Declarative working memory: A bio-inspired cognitive architecture proposal

Memory is considered one of the most important functions since it allows us to code, store and retrieve knowledge. These qualities make it an indispensable function for a virtual creature. In general, memory can be classified based on the durability of the stored data in working memory and long-term memory. Working memory refers to the capacity to maintain temporarily a limited amount of information in mind, which can then be used to support various abilities, including learning, reasoning, planning and decision-making. Unlike short-term memory, working memory is not only a storage site, but it is also a framework of interacting processes that involve the temporary storage and manipulation of information in the service of performing complex cognitive activities. Declarative memory is a type of long-term memory related with the storage of facts and events. This research focuses on the development of a cognitive architecture for the type of working memory that maintains and manipulates declarative information. The construction of the model was grounded in theoretical evidence taken from cognitive sciences such as neuroscience and psychology, which gave us the components and their processes. The model was evaluated through a case study that covers the encoding, storing, and retrieval stages. Our hypothesis is that a virtual creature endowed with our working memory model will provide faster access to the information needed for the ongoing task. Therefore, it improves the planning and decision-making processes.     

Bio-inspired cognitive model of motor learning by imitation

Learning, and even more so by imitation, is an essential Cognitive Functions because it is carried out throughout life and allows us to adapt our behaviors from other beings through observation. In this work, we propose a model, and implementation of the cognitive function of imitation motor learning (IML), based on psychological and neuroscientific evidence. According to the evidence, learning by imitation includes imitation of action and imitation of action over an object sub-processes. The imitation of action consists of the movement of the limbs. The imitation of action over an object consists of the interaction with an object within the environment. We achieve an implementation of the proposed model for IML and endow a virtual entity with it. In order to validate the proposal, we use a case study to analyze the sub-processes performance. From results, we conclude that both imitation of action and imitation of action over an object sub-processes play an essential role in getting the agent to interact with stimuli within the environment.     

Memory systems within a cognitive architecture

This article addresses the division of memory systems in relation to an overall cognitive architecture. As understanding the architecture is essential to understanding the mind, developing computational cognitive architectures is an important enterprise in computational psychology (computational cognitive modeling). The article proposes a set of hypotheses concerning memory systems from the standpoint of a cognitive architecture, in particular, the four-way division of memory (including explicit and implicit procedural memory and explicit and implicit declarative memory). It then discusses in detail how these hypotheses may be validated through examining qualitatively the literature on memory. A quick review follows of computational simulations of a variety of quantitative data (which are not limited to narrowly conceived “memory tasks”). Results of accounting for both qualitative and quantitative data point to the promise of this approach.     

Narrative organisation at encoding facilitated children's long-term episodic memory

This study examined the effect of narrative organisation at encoding on long-term episodic memory in a sample of five- to seven-year-old children (N = 113). At an initial interview, children were asked to narrate a story from a picture book. Six months later, they were interviewed again and asked to recall the story and answer a series of direct questions about the story. Children who initially encoded more information in narrative and produced more complete, complex, cohesive and coherent narratives remembered the story in greater detail and accuracy following the six-month interval, independent of age and verbal skills. The relation between narrative organisation and memory was consistent across culture and gender. These findings provide new insight into the critical role of narrative in episodic memory.     

The effects of sleep on episodic memory in older and younger adults

Evidence on sleep-dependent benefits for episodic memory remains elusive. Furthermore we know little about age-related changes on the effects of sleep on episodic memory. The study we report is the first to compare the effects of sleep on episodic memories in younger and older adults. Memories of stories and personal events were assessed following a retention interval that included sleep and following an equal duration of wakefulness. Both older and younger adults have superior memory following sleep compared to following wakefulness for both types of material. Amount of forgetting of personal events was less during wakefulness in older adults than in younger adults, possibly due to spontaneous rehearsal. Amount of time spent sleeping correlated highly with sleep benefit in older adults, suggesting that quantity of total sleep, and/or time spent in some stages of sleep, are important contributors to age-related differences in memory consolidation or protection from interference during sleep.     

The influence of action on episodic memory: A virtual reality study

A range of empirical findings suggest that active learning is important for memory. However, few studies have focused on the mechanisms underlying this enactment effect in episodic memory using complex environments. Research using virtual reality has yielded inconsistent results. We postulated that the effect of action depends on the degree of interaction with the environment and freedom in the planning of an itinerary. To test these hypotheses, we disentangled the interaction and planning components of action to investigate whether each enhances factual and spatial memory. Seventy-two participants (36 male and 36 female) explored a virtual town in one of three experimental conditions: (a) a passive condition where participants were immersed as passenger of the car (no interaction, no planning); (b) a planning-only condition (the subject chose the itinerary but did not drive the car); (c) an interaction-only condition (the subject drove the car but the itinerary was fixed). We found that itinerary choice and motor control both enhanced spatial memory, while factual memory was impaired by online motor control. The role of action in memory is discussed.     

Single-trial learning of "what" and "who" information in a gorilla (Gorilla gorilla gorilla): implications for episodic memory

Single-trial learning and long-term memory of "what" and "who" information were examined in an adult gorilla (Gorilla gorilla gorilla). We presented the gorilla with a to-be-remembered food item at the time of study. In Experiment 1, following a retention interval of either approximately 7 min or 24 h, the gorilla responded with one of five cards, each corresponding to a particular food. The gorilla was accurate on 70% of the short retention-interval trials and on 82% of the long retention-interval trials. In Experiment 2, the food stimulus was provided by one of two experimenters, each of whom was represented by a card. The gorilla identified the food (55% of the time) and the experimenter (82% of the time) on the short retention-interval trials. On the long retention-interval trials, the gorilla was accurate for the food (73%) and for the person (87%). The results are interpreted in light of theories of episodic memory. Electronic Publication     

Neural substrates for episodic encoding and recognition of unfamiliar faces

Functional MRI was used to investigate brain activation in healthy volunteers during encoding of unfamiliar faces as well as during correct recognition of newly learned faces (CR) compared to correct identification of distractor faces (CF), missed alarms (not recognizing previously presented faces, MA), and false alarms (incorrectly recognizing newly presented faces, FA). Encoding was associated with frontal, occipital/fusiform, thalamic, and cerebellar activation. CR produced activation in frontal and cerebellar regions, whereas CF activated frontal and occipitotemporal regions as well as the thalamus. In contrast, MA was associated with frontal and thalamic activation, and FA with frontal activation. The CR minus CF comparison showed left lateral prefrontal and parietal activation, while no suprathreshold positive signal changes were detected when subtracting the other conditions (CR minus MA, CR minus FA, and vice versa). These results support the view that the successful episodic retrieval of newly learned faces is based on a dorsal visual stream mechanism.     

The opportunity to choose enhances long-term episodic memory

ABSTRACT

Episodic memory is typically studied under conditions that treat participants as passive agents. Here we sought to explore how actively engaging in ongoing naturalistic occurrences affects long-term episodic memory. Participants viewed 40 short movie clips that depicted a protagonist that conversed with the participants. In each clip, they were either offered the chance to (supposedly) determine the clip’s continuation (active condition), or let the computer decide for them (passive condition). Participants returned either two days or one week after the experience to undergo a true/false memory test for the clips’ details and a two-alternative recognition test for the choices made. Memory performance for both groups was superior for information and choices conveyed in the active vs. passive condition. These findings suggest that the sense of actively influencing the unfolding of events is beneficial to long-term memory of the experience at large, baring potential interventions in the fields of education and cognitive enhancement.     

The relationship between prospective memory and episodic future thinking in younger and older adulthood

Episodic future thinking (EFT), the ability to project into the future to “preexperience” an event, and prospective memory (PM), remembering to perform an intended action, are both examples of future-oriented cognition. Recently it has been suggested that EFT might contribute to PM performance but to date few studies have examined the relationship between these two capacities. The aim of the present study was to investigate the nature and specificity of this relationship, as well as whether it varies with age. Participants were 125 younger and 125 older adults who completed measures of EFT and PM. Significant, positive correlations between EFT and PM were identified in both age groups. Furthermore, EFT ability accounted for significant unique variance in the young adults, suggesting that it may make a specific contribution to PM function. Within the older adult group, EFT did not uniquely contribute to PM, possibly indicating a reduced capacity to utilize EFT, or the use of compensatory strategies. This study is the first to provide systematic evidence for an association between variation in EFT and PM abilities in both younger and older adulthood and shows that the nature of this association varies as a function of age.     

Higher body mass index is associated with episodic memory deficits in young adults

Obesity has become an international health crisis. There is accumulating evidence that excess bodyweight is associated with changes to the structure and function of the brain and with a number of cognitive deficits. In particular, research suggests that obesity is associated with hippocampal and frontal lobe dysfunction, which would be predicted to impact memory. However, evidence for such memory impairment is currently limited. We hypothesised that higher body mass index (BMI) would be associated with reduced performance on a test of episodic memory that assesses not only content, but also context and feature integration. A total of 50 participants aged 18–35 years, with BMIs ranging from 18 to 51, were tested on a novel what–where–when style episodic memory test: the “Treasure-Hunt Task”. This test requires recollection of object, location, and temporal order information within the same paradigm, as well as testing the ability to integrate these features into a single event recollection. Higher BMI was associated with significantly lower performance on the what–where–when (WWW) memory task and all individual elements: object identification, location memory, and temporal order memory. After controlling for age, sex, and years in education, the effect of BMI on the individual what, where, and when tasks remained, while the WWW dropped below significance. This finding of episodic memory deficits in obesity is of concern given the emerging evidence for a role for episodic cognition in appetite regulation.     

Episodic memory and episodic foresight in 3- and 5-year-old children

In the present study, we examined the development of episodic memory and episodic foresight. Three- and 5-year-olds were interviewed individually using a personalised timeline that included photographs of them at different points in their life. After constructing the timeline with the experimenter, each child was asked to discuss a number of different events: an event that happened yesterday, an event that happened earlier today, an event that would happen later today, and an event that would happen tomorrow. As judged by their parents, children's accounts were highly accurate. After controlling for age and language scores, there was a strong relation between amount of information reported about past and future events. Overall, 5-year-olds reported more total information than 3-year-olds; however, reports by 3-year-olds included a similar proportion of first-person reference as did reports by 5-year-olds. No age difference appeared in proportion of future-oriented talk. We conclude that the present task provides a promising method of exploring the emergence of mental time travel during early childhood.     

Mixed-handedness advantages in episodic memory obtained under conditions of intentional learning extend to incidental learning

The existence of handedness differences in the retrieval of episodic memories is well-documented, but virtually all have been obtained under conditions of intentional learning. Two experiments are reported that extend the presence of such handedness differences to memory retrieval under conditions of incidental learning. Experiment 1 used Craik and Tulving’s (1975) classic levels-of-processing paradigm and obtained handedness differences under incidental and intentional conditions of deep processing, but not under conditions of shallow incidental processing. Experiment 2 looked at incidental memory for distracter items from a recognition memory task and again found a mixed-handed advantage. Results are discussed in terms of the relation between interhemispheric interaction, levels of processing, and episodic memory retrieval.     

The effects of an acute psychosocial stressor on episodic memory

Although stressors are believed to impair memory, experimental studies with humans have provided inconsistent support for this conclusion. The current study was designed to examine the effect of an acute psychosocial stressor, and subsequent reactivity, on episodic memory. One hundred participants completed a list-recall task before and after random assignment into a stressor or nonstressor condition. Participants assigned to the stressor condition exhibited both impaired delayed and immediate recall, and also exhibited increasesin the commission of intrusions and perseverations. The experience of off-task thoughts and intentional suppression of such thoughts, were associated with greater impairment of immediate recall. Changes in state anxiety, negative mood, and heart rate were unrelated to changes in memory. These data indicate that exposure to a stressor impaired the recall of previously learned information, and compromised the recall of newly acquired information. Furthermore, cognitive interference is an important factor regarding stress-related impairments of episodic memory.     

Temporal compression in episodic memory for real-life events

Remembering an event typically takes less time than experiencing it, suggesting that episodic memory represents past experience in a temporally compressed way. Little is known, however, about how the continuous flow of real-life events is summarised in memory. Here we investigated the nature and determinants of temporal compression by directly comparing memory contents with the objective timing of events as measured by a wearable camera. We found that episodic memories consist of a succession of moments of prior experience that represent events with varying compression rates, such that the density of retrieved information is modulated by goal processing and perceptual changes. Furthermore, the results showed that temporal compression rates remain relatively stable over one week and increase after a one-month delay, particularly for goal-related events. These data shed new light on temporal compression in episodic memory and suggest that compression rates are adaptively modulated to maintain current goal-relevant information.     

Similarity and attraction effects in episodic memory judgments

In the decision-making literature, it is known that preferences between two options can be influenced in different ways by the introduction of a third option. We investigated whether such influences could be demonstrated when making decisions about qualitative aspects of episodic memories. In a baseline condition, participants were asked which of two dissimilar events they remembered more vividly: (A) a well-known Olympic victory, or (B) the death of a well-known public figure. In two further conditions, a third event was added: (C) an Olympic victory similar and competitive to A, or (D) an Olympic victory similar but inferior to A. With the addition of C, participants were less likely to choose A than B (similarity effect), whereas with the addition of D, they were more likely to choose A than B (attraction effect), suggesting that effects known in decision-making can be generalised to relative judgments about episodic memories.     

The effects of gender on the retrieval of episodic and semantic components of autobiographical memory

Despite consistent evidence that women exhibit greater episodic memory specificity than men, little attention has been paid to gender differences in the production of episodic details during autobiographical recall under conditions of high and low retrieval support. Similarly the role of gender on the production of semantic details used to support autobiographical memory recollections of specific events has been largely unexplored. In the present study an undergraduate sample of 50 men and 50 women were assessed using the Autobiographical Interview (Levine, Svoboda, Hay, Winocur, & Moscovitch, 2002). Women recalled more episodic information compared to men in the high retrieval support condition, whereas no gender differences were found in the low retrieval support condition. In addition, women produced more repetitions compared to men in the high retrieval support condition. No gender differences were found in the production of semantic details. These results are interpreted in terms of gender differences in encoding and reminiscence practices. This research adds to the literature on gender differences in memory recall and suggests that gender is an important variable in explaining individual differences in AM recall.     

The influence of episodic memory decline on value-based choice

Recent studies suggest the involvement of episodic memory in value-based decisions as a source of information about subjective values of choice options. We therefore tested the link between age-related memory decline and inconsistencies in value-based decisions in 30 cognitively healthy older adults. Within the pre-registered experiment, the inconsistencies were measured in two ways: i) the consistency between stated preferences and revealed choices; ii) the amount of intransitivities in choice triplets, revealed in a forced paired choice task including all possible pairings of 20 food products. Although no significant association of memory functions to number of intransitive triplets was observed, participants with lower memory scores were more likely to choose the item for which they stated a lower preference. The results suggest a higher noise in the underlying preference signal in participants with lower memory. We discuss the results in the context of the unique needs of elderly consumers.     

Emotional intensity in episodic autobiographical memory and counterfactual thinking

Episodic counterfactual thoughts—imagined alternative ways in which personal past events might have occurred—are frequently accompanied by intense emotions. Here, participants recollected positive and negative autobiographical memories and then generated better and worse episodic counterfactual events from those memories. Our results suggest that the projected emotional intensity during the simulated remembered/imagined event is significantly higher than but typically positively related to the emotional intensity while remembering/imagining the event. Furthermore, repeatedly simulating counterfactual events heightened the emotional intensity felt while simulating the counterfactual event. Finally, for both the emotional intensity accompanying the experience of remembering/imagining and the projected emotional intensity during the simulated remembered/imagined event, the emotional intensity of negative memories was greater than the emotional intensity of upward counterfactuals generated from them but lower than the emotional intensity of downward counterfactuals generated from them. These findings are discussed in relation to clinical work and functional theories of counterfactual thinking.