrelated picture pairs were not significant. Conversely, under the changed conditions, related picture pairs not only elicited significantly larger FN400 and LPC old/new effects but also improved associative memory more than unrelated picture pairs. These findings not only clarify some of the inconsistencies in the literature concerning the impact of unitization on associative memory but also suggest that unitization affects the contributions of familiarity and recollection to associative memory differently, its effectiveness varying with the level of unitization changes.

Improving memory through choice and deliberation in decision-making: Evidence from ERPs

The goal of decision-making is to select one option and disregard the others. However, deliberation can also create a memory association between the chosen and unchosen options. This study aims to investigate how choice and deliberation affect the memory of postdecision options and the underlying mechanisms. Using event-related potentials (ERPs), we examined item recognition (Experiment 1) and associative recognition (Experiment 2) following certain and uncertain decisions. In Experiment 1, items that were chosen in certain decisions were remembered better than unchosen items. There was no difference between chosen and unchosen items in uncertain decisions. Moreover, a late recollection-related LPC (a late positive component) old/new effect was larger for chosen items than unchosen items in certain decisions. The early familiarity-related FN400 and the late recollection-related LPC old/new effects were significant for chosen and unchosen items in uncertain decisions. In Experiment 2, there was no difference in performance on associative memory. A FN400 old/new effect (an index of integration) in certain or uncertain decisions was not observed. Although significant LPC old/new effects were found in both certain and uncertain decisions, no difference was found between them. These results propose that decision-making can enhance item memory performance through two distinct processes: value and elaboration. Elaboration involves focusing on the details within items rather than integrating items into a cohesive whole.

Improving associative memory in younger and older adults with unitization: evidence from meta-analysis and behavioral studies

Introduction

The finding that familiarity can support associative memory by unitizing the to -be-learned items into a novel representation has been widely accepted, but its effects on overall performance of associative memory and recollection are still controversial.

Methods

The current study aims to elucidate these discrepancies by identifying potential moderating factors through a combined approach of meta-analysis and behavioral experiment.

Results

Results consistently showed that changes in the level of unitization and age groups were two important moderators. Specifically, unitization enhanced younger and older adults' associative memory and its supporting processes (i.e., familiarity and recollection) when the level of unitization between studied and rearranged pairs was changed. However, when this level remained constant, unitization exhibited no impact on associative memory and familiarity in younger adults, but showed an enhanced effect in older adults. Furthermore, results revealed a marked group difference between younger and older adults in associative memory when the unitization level of noncompound words remained unaltered. Upon breaking this condition, the group difference was reduced by enhancing familiarity or recollection.

Discussion

These findings not only clarify some of the inconsistencies in the literature concerning the impact of unitization on associative memory, but also suggest that unitization is a beneficial strategy for reducing group difference in associative memory, with its effectiveness varying according to the level of unitization changes.

The effect of part-list cuing on associative recognition

The modulation of part-list cuing on item memory has been well-documented, whereas its impact on associative memory remains largely unknown. The present study explored the effect of part-list cuing on associative recognition and, more specifically, whether this forgetting effect caused by part-list cuing is more sensitive to recollection or familiarity in recognition memory. Experiments 1a and 1b combined the intact/rearranged/new judgement task of associative recognition with the classical part-list cuing paradigm, and the result showed that part-list cuing impaired the recognition accuracy of "intact" and "rearranged" face-scene pairs. Moreover, the discriminability score of relational recognition and item recognition was significantly decreased in the part-list cuing condition compared to the no-part-list cuing condition. Experiments 2a and 2b further used the Remember/Know/Guess task to explore which recognition processes (recollection vs. familiarity) were sensitive to the presentation of part-list cuing. The results showed that part-list cuing reduced the familiarity of relational recognition and the recollection and familiarity of item recognition. These findings suggest that part-list cuing was harmful to the recognition of relationships (familiarity) and items (recollection and familiarity) in associative memory.

The beneficial effects of concept definition and interactive imagery tasks on associative memory: Evidence from event-related potentials

It is widely accepted that familiarity can support associative memory when the to-be-remember items are unitized into a new representation. However, there has been relatively little attention devoted to investigating the effects of different unitization manipulations on associative memory. The present study aimed to address this gap by examining the effects of varying levels of unitization through three tasks: Concept definition, interactive imagery, and sentence frame tasks. The behavioral results revealed that associative memory was significantly enhanced in the interactive imagery task compared to the sentence frame task. However, no significant differences were found between the sentence frame and concept definition tasks, or between the concept definition and interactive imagery tasks. In terms of the neural correlates, the event-related potential (ERP) results revealed that the sentence frame task only elicited a significant recollection-related LPC old/new effect, while the concept definition task only elicited a significant familiarity-related FN400 old/new effect. However, the interactive representation task elicited both of these distinct effects. These findings suggest that both the concept definition and interactive imagery tasks can enhance familiarity for supporting associative memory, but their beneficial effects on associative memory or LPC old/new effects may be different.

Comparing two unitisation manipulations: effects on familiarity, recollection-based recognition, and semantic interference

The recognition of associative memory can be significantly influenced by the use of an encoding strategy known as unitisation, which has been implemented through various manipulations. However, [Shao, H., Opitz, B., Yang, J., & Weng, X. (2016). Recollection reduces unitised familiarity effect. Memory (Hove, England), 24(4), 535-547. https://doi.org/10.1080/09658211.2015.1021258] found intriguing distinctions between two common manipulations, the compound task and the imagery task, leading to a dispute. We propose that differences in levels of processing in the imagery task may account for these discrepancies. This study tested our hypothesis using two approaches. The first two experiments utilised the R/K paradigm to investigate the effects of these methods on familiarity-based and recollection-based recognition. The results demonstrated that familiarity was increased in the compound task, while recollection was increased in the imagery task. In the subsequent two experiments, an interference paradigm was employed to examine differences in semantic processing within the two tasks. The results showed that the compound task did not impact participants' inclination towards lures, while the imagery task led to a bias towards semantic lures over episodic lures, suggesting that the two encodings in the imagery task involve different levels of semantic processing. These results support our hypothesis and underscore the importance of carefully choosing comparisons that account for other variables in the study of unitisation.

A meta-analysis of event-related potential correlates of recognition memory

A longstanding question in memory research is whether recognition is supported by more than one mnemonic process. Dual-process models distinguish recollection of episodic detail from familiarity, while single-process models explain recognition in terms of one process that varies in strength. Dual process models have drawn support from findings that recollection and familiarity elicit distinct electroencephalographic event-related potentials (ERPs): a mid-frontal ERP effect that occurs at around 300-500 ms post-stimulus onset and is often larger for familiarity than recollection contrasts, and a parietal ERP effect that occurs at around 500-800 ms and is larger for recollection than familiarity contrasts. We sought to adjudicate between dual- and single-process models by investigating whether the dissociation between these two ERP effects is reliable over studies. We extracted effect sizes from 41 experiments that had used Remember-Know, source memory, and associative memory paradigms (1,000 participants). Meta-analysis revealed a strong interaction between ERP effect and mnemonic process of the form predicted by dual-process models. Although neither ERP effect was significantly process-selective taken alone, a moderator analysis revealed a larger mid-frontal effect for familiarity than recollection contrasts in studies using the Remember-Know paradigm. Mega-analysis of raw data from six studies further showed significant process-selectivity for both mid-frontal and parietal ERPs in the predicted time windows. On balance, the findings favor dual- over single-process theories of recognition memory, but point to a need to promote sharing of raw data.

From encoding to retrieval: Change in level of unitization resolves debate about Unitization's effect on associative recognition

Although it is widely accepted that familiarity could support associative recognition when the to-be-learn items are 'unitized' into a new representation, the effects of unitization on associative recognition and recollection remain much debated. The current study aimed to explain these debates by exploring when and how unitization benefits associative recognition using event-related potentials (ERPs). During the encoding phase, participants learned compound words and unrelated word pairs (i.e., High vs. Low level of unitization). At retrieval, the compound words were rearranged into new compound words (i.e., no-change) and unrelated word pairs (i.e., change). Similarly, the unrelated word pairs were rearranged into new unrelated word pairs (i.e., no-change) and compound words (i.e., change). Results showed that under the no-change condition, unitization did not affect associative recognition, nor its underlying processes. In contrast, under the change condition, unitization improved associative recognition by increasing both familiarity-related FN400 effect and recollection-related LPC effect. In addition, a planned comparison between the compound-change and unrelated-no change conditions-a common index for unitization effect in past studies-revealed that unitization could not only elicit significant FN400 effect, but also improve associative recognition by increasing LPC effect. Collectively, these results not only allowed to explain the current discrepancies in the literature concerning the effect of unitization on associative recognition, but also emphasized the importance of matching the level of unitization between the studied and rearranged word pairs.

Effects of emotion and semantic relatedness on recognition memory: Behavioral and electrophysiological evidence

Some aspects of our memory are enhanced by emotion, whereas others can be unaffected or even hindered. Previous studies reported impaired associative memory of emotional content, an effect termed associative "emotional interference". The current study used EEG and an associative recognition paradigm to investigate the cognitive and neural mechanisms associated with this effect. In two experiments, participants studied negative and neutral stimulus-pairs that were either semantically related or unrelated. In Experiment 1 emotions were relevant to the encoding task (valence judgment) whereas in Experiment 2 emotions were irrelevant (familiarity judgment). In a subsequent associative recognition test, EEG was recorded while participants discriminated between intact, rearranged, and new pairs. An associative emotional interference effect was observed in both experiments, but was attenuated for semantically related pairs in Experiment 1, where valence was relevant to the task. Moreover, a modulation of an early associative memory ERP component (300-550 ms) occurred for negative pairs when valence was task-relevant (Experiment 1), but for semantically related pairs when valence was irrelevant (Experiment 2). A later ERP component (550-800 ms) showed a more general pattern, and was observed in all experimental conditions. These results suggest that both valence and semantic relations can act as an organizing principle that promotes associative binding. Their ability to contribute to successful retrieval depends on specific task demands.

Recallable but not recognizable: The influence of semantic priming in recall paradigms

When people can successfully recall a studied word, they should be able to recognize it as having been studied. In cued-recall paradigms, however, participants sometimes correctly recall words in the presence of strong semantic cues but then fail to recognize those words as actually having been studied. Although the conditions necessary to produce this unusual effect are known, the underlying neural correlates have not been investigated. Across five experiments, involving both behavioral and electrophysiological methods (EEG), we investigated the cognitive and neural processes that underlie recognition failures. Experiments 1 and 2 showed behaviorally that assuming that recalled items can be recognized in cued-recall paradigms is a flawed assumption, because recognition failures occur in the presence of cues, regardless of whether those failures are measured. With event-related potentials (ERPs), Experiments 3 and 4 revealed that successfully recalled words that are recognized are driven by recollection at recall and then by a combination of recollection and familiarity at ensuing recognition. In contrast, recognition failures did not show that memory signature and may instead be driven by semantic priming at recall and followed at recognition stages by negative-going ERP effects consistent with implicit processes, such as repetition fluency. These results demonstrate that recall - long-characterized as predominantly reflecting recollection-based processing in episodic memory - may at times also be served by a confluence of implicit cognitive processes.

The different effects of concept definition and interactive imagery encoding on associative recognition for word and picture stimuli

Traditional view holds that associative recognition require recollection while familiarity can't support associative recognition. However, recent research indicate that familiarity can also contribute to associative recognition when the stimuli are unitized in encoding. Here, we investigated the electrophysiological correlates of retrieval of word and picture stimuli in three encoding conditions. Semantically unrelated word pairs or picture pairs were encoded in concept definition, interactive imagery, and item comparison conditions, separately. In test, the participants were required to discriminate between old pairs that appeared in the same pairing as in study, rearranged pairs that appeared in different pairings in study, or completely new pairs. The behavioral results revealed that higher associative recognition was observed in interactive imagery condition than in concept definition condition, with item comparison condition eliciting the worst recognition, regardless of word or picture stimuli. ERP results of word stimuli revealed that the FN400 old/new effect was solely elicited in concept definition and interactive imagery conditions, but not in item comparison condition. However, ERP results of picture stimuli revealed that the late FN400 old/new effect was observed in three encoding conditions and that larger magnitude of old/new effect was elicited in item comparison condition than in interactive imagery condition. There may be different neural mechanisms of unitization on associative recognition for word and picture stimuli. These findings suggested that the pattern of engagement of familiarity during successful retrieval was dependent on the stimulating properties and the encoding conditions. We will discuss the possibility that top-down unitization which manipulates two unrelated stimuli through instructions may lead to the engagement of specific forms of familiarity-association familiarity and item familiarity.

Part-List Cues Hinder Familiarity but Not Recollection in Item Recognition: Behavioral and Event-Related Potential Evidence

Participants' memory performance is normally poorer when a subset of previously learned items is provided as retrieval cues than none of the retrieval cues is provided. This phenomenon is called the part-list cuing effect, which has been discovered in numerous behavioral studies. However, there is currently no relevant behavioral or event-related potential (ERP) research to investigate whether the forgetting effect caused by part-list cues is more sensitive to recollection or to familiarity. By combining the part-list cuing paradigm with the Remember/Know procedure, we investigated this issue in the present ERP study. Behavioral data showed part-list cuing induced detrimental effect in two aspects: significantly lowered familiarity of the target items and decreased memory discrimination score (P_r score) for "Know" but not for "Remember" items in the part-list cue condition than in the no-part-list cue condition. ERP data revealed that the FN400 old/new effects, which are associated with familiarity, were absent when providing part-list cues, whereas the late positive complex (LPC) old/new effects, which are associated with recollection, were observed comparably in both part-list cue and no-part-list cue conditions. Converging behavioral and ERP results suggested that part-list cues hindered familiarity-based retrieval but not recollection-based retrieval of item recognition. Theoretical implications of the findings for the part-list cuing effect are discussed.

The role of cognitive reserve in the relationship between metabolic syndrome and cognitive functioning

Metabolic syndrome (MetS) is a cluster of vascular risk factors that can impact cognition. Cognitive reserve (CR), specifically early operators of reserve (e.g., education), have not been explored in the relationship between MetS and cognition. Adults 45-90 years old (n = 149) underwent neuropsychological testing and evaluation for MetS. Exploratory and confirmatory factor analyses defined neuropsychological domains and created a CR score based on early operators of CR. Regression analyses examined the association among MetS, CR, and neuropsychological performance. CFA revealed two neuropsychological factors: Episodic Memory and Executive Functioning. Controlling for age and physical ability, MetS and CR were significant predictors of the Factors. With CR in the model, MetS became a non-significant predictor of Executive Functioning; CR and physical ability were the most significant predictors. CR and MetS significantly predicted Episodic Memory . The results are discussed in the context of neuroprotective factors and cognitive aging.

Under the condition of unitization at encoding rather than unitization at retrieval, familiarity could support associative recognition and the relationship between unitization and recollection was moderated by unitization-congruence

It is widely accepted that associative recognition can be supported by familiarity through integrating more than two stimuli into a unit, but there are still three unsolved questions: (1) how unitization affects recollection-based associative recognition; (2) whether it is necessary to match the level of unitization (LOU) between original and rearranged pairs, which was term as unitization-congruence (UC); (3) whether unitization can occur at encoding or at retrieval. The purposes of this study are to try to answer these questions. During the encoding phase, the participants were asked to learn compound words and unrelated word pairs, and during the retrieval phase, they needed to distinguish intact pairs from rearranged consistent and rearranged inconsistent pairs with "remember/know" paradigm. The results showed that (1) the role of unitization in recollection was moderated by UC; (2) Under the consistent UC condition, unitization could improve familiarity-based associative recognition without affecting recollection-based associative recognition, while under the inconsistent UC condition, unitization could improve familiarity-based and recollection-based associative recognition simultaneously, these results indicated that it was necessary to match the LOU between original and rearranged pairs; (3) unitization at encoding could support familiarity-based associative recognition, while unitization at retrieval did not. In briefly, unitization at encoding could improve associative recognition and this effect was moderated by UC, while unitization at retrieval did not affect associative recognition.

Unitization modulates recognition of within-domain and cross-domain associations: Evidence from event-related potentials

Although it is often assumed that memory of episodic associations requires recollection, it has been suggested that, when stimuli are experienced as a unit, earlier memory processes might contribute to their subsequent associative recognition. We investigated the effects of associative relations and perceptual domain during episodic encoding on the ability to utilize early memory processes to retrieve associative information. During the study phase, participants encoded compound and noncompound words pairs, presented either to the same sensory modality (visual presentation) or to different sensory modalities (audiovisual presentation). At the test phase, they discriminated between old, rearranged, and new pairs while ERPs were recorded. In an early ERP component, differences related to associative memory emerged only for compounds, regardless of their encoding modality. These findings indicate that episodic retrieval of compound words can be supported by early-onset recognition processes regardless of whether both words were presented to the same or different sensory modalities, and suggests that unitization can operate at an abstract level, across a broad range of materials.

How do word frequency and memory task influence directed forgetting: An ERP study

In daily life, it is important either to remember sometimes or to intentionally forget on other occasions. The issue of forgetting following instructions (i.e. directed forgetting, DF) has been broadly studied; however, whether the frequency of contents would matter in DF remains unclear, and the understanding of its neural mechanism in both circumstances of item memory and source memory requires improvement in depth. For these purposes, the current study manipulated word frequency and memory task to investigate relevant behavioral features and neural activities of DF. Adopting event-related potential (ERP) technique, this study applied two-character Chinese words of two types of word frequency (high vs low) in the item-method DF paradigm. During encoding, we found that the increased frontal positivity, an index of active inhibition, was regulated by both word frequency and memory task, while the enhanced parietal positivity reflecting selective rehearsal didn't fluctuate across conditions. In the course of test, three ERP old/new effects were identified: the familiarity-based FN400 and the recollection-driven LPC were both modulated by word frequency and memory task, but the right frontal old/new effect was significant solely in source memory; also, these effects provided compelling evidence for the influences of word frequency and memory task on DF. Our results reinforce the differentiation between absolute familiarity and relative familiarity in memory, reveal their sensitivity to DF, and also support the dual-process interpretation. Implications are made to examine more influential factors for future research.

Dissociating neural correlates of retrieval practice and elaborative study in associative recognition memory

Retrieval practice effect refers to better long-term retention enhanced by active retrieval compared to re-studying, which has been widely demonstrated. However, controversies remain as to whether the underlying mechanism of this effect could be attributed to semantic elaboration. We investigated whether retrieval practice and elaboration were equivalent by observing the underlying cognitive processes of the two conditions using corresponding event-related potentials measures of associative memory and item memory. Behavioral results showed that retrieval practice induced better associate memory performance than elaborative study. For event-related potential results, an early old/recombined effect (FN400) related to familiarity and a late old/recombined effect (late positive component) related to recollection emerged in the retrieval practice condition, while both were absent in the elaborative study condition. An early recombined/new effect (FN400) appeared in the elaborative study condition, which did not occur in the retrieval practice condition. It could be inferred that retrieval practice promoted the recollection of episodic contexts for later associative memory, while elaborative study strengthened the familiarity of individual item. These findings suggest that retrieval practice and elaboration are two distinctive processes.

Episodic memory and executive functions in cognitively healthy individuals display distinct neuroanatomical correlates which are differentially modulated by aging

The neuroanatomical bases of episodic memory (EM) and executive functions (EFs) have been widely addressed in patients with brain damage and in individuals with neurologic disorders. These studies reported that larger brain structures support better outcomes in both cognitive domains, thereby supporting the “bigger is better” account. However, relatively few studies have explored the cerebral morphological properties underlying EM and EFs in cognitively healthy individuals and current findings indicate no unitary theoretical explanation for the structure–function relationship. Moreover, existing studies have typically restricted the analyses to a priori defined regions of interest. Here we conducted unbiased voxel‐wise analysis of the associations between regional gray as well as white matter volumes (GMv; WMv) and performance in both cognitive domains in a sample of 463 cognitively intact individuals. We found that efficiency in EM was predicted by lower GMv in brain areas belonging to the default‐mode network (DMN). By contrast, EFs performance was predicted by larger GMv in a distributed set of regions, which overlapped with the executive control network (ECN). Volume of white matter bundles supporting both cross‐cortical and interhemispheric connections was positively related to processing speed. Furthermore, aging modulated the relationship between regional volumes and cognitive performance in several areas including the hippocampus and frontal cortex. Our data extend the critical role of the DMN and ECN by showing that variability in their morphological properties, and not only their activation patterns, affects EM and EFs, respectively. Moreover, our finding that aging reverts these associations supports previously advanced theories of cognitive neurodevelopment.