Memory Decisions Research Articles

Alpha rhythm modulations in the intraparietal sulcus reflect decision signals during item recognition

Theoretical work and empirical observations suggest a contribution of regions along the intraparietal sulcus to the process of evidence accumulation during episodic memory retrieval. In the present study, we recorded magnetoencephalographic signals in a group of healthy human participants to test whether the pattern of oscillatory modulations in the lateral parietal lobe is consistent with the mnemonic accumulator hypothesis. To this aim, the dynamic properties and the spatial distribution of MEG oscillatory power modulations were investigated during an item recognition task in which the amount of evidence for old vs. new memory decisions was manipulated across three levels. A data-driven approach was employed to identify brain nodes where oscillatory activity was sensitive to both retrieval success and the amount of evidence for old decisions. The analysis identified three nodes in the left lateral parietal lobe where the event-related desynchronization (ERD) in the alpha frequency band showed both effects. Further analyses revealed that the alpha ERD in the intraparietal sulcus, but not in other parietal nodes: i. showed modulation of duration in response to the amount of evidence for both old and new decisions, ii. was behaviorally significant, and iii. more accurately tracked the subjective memory judgment rather than the objective memory status. The present findings provide support for a recent anatomical-functional model of the parietal involvement in episodic memory retrieval and suggest that the alpha ERD in the intraparietal sulcus might represent a neural signature of the evidence accumulation process during simple memory-based decisions.

Benefits and costs of predictive processing: How sentential constraint and word expectedness affect memory formation

This study investigated how the strength of schema support provided by strongly (SC) and weakly constraining (WC) sentences affects the encoding of expected and unexpected words, and how this is reflected in event-related potentials (ERPs). In a surprise recognition memory test, words studied on the previous day were presented together with new words and lures that were expected but not presented in the study phase. ERPs recorded in the study phase were compared for subsequently remembered and forgotten words. Better memory performance for expected over unexpected words was electrophysiologically supported by a parietal subsequent memory effect (SME) reflecting enhanced item-specific encoding of contextually expected words. SC sentences not only facilitated the semantic integration of sentence-ending words, as reflected in reduced N400 amplitudes, but also enabled the rapid successful encoding of these words into memory, which is evidenced by an SC > WC pattern in memory performance and correlations between pre- and post-stimulus SMEs for SC sentences. In contrast, words processed in WC sentence contexts necessitated sustained elaborative encoding processes as reflected in a late frontal slow wave SME. Expected but not presented words were associated with high rates of false positive memory decisions, indicating that these words remained in a state of high accessibility in memory even one day after the study phase. These mnemonic costs of predictive processing were more pronounced for expected words from SC sentences than from WC sentences and could reflect the lingering of strong semantic predictions which were associated with the pre-updating of sentence representations.

Episodic memory processes modulate how schema knowledge is used in spatial memory decisions

Schema knowledge can dramatically affect how we encode and retrieve memories. Current models propose that schema information is combined with episodic memory at retrieval to influence memory decisions, but it is not known how the strength or type of episodic memory (i.e., unconscious memory versus familiarity versus recollection) influences the extent to which schema information is incorporated into memory decisions. To address this question, we had participants search for target objects in semantically expected (i.e., congruent) locations or in unusual (i.e., incongruent) locations within scenes. In a subsequent test, participants indicated where in each scene the target had been located previously, then provided confidence-based recognition memory judgments that indexed recollection, familiarity strength, and unconscious memory for the scenes. In both an initial online study (n = 133) and replication (n = 59), target location recall was more accurate for targets that had been located in schema-congruent rather than incongruent locations; importantly, this effect was strongest for new scenes, decreased with unconscious memory, decreased further with familiarity strength, and was eliminated entirely for recollected scenes. Moreover, when participants recollected an incongruent scene but did not correctly remember the target location, they were still biased away from congruent regions—suggesting that detrimental schema bias was suppressed in the presence of recollection even when precise target location information was not remembered. The results indicate that episodic memory modulates how schemas are used: Schema knowledge contributes to spatial memory judgments primarily when episodic memory fails to provide precise information, and recollection can override schema bias completely.

Recognition language classifiers demonstrate far transfer of learning.

Machine learners trained on verbal justifications of recognition decisions reliably predict recognition accuracy. If these recognition language classifiers are recollection sensitive, they should generalize beyond the single-item, verbal recognition paradigms upon which they were trained. To test this, three classifiers were trained to distinguish justification language in three different single-item verbal recognition paradigms, learning to distinguish the language justifying hits from false alarms, high from medium confidence hits, and remember from know judgements. The resulting classifiers were then used to predictively score language justifying correct versus incorrect eyewitness lineup selections constituting a test of far transfer because of the differences in materials (faces vs. words), subject populations (undergraduate vs. online), testing procedures (single vs. multiple items), and test lengths (12 vs. hundreds of targets per subject) among others. All three classifiers reliably predicted eyewitness accuracy despite these differences. Additionally, mixed modeling demonstrated that the classifiers demonstrated both convergent and divergent validity with respect to the recollection sensitivity hypothesis. That is, they strongly predicted the accuracy of eyewitness selections (i.e., hits vs. false alarms) but failed to predict the accuracy of eyewitness rejections (i.e., correct rejections vs. misses). Moreover, one classifier was shown to predict eyewitness confidence despite being trained on a design devoid of all metacognitive judgments. These findings support the hypothesis that recognition language classifiers detect recollection conveyed in the language subjects use to justify their memory decisions.

On the Dynamics of a Discrete Fractional-Order Cournot–Bertrand Competition Duopoly Game

A discreet fractional-order Cournot–Bertrand competition duopoly game is introduced based on the fractional-order difference calculus of the Caputo operator. The model is designed when players can make long memory decisions. The local stability of equilibrium points is discussed for the proposed model. Some numerical simulations explore the model’s bifurcation and chaos by employing bifurcation diagrams, phase portraits, maximal Lyapunov exponents, and time series. According to our findings, the fractional-order parameter has an effect on the game’s stability and dynamics.

Risk Factors of Financial Exploitation Versus Scam

Financial exploitation (FE) perpetrators are usually seen in a position of trust, such as family members or friends, whereas perpetrators of scam tend to be unknown individuals. Few empirical studies have examined victim risk factors, and this study aimed to systematically compare risk factors of FE versus scam. One-hundred-and-ninety-five adults (ages 18-89) were recruited to complete a 60-minute survey and interview at Purdue University in Indiana (n1=97) and Scripps College in California (n2=98). Risk factors assessed included cognitive tasks (overall cognition, memory, and executive decision), socio-emotional questionnaires (depression, resilience, ostracism, and social integration), financial measures (numeracy, objective financial knowledge, retirement worries, and financial well-being), physical health and demographics (age, gender, education level, marital status, ethnicity). Additionally, participants reported experiences of FE and scam, including (1) the 11-item short-form Older Adult Financial Exploitation Measure, (2) seven questions on scam from the Health and Retirement Study, and (3) likelihood to contact a scammer after reviewing lottery scam materials. The three dependent variables were log-transformed before OLS regression models were built. Each dependent variable was associated with different risk factors. Lower standard of living (p=.02) and ostracism (p<.05) independently predicted FE. Lower physical health (b=-.02, p=.003) was the strongest predictor of scam, with lower level of financial well-being (p=.02) serving as an independent predictor. For lottery scams contact likelihood, ostracism (b=.04, p=.005) and being male (b=-.23, p=.04) were the strongest predictors. Since risk factors differed between FE and scam, prevention and intervention programs should target the unique profiles of risk factors for each.

Feeling the ease: How the use of oral motor fluency changes in amnesia.

The present study examined the evolution observed in amnesic patients' use of motor fluency when making recognition memory decisions. In this experiment, 9 patients with amnesia and 18 matched controls were presented with two recognition memory tasks composed of 3 types of items: (1) natural words, (2) nonwords difficult to pronounce, and (3) nonwords easy to pronounce, the latter having been shown to be processed in a surprisingly fluent manner as long as participants can articulate them at a subvocal level (i.e., oral motor fluency). Our results provide evidence that the motor-movement manipulation was successful to induce a fluency effect. More specifically, data revealed that both amnesic patients and control participants showed a pattern of response consistent with the use of fluency as a cue to memory for studied items. However, only control participants relied on fluency to increase their rate of "yes" responses for unstudied items. These results suggest that patients with amnesia set a more conservative response criterion before relying on oral motor fluency, showing a pattern consistent with the idea that fluency is only used as a cue to memory when it exceeds a certain threshold. These findings are discussed in terms of adaptative metacognition strategies implemented by amnesic patients to reduce fluency-based memory errors as well as in terms of the variations that seem to occur in these strategies depending on the type of fluency that is experienced.

Mixing memory and desire: How memory reactivation supports deliberative decision-making.

Memories affect nearly every aspect of our mental life. They allow us to both resolve uncertainty in the present and to construct plans for the future. Recently, renewed interest in the role memory plays in adaptive behavior has led to new theoretical advances and empirical observations. We review key findings, with particular emphasis on how the retrieval of many kinds of memories affects deliberative action selection. These results are interpreted in a sequential inference framework, in which reinstatements from memory serve as "samples" of potential action outcomes. The resulting model suggests a central role for the dynamics of memory reactivation in determining the influence of different kinds of memory in decisions. We propose that representation-specific dynamics can implement a bottom-up "product of experts" rule that integrates multiple sets of action-outcome predictions weighted based on their uncertainty. We close by reviewing related findings and identifying areas for further research. This article is categorized under: Psychology > Reasoning and Decision Making Neuroscience > Cognition Neuroscience > Computation.

Atypical meta-memory evaluation strategy in schizophrenia patients

BackgroundPrevious research has reported that patients with schizophrenia would regard false memories with higher confidence, and this meta-memory deficit was suggested as a neurocognitive marker of schizophrenia. However, how schizophrenia patients determine their memory decision confidence has received scant consideration. This study, therefore, aimed to characterize the extent to which meta-memory evaluation strategy differs between schizophrenia patients and healthy individuals, and how such difference contributes to the patients' meta-memory performance. Methods27 schizophrenia patients and 28 matched healthy controls performed a temporal-order judgement (TOJ) task, in which they judged which movie frame occurred earlier in an encoded video, and then made retrospective confidence rating. Mixed effect regression models were performed to assess the between-group metacognitive evaluation strategy difference and its relationship to clinical symptoms. ResultsCompared to the control group, the patients' confidence ratings were correlated more with the recent confidence history and less with the TOJ-related evidence. The degree of dependence on recent history of confidence was negatively correlated with the severity of positive symptoms. Furthermore, by controlling for the first-order TOJ performance, we observed that the patients discriminated correct memory decisions from the incorrect ones as accurately as the controls. ConclusionThe present investigation revealed that schizophrenia patients tend to use more heuristics in making meta-memory evaluations, and such atypical strategy is related to their clinical symptoms. This study provides new insights into how schizophrenia patients perform meta-memory processes. Future research could consider examining such metacognitive deficits in light of other cognitive domains in psychosis.

Rats use memory confidence to guide decisions

Memory enables access to past experiences to guide future behavior. Humans can determine which memories to trust (high confidence) and which to doubt (low confidence). How memory retrieval, memory confidence, and memory-guided decisions are related, however, is not understood. In particular, how confidence in memories is used in decision making is unknown. We developed a spatial memory task in which rats were incentivized to gamble their time: betting more following a correct choice yielded greater reward. Rat behavior reflected memory confidence, with higher temporal bets following correct choices. We applied machine learning to identify a memory decision variable and built a generative model of memories evolving over time that accurately predicted both choices and confidence reports. Our results reveal in rats an ability thought to exist exclusively in primates and introduce a unified model of memory dynamics, retrieval, choice, and confidence.

Distinct and common neural coding of semantic and non-semantic control demands

The flexible retrieval of knowledge is critical in everyday situations involving problem solving, reasoning and social interaction. Current theories emphasise the importance of a left-lateralised semantic control network (SCN) in supporting flexible semantic behaviour, while a bilateral multiple-demand network (MDN) is implicated in executive functions across domains. No study, however, has examined whether semantic and non-semantic demands are reflected in a common neural code within regions specifically implicated in semantic control. Using functional MRI and univariate parametric modulation analysis as well as multivariate pattern analysis, we found that semantic and non-semantic demands gave rise to both similar and distinct neural responses across control-related networks. Though activity patterns in SCN and MDN could decode the difficulty of both semantic and verbal working memory decisions, there was no shared common neural coding of cognitive demands in SCN regions. In contrast, regions in MDN showed common patterns across manipulations of semantic and working memory control demands, with successful cross-classification of difficulty across tasks. Therefore, SCN and MDN can be dissociated according to the information they maintain about cognitive demands.

The simultaneous recognition of multiple words: A process analysis

In everyday life, recognition decisions often have to be made for multiple objects simultaneously. In contrast, research on recognition memory has predominantly relied on single-item recognition paradigms. We present a first systematic investigation into the cognitive processes that differ between single-word and paired-word tests of recognition memory. In a single-word test, participants categorize previously presented words and new words as having been studied before (old) or not (new). In a paired-word test, however, the test words are randomly paired, and participants provide joint old–new categorizations of both words for each pair. Across two experiments (N = 170), we found better memory performance for words tested singly rather than in pairs and, more importantly, dependencies between the two single-word decisions implied by the paired-word test. We extended two popular model classes of single-item recognition to paired-word recognition, a discrete-state model and a continuous model. Both models attribute performance differences between single-word and paired-word recognition to differences in memory-evidence strength. Discrete-state models account for the dependencies in paired-word decisions in terms of dependencies in guessing. In contrast, continuous models map the dependencies on mnemonic (Experiment 1 & 2) as well as on decisional processes (Experiment 2). However, in both experiments, model comparison favored the discrete-state model, indicating that memory decisions for word pairs seem to be mediated by discrete states. Our work suggests that individuals tackle multiple-item recognition fundamentally differently from single-item recognition, and it provides both a behavioral and model-based paradigm for studying multiple-item recognition.

Examining the relationship between processing fluency and memory for source information.

Familiarity-based processes such as processing fluency can influence memory judgements in tests of item recognition. Many conventional accounts of source memory assume minimal influence of familiarity on source memory, but recent work has suggested that source memory judgements are affected when test stimuli are processed with greater fluency as a result of priming. The present experiments investigated the relationship between fluency and the accuracy of source memory decisions. Participants studied words presented with different source attributes. During test, they identified words that gradually clarified on screen through progressive demasking, made old/new and source memory judgements, and reported confidence ratings for those words. Response times (RTs) recorded from the item identification task formed the basis of a fluency measure, and identification RTs were compared across categories of item recognition, source accuracy and confidence. Identification RTs were faster in trials with correct retrieval of source information compared with trials for which source could not be accurately retrieved. These findings are consistent with the assumption that familiarity-based processes are related to source memory judgements.

Context Memory Encoding and Retrieval Temporal Dynamics are Modulated by Attention across the Adult Lifespan.

Episodic memories are multidimensional, including simple and complex features. How we successful encode and recover these features in time, whether these temporal dynamics are preserved across age, even under conditions of reduced memory performance, and the role of attention on these temporal dynamics is unknown. In the current study, we applied time-resolved multivariate decoding to oscillatory electroencephalography (EEG) in an adult lifespan sample to investigate the temporal order of successful encoding and recognition of simple and complex perceptual context features. At encoding, participants studied pictures of black and white objects presented with both color (low-level/simple) and scene (high-level/complex) context features and subsequently made context memory decisions for both features. Attentional demands were manipulated by having participants attend to the relationship between the object and either the color or scene while ignoring the other context feature. Consistent with hierarchical visual perception models, simple visual features (color) were successfully encoded earlier than were complex features (scenes). These features were successfully recognized in the reverse temporal order. Importantly, these temporal dynamics were both dependent on whether these context features were in the focus of one’s attention, and preserved across age, despite age-related context memory impairments. These novel results support the idea that episodic memories are encoded and retrieved successively, likely dependent on the input and output pathways of the medial temporal lobe (MTL), and attentional influences that bias activity within these pathways across age.

Mapping the time course of semantic activation in mediated false memory: Immediate classification, naming, and recognition.

We evaluated the time course of persistent automatic spreading activation from a mediated list of indirect associates (e.g., meow, day, and basement) that all converged upon a non-presented critical item (CI; e.g., black). Mediated lists were related to CIs through non-presented mediators (e.g., cat, night, and bottom). Three speeded tasks were used to evaluate the time course of semantic activation of the CI: a continuous semantic classification task (concrete/abstract decisions), a naming task (reading words aloud), or a recognition test (old/new memory decisions). Test lists were presented immediately following the mediated lists, and CIs were presented in the first, third, or eighth positions. The results revealed that in both the classification and naming tasks, CI priming was greatest in the first test position and declined across the remaining test positions. Importantly, priming was statistically reliable in the late test positions, providing evidence for long-term semantic priming (i.e., across positions on immediate tasks). False recognition, however, was stable across test positions. Collectively, these patterns suggest that spreading-activation processes decline, consistent with implicit spreading activation, and these processes may contribute to long-term false recognition.

Schematic memories develop quickly, but are not expressed unless necessary

Episodic memory retrieval is increasingly influenced by schematic information as memories mature, but it is unclear whether this is due to the slow formation of schemas over time, or the slow forgetting of the episodes. To address this, we separately probed memory for newly learned schemas as well as their influence on episodic memory decisions. In this experiment, participants encoded images from two categories, with the location of images in each category drawn from a different spatial distribution. They could thus learn schemas of category locations by encoding specific episodes. We found that images that were more consistent with these distributions were more precisely retrieved, and this schematic influence increased over time. However, memory for the schema distribution, measured using generalization to novel images, also became less precise over time. This incongruity suggests that schemas form rapidly, but their influence on episodic retrieval is dictated by the need to bolster fading memory representations.

The Language of Recollection in Support of Recognition Memory Decisions

Abstract. Researchers often augment recognition memory decisions with confidence ratings or reports of “Remember” and “Know” experiences. While important, these ratings are subject to variation in interpretation and misspecification. Here we review recent findings from a “verbal reports as data” procedure in which subjects justify, in their own words, the basis of recognition. The application of a language pattern classifier to these justifications demonstrates that it: (a) is sensitive to the presence of recollection, (b) tracks individual differences in recognition accuracy, and (c) generalizes in a theoretically meaningful way to justifications from a separate experiment. More broadly, this approach should be useful for any cognitive decision task in which competing theories suggest different explicit bases underlying the judgments, or for which the explicit versus implicit basis of the decisions is in question.

Boosting Familiarity-Based Memory Decisions in Alzheimer's Disease: The Importance of Metacognition.

Recent studies in Alzheimer's disease (AD) have suggested that AD patients are not always able to rely on their feeling of familiarity to improve their memory decisions to the same extent as healthy participants. This underuse of familiarity in AD could result from a learned reinterpretation of fluency as a poor cue for memory that would prevent them to attribute a feeling of fluency to a previous encounter. The primary goal of this study was to determine whether AD patients could relearn the association between processing fluency and past exposure after being repeatedly exposed to situations where using this association improves the accuracy of their memory decisions. Thirty-nine patients with probable AD were recruited and asked to complete several recognition tests. During these tests, participants were put either in a condition where the positive contingency between fluent processing and previous encounters with an item was systematically confirmed (intervention condition) or in a condition where there was no correlation between fluency and prior exposure (control condition). The efficacy of the intervention was evaluated at three time points (baseline, posttest, and 3-month follow-up). Our results indicated that all AD patients do not benefit to the same extent from the training. Two variables appeared to influence the likelihood that participants increase and maintain their reliance on the fluency cues after the intervention: the ability to detect the fluency manipulation and the preservation of implicit metacognitive skills. These findings indicate the importance of metacognition for inferential attribution processes in memory.

The role of anterior and medial dorsal thalamus in associative memory encoding and retrieval

A growing body of work has revealed a role for the anterior and medial dorsal thalamus in memory. Very few studies, however, have used neuroimaging to test hypotheses regarding these structures’ predicted roles in associative memory encoding and retrieval. To fill this gap, our study used fMRI in a group of healthy adults as they performed a face-scene associative memory task. We are the first to report that greater deactivation of the anterior thalamus (AT) during encoding was related to subsequent memory. This finding suggests that the AT contributes to the gating of irrelevant information during memory formation. While the medial dorsal thalamus (MD) demonstrated a positive BOLD response during the memory decision, this activity was not significantly related to the ability to correctly choose the face that “matched” the paired scene, despite this region being implicated in familiarity memory. When contrasting connectivity to the medial temporal lobe between the anterior and medial dorsal thalamic nuclei, results revealed that the medial dorsal thalamus was more strongly connected to the hippocampus, perirhinal cortex, and parahippocampal cortex. However, there was no relationship between anterior or medial dorsal thalamic functional connectivity with the MTL and memory success. These results were unexpected as extant theories of the function of the AT relate to its communication with the hippocampus and theories of the MD propose its function relates to communication with the prefrontal cortex. These findings provide novel evidence for differential roles of the anterior and medial dorsal thalamic nuclei in associative memory and inform existing models of the role of the extended hippocampal system in memory.

Too Much Familiarity! The Developmental Path of the Fluency Heuristic in Children.

We tested whether changes in attribution processes could account for the developmental differences observed in how children's use fluency to guide their memory decisions. Children ranging in age from 4 to 9years studied a list of familiar or unfamiliar cartoon characters. In Experiment 1 (n=84), participants completed a recognition test during which the perceptual fluency of some items was enhanced using a prime. In Experiment 2 (n=96), participants completed a source recollection judgment on their recognition decisions. Primed items were recognized at a higher rate than unprimed items. However, while young children rely on fluency for all items, older children use fluency only for unfamiliar items. This pattern came together with a reduction in familiarity-based-but not recollection-based-memory responses.