Benefits and Costs of Context Reinstatement in Episodic Memory: An ERP Study

The effects of episodic context on memory integration

Information encountered in different events, such as people and objects, can be interlinked in memory. Such memory integration supports novel inferences about the world. This study investigates the role of episodic context on memory integration in two experiments using an associative inference task. Participants encoded events with overlapping (AB and BC) and non-overlapping associations (XY) presented in the same or different episodic contexts. Inference performance across events (AC) was tested in the absence (Experiment 1) and in the presence (Experiment 2) of the encoding context. Our data show that inferences across events encoded in the same context were more accurate, faster, and made with greater confidence compared to those encoded in different contexts. However, this effect was observed only when the context was presented during testing, suggesting that context enhances associative inferences by facilitating retrieval of events associated with that context. These findings demonstrate that revisiting the encoding context promotes memory integration by providing privileged access to contextually associated memory traces and facilitating their flexible recombination to form novel inferences.

Ingroup sources enhance associative inference

Episodic memory encompasses flexible processes that enable us to create and update knowledge by making novel inferences across overlapping but distinct events. Here we examined whether an ingroup source enhances the capacity to draw such inferences. In three studies with US-American samples (NStudy1 = 53, NStudy2 = 68, NStudy3 = 68), we investigated the ability to make indirect associations, inferable from overlapping events, presented by ingroup or outgroup sources. Participants were better at making inferences based on events presented by ingroup compared to outgroup sources (Studies 1 and 3). When the sources did not form a team, the effect was not replicated (Study 2). Furthermore, we show that this ingroup advantage may be linked to differing source monitoring resources allocated to ingroup and outgroup sources. Altogether, our findings demonstrate that inferential processes are facilitated for ingroup information, potentially contributing to spreading biased information from ingroup sources into expanding knowledge networks, ultimately maintaining and strengthening polarized beliefs.

Electrophysiological evidence for context reinstatement effects on object recognition memory

Reinstating the context present at encoding during the test phase generally enhances recognition memory compared with changing the context when specific item-context associations are established during encoding. However, it remains unclear whether context reinstatement improves the performance in differentiating between old and similar items in recognition memory tests and what underlying cognitive processes are involved. Using the context reinstatement paradigm together with event-related potentials (ERP), we examined the context-dependent effects of background scenes on recognition discrimination among similar objects. Participants were instructed to associate intentionally specific objects with background scenes during the encoding phase and subsequently complete an object recognition memory task, during which old and similar new objects were presented superimposed over the studied old or similar new background scenes. Electroencephalogram was recorded to measure the electrophysiological manifestations of cognitive processes associated with episodic retrieval. Behavioral results revealed enhanced performance in differentiating old from similar objects in the old context, as opposed to the similar context condition. Importantly, ERP results indicated a more pronounced recollection-related parietal object old/new effect in the old context compared to the similar context condition. This suggests that the ability to distinguish between old and similar objects in recognition memory is primarily driven by recollection rather than familiarity, particularly when the encoding context is reinstated during the test phase. Our findings are in line with the account that the impact of context reinstatement on object recognition memory is attributable to the enhanced recollection of specific item-context associations during retrieval and provides evidence for the specificity of episodic associative representations.

Encoding contexts are incidentally reinstated during competitive retrieval and track the temporal dynamics of memory interference

The ability to remember an episode from our past is often hindered by competition from similar events. For example, if we want to remember the article a colleague recommended during the last lab meeting, we may need to resolve interference from other article recommendations from the same colleague. This study investigates if the contextual features specifying the encoding episodes are incidentally reinstated during competitive memory retrieval. Competition between memories was created through the AB/AC interference paradigm. Individual word-pairs were presented embedded in a slowly drifting real-word-like context. Multivariate pattern analysis (MVPA) of high temporal-resolution electroencephalographic (EEG) data was used to investigate context reactivation during memory retrieval. Behaviorally, we observed proactive (but not retroactive) interference; that is, performance for AC competitive retrieval was worse compared with a control DE noncompetitive retrieval, whereas AB retrieval did not suffer from competition. Neurally, proactive interference was accompanied by an early reinstatement of the competitor context and interference resolution was associated with the ensuing reinstatement of the target context. Together, these findings provide novel evidence showing that the encoding contexts of competing discrete events are incidentally reinstated during competitive retrieval and that such reinstatement tracks retrieval competition and subsequent interference resolution.

Temporal Dynamics of Memory-guided Cognitive Control and Generalization of Control via Overlapping Associative Memories

Goal-directed behavior can benefit from proactive adjustments of cognitive control that occur in anticipation of forthcoming cognitive control demands (CCD). Predictions of forthcoming CCD are thought to depend on learning and memory in two ways: First, through direct experience, associative encoding may link previously experienced CCD to its triggering item, such that subsequent encounters with the item serve to cue retrieval of (i.e., predict) the associated CCD. Second, in the absence of direct experience, pattern completion and mnemonic integration mechanisms may allow CCD to be generalized from its associated item to other items related in memory. While extant behavioral evidence documents both types of CCD prediction, the neurocognitive mechanisms giving rise to these predictions remain largely unexplored. Here, we tested two hypotheses: (1) memory-guided predictions about CCD precede control adjustments due to the actual CCD required; and (2) generalization of CCD can be accomplished through integration mechanisms that link partially overlapping CCD-item and item-item associations in memory. Supporting these hypotheses, the temporal dynamics of theta and alpha power in human electroencephalography data (n = 43, 26 females) revealed that an associative CCD effect emerges earlier than interaction effects involving actual CCD. Furthermore, generalization of CCD from one item (X) to another item (Y) was predicted by a decrease in alpha power following the presentation of the X-Y pair. These findings advance understanding of the mechanisms underlying memory-guided adjustments of cognitive control.SIGNIFICANCE STATEMENT Cognitive control adaptively regulates information processing to align with task goals. Experience-based expectations enable adjustments of control, leading to improved performance when expectations match the actual control demand required. Using EEG, we demonstrate that memory for past cognitive control demand proactively guides the allocation of cognitive control, preceding adjustments of control triggered by the demands of the present environment. Furthermore, we demonstrate that learned cognitive control demands can be generalized through mnemonic integration processes, enabling the spread of expectations about cognitive control demands to items associated in memory. We reveal that this generalization is linked to decreased alpha oscillation in medial frontal channels. Collectively, these findings provide new insights into how memory-control interactions facilitate goal-directed behavior.

Neural Pattern Classification Tracks Transfer-Appropriate Processing in Episodic Memory

The transfer-appropriate processing (TAP) account holds that episodic memory depends on the overlap between encoding and retrieval processing. In the current study, we employed multivariate pattern analysis (MVPA) of electroencephalography to examine the relevance of spontaneously engaged visual processing during encoding for later retrieval. Human participants encoded word-picture associations, where the picture could be a famous face, a landmark, or an object. At test, we manipulated the retrieval demands by asking participants to retrieve either visual or verbal information about the pictures. MVPA revealed classification between picture categories during early perceptual stages of encoding (∼170 ms). Importantly, these visual category-specific neural patterns were predictive of later episodic remembering, but the direction of the relationship was contingent on the particular retrieval demand of the memory task: a benefit for the visual and a cost for the verbal. A reinstatement of the category-specific neural patterns established during encoding was observed during retrieval, and again the relationship with behavior varied with retrieval demands. Reactivation of visual representations during retrieval was associated with better memory in the visual task, but with lower performance in the verbal task. Our findings support and extend the TAP account by demonstrating that processing of particular aspects during memory formation can also have detrimental effects on later episodic remembering when other aspects of the event are called-for and shed new light on encoding and retrieval interactions in episodic memory.