Deconstructing the effect of self-directed study on episodic memory

Self-directed learning is often associated with better long-term memory retention; however, the mechanisms that underlie this advantage remain poorly understood. This series of experiments was designed to “deconstruct” the notion of self-directed learning, in order to better identify the factors most responsible for these improvements to memory. In particular, we isolated the memory advantage that comes from controlling the content of study episodes from the advantage that comes from controlling the timing of those episodes. Across four experiments, self-directed learning significantly enhanced recognition memory, relative to passive observation. However, the advantage for self-directed learning was found to be present even under extremely minimal conditions of volitional control (simply pressing a button when a participant was ready to advance to the next item). Our results suggest that improvements to memory following self-directed encoding may be related to the ability to coordinate stimulus presentation with the learner’s current preparatory or attentional state, and they highlight the need to consider the range of cognitive control processes involved in and influenced by self-directed study.     

Retrieval processing and episodic memory

The emergence of brain imaging has had a major impact on research into the cognitive and neural bases of human memory. An area in which this impact has been particularly strong is retrieval processing - the processes engaged when attempting to retrieve information during a memory test. Several different classes of retrieval process - such as 'mode', 'effort' and 'success' - have been invoked to account for findings from neuroimaging studies of episodic retrieval. In this article we discuss how these different kinds of process, along with a fourth kind associated with 'retrieval orientation', can be investigated in brain imaging experiments. We then review studies of retrieval processing, and assess how well their designs match up to our proposed criteria for dissociating the neural correlates of different classes of retrieval process. We conclude that few studies have used designs that permit these different kinds of process to be independently identified, and that presently there is little evidence to indicate which kinds of processing can be fractionated in terms of their neural correlates.     

Vantage point in episodic memory

University undergraduates undertook a series of manual tasks (e.g., shaping objects out of clay) and later recalled the experiences they had while doing so from either afield or anobserver vantage point. In the former case, the subjects mentally reinstated the original task environment as if they were seeing it again through their own eyes; in the latter condition, the original task environment was envisioned from the perspective of a detached spectator. Analysis of the subjects’ recollections revealed marked differences in the contents of field and observer memories. For instance, whereas field memories afforded richer accounts of the affective reactions, physical sensations, and psychological states that the subjects experienced as they performed the tasks, observer memories included more information about how the subjects looked, what they did, or where things were. Discussion focuses on prospects for future research whose aim would be to investigate the forensic and clinical implications of the field/observer distinction.     

Retrieval-induced forgetting in episodic memory

Participants learned the locations of 12 stimuli that were uniquely colored but could be grouped by shape (4 circles, 4 triangles, 4 crosses). Following the study, a retrieval-practice phase required participants to recall the colors of a subset of the stimuli (i.e., 2 circles, 2 triangles) using shape and location as cues. In a final test, participants recalled the colors of all 12 stimuli. Compared with the control set of stimuli (i.e., 4 crosses), memory was facilitated for practiced items but impaired for related items, which were not practiced but shared the same shape group. Across experiments, retrieval-induced forgetting was observed for different perceptual groupings and for different cuing procedures. The effect, however, required retrieval of information during the interpolated phase. Providing extra presentations did not disrupt memory for related items.     

Gender differences in episodic memory

The relationship between gender and memory has been largely neglected by research, despite occasional studies reporting gender differences in episodic memory performance. The present study examined potential gender differences in episodic memory, semantic memory, primary memory, and priming. Five hundred thirty women and 470 men, randomly sampled from the city of Umeå, Sweden, 35–80 years of age, participated in the study. There were no differences between men and women with regard to age or education, or on a measure of global intellectual functioning. As has been demonstrated previously, men outperformed women on a visuospatial task and women outperformed men on tests of verbal fluency. In addition, the results demonstrated that women consistently performed at a higher level than did men on the episodic memory tasks, although there were no differences between men and women on the tasks assessing semantic memory, primary memory, or priming. The women’s higher level of performance on the episodic memory tasks could not be fully explained by their higher verbal ability.     

The role of episodic and semantic memory in episodic foresight

In this paper we describe a special form of future thinking, termed “episodic foresight” and its relation with episodic and semantic memory. We outline the methodologies that have largely been developed in the last five years to assess this capacity in young children and non-human animals. Drawing on Tulving's definition of episodic and semantic memory, we provide a critical analysis of the role that both types of memory might have on the episodic foresight tasks described in the literature. We conclude by highlighting some unanswered questions and suggesting future directions for research that could further our understanding of how memory is intimately connected to episodic foresight.     

Genetics of human episodic memory: dealing with complexity

Episodic memory is a polygenic behavioral trait with substantial heritability estimates. Despite its complexity, recent empirical evidence supports the notion that behavioral genetic studies of episodic memory might successfully identify trait-associated molecules and pathways. The development of high-throughput genotyping methods, of elaborated statistical analyses and of phenotypic assessment methods at the neural systems level will facilitate the reliable identification of novel memory-related genes. Importantly, a necessary crosstalk between behavioral genetic studies and investigation of causality by molecular genetic studies will ultimately pave the way towards the identification of biologically important, and hopefully druggable, genes and molecular pathways related to human episodic memory.     

Cognitive neuroscience of episodic memory encoding

This paper presents a cognitive neuroscientific perspective on how human episodic memories are formed. Convergent evidence from multiple brain imaging studies using positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) suggests a role for frontal cortex in episodic memory encoding. Activity levels within frontal cortex can predict episodic memory encoding across a wide range of behavioral manipulations known to influence memory performance, such as those present during levels of processing and divided attention manipulations. Activity levels within specific frontal and medial temporal regions can even predict, on an item by item basis, whether an episodic memory is likely to form. Furthermore, separate frontal regions appear to participate in supplying code-specific information, including distinct regions which process semantic attributes of verbal information as well as right-lateralized regions which process nonverbal information. We hypothesize that activity within these multiple frontal regions provides a functional influence (input) to medical temporal regions that bind the information together into a lasting episodic memory trace.     

Bio-inspired cognitive architecture of episodic memory

Memory and learning are essential functions in human beings as they allow us to acquire and store in the brain representations of thoughts, experiences, and behaviors, which are required for problem-solving in our daily life and mainly for survival. Episodic memory is a type of memory that provides the ability to re-experience events in one’s life, and it is associated with their conscious recollection. Since episodic memory can represent our experiences about the environment, similar to a mental journey, it is desired in systems that attempt to create human-like behavior. Currently, the main problem is that state of the art proposals do not consider neuroscientific evidence like memory dynamics for forgetting or bottom-up inputs, and most of them do not consider episodic memory as a different memory but as part of general declarative memory. We consider these omissions to limit the generation of human-like behavior. In this work, we propose a bio-inspired cognitive architecture of episodic memory. Neuroscientific evidence provides us with the brain structures associated with this type of memory, the connections, and the operations these areas perform. We hypothesize that virtual entities endowed with our episodic memory cognitive architecture will plan and make decisions in a more human-like fashion. To test the capabilities of the proposal, we endowed a virtual creature with a distributed and concurrent implementation of our architecture, and it was given two tasks. The first task validated the functions of the memory independently, and in the second task, the creature used episodic memory to solve a planning problem. From the results of these experiments, we validate our proposal and show that it is possible to create a system that behaves as the human brain does.     

Temporal clustering and sequencing in short-term memory and episodic memory

A model of short-term memory and episodic memory is presented, with the core assumptions that (a) people parse their continuous experience into episodic clusters and (b) items are clustered together in memory as episodes by binding information within an episode to a common temporal context. Along with the additional assumption that information within a cluster is serially ordered, the model accounts for a number of phenomena from short-term memory (with a focus on serial recall) and episodic memory (with a focus on free recall). The model also accounts for the effects of aging on serial and free recall, apparent temporal isolation effects in short- and long-term memory, and the relation between individual differences in working memory and episodic memory performance.     

Inhibition of return impairs episodic memory access

The term inhibition of return (IOR) refers to a bias against returning attention to a location or object that has recently been attended. The effect has been shown to occur in various perceptual tasks including stimulus detection, localization, and discrimination, but also to affect higher cognitive processes like lexical access. The present experiments examined whether inhibition of return would impair the high-level processing that is required in accessing item representations in episodic memory. The results show that reaction times for recognition memory decisions are increased under IOR. Furthermore, IOR affects the accuracy of recognition memory, and this effect interacts with the ease of memory access, manipulated, for example, by encoding depth in the learning phase. These results suggest that IOR impairs attentional processing up to the highest cognitive levels, including the access of prior item encounters in episodic memory.     

Disjunction and conjunction fallacies in episodic memory

It has recently been found that episodic memory displays analogues of the well-known disjunction and conjunction fallacies of probability judgement. The aim of the present research was, for the first time, to study these memory fallacies together under the same conditions, and test theoretical predictions about the reasons for each. The focus was on predictions about the influence of semantic gist, target versus context recollection, and proactive versus retroactive interference. Disjunction and conjunction fallacies increased in conditions in which subjects were able to form semantic connections among list words. In addition, disjunction fallacies were increased by manipulations that minimised proactive interference, whereas conjunction fallacies were increased by manipulations that minimised retroactive interference. That pattern suggests that disjunction fallacies are more dependent on target recollection, whereas conjunction fallacies are more dependent on context recollection.     

Inhibition of return impairs episodic memory access

The term inhibition of return (IOR) refers to a bias against returning attention to a location or object that has recently been attended. The effect has been shown to occur in various perceptual tasks including stimulus detection, localization, and discrimination, but also to affect higher cognitive processes like lexical access. The present experiments examined whether inhibition of return would impair the high-level processing that is required in accessing item representations in episodic memory. The results show that reaction times for recognition memory decisions are increased under IOR. Furthermore, IOR affects the accuracy of recognition memory, and this effect interacts with the ease of memory access, manipulated, for example, by encoding depth in the learning phase. These results suggest that IOR impairs attentional processing up to the highest cognitive levels, including the access of prior item encounters in episodic memory.     

Parietal lobe contributions to episodic memory retrieval

Although the parietal lobe is not traditionally thought to support declarative memory, recent event-related fMRI studies of episodic retrieval have consistently revealed a range of memory-related influences on activation in lateral posterior parietal cortex (PPC) and precuneus extending into posterior cingulate and retrosplenial cortex. This article surveys the fMRI literature on PPC activation during remembering, a literature that complements earlier electroencephalography data. We consider these recent memory-related fMRI responses within the context of classical ideas about parietal function that emphasize space-based attention and motor intention. We conclude by proposing three hypotheses concerning how parietal cortex might contribute to memory.     

情景记忆成功年老化的神经机制

随着年龄的增长,大部分老年人的情景记忆会出现衰退,但也会有一部分老年人的情景记忆表现出成功的年老化,即记忆成绩较好或随增龄的衰退程度较小。脑保持理论、神经去分化理论、认知储备理论以及神经补偿理论分别从不同角度解释了情景记忆成功年老化的神经机制。基于选择性优化与补偿模型对现有理论进行整合,发现情景记忆成功年老化可能与个体的认知储备水平直接相关：高认知储备的老年人能够对情景记忆相关的脑区和脑网络进行优化且具备更强的神经补偿能力,因而其脑功能(比如,神经表征和神经加工通路的特异性)可能会保持地更好。未来研究需要更多地采用纵向设计来考察各理论之间的关系及其影响因素,从而更好地解释记忆成功年老化的神经机制并为提升老年人的脑与认知健康提供支持。     

Egocentric-updating during navigation facilitates episodic memory retrieval

Influential models suggest that spatial processing is essential for episodic memory [O’Keefe, J., & Nadel, L. (1978). The hippocampus as a cognitive map. London: Oxford University Press]. However, although several types of spatial relations exist, such as allocentric (i.e. object-to-object relations), egocentric (i.e. static object-to-self relations) or egocentric updated on navigation information (i.e. self-to-environment relations in a dynamic way), usually only allocentric representations are described as potentially subserving episodic memory [Nadel, L., & Moscovitch, M. (1998). Hippocampal contributions to cortical plasticity. Neuropharmacology, 37(4-5), 431-439]. This study proposes to confront the allocentric representation hypothesis with an egocentric updated with self-motion representation hypothesis. In the present study, we explored retrieval performance in relation to these two types of spatial processing levels during learning. Episodic remembering has been assessed through Remember responses in a recall and in a recognition task, combined with a “Remember-Know-Guess” paradigm [Gardiner, J. M. (2001). Episodic memory and autonoetic consciousness: A first-person approach. Philosophical Transactions of the Royal Society B: Biological Sciences, 356(1413), 1351-1361] to assess the autonoetic level of responses. Our results show that retrieval performance was significantly higher when encoding was performed in the egocentric-updated condition. Although egocentric updated with self-motion and allocentric representations are not mutually exclusive, these results suggest that egocentric updating processing facilitates remember responses more than allocentric processing. The results are discussed according to Burgess and colleagues’ model of episodic memory [Burgess, N., Becker, S., King, J. A., & O’Keefe, J. (2001). Memory for events and their spatial context: models and experiments. Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences, 356(1413), 1493-1503].     

Units of episodic memory in perceptual recognition

Two studies examined the cognitive units of sentence memory using a perceptual recognition task. Four candidate cognitive units were considered: concepts, propositions, integrated propositions, and nonintegrated propositions. Subjects first received a list of acquisition sentences and then were asked to reproduce sentences presented under a white-noise mask. These masked sentences were replicas of the acquisition sentences, were formed of recombined clauses from the acquisition sentences, or were formed of recombined words from the acquisition sentences. Reproduction accuracy was employed as the dependent measure. Results supported propositions (operationalized by clauses) as cognitive units of episodic memory. No conclusive evidence was obtained for concepts, integrated propositions, or nonintegrated propositions as cognitive units. The utility of perceptual recognition tasks for studying the cognitive units of episodic memory is discussed.     

Sex differences in the correlation of memory span with scan and other episodic memory tasks

Three studies of the relationship between memory span and other measures of memory and information processing are reported here. These other measures included memory scanning rate, the short- and long-term components of free recall, and word recognition from long-term memory. All three studies produced evidence for a sex difference in the correlation of these tasks with memory span. The first study produced a partial replication of Chiang and Atkinson's report (Memory & Cognition, 1976, 4,661–667) of a sex difference: for males, span and scanning rate were unrelated, while for females they were positively correlated. The second study showed that span and the primary memory component of free recall had a modest positive correlation for females but not for males, while span was unrelated to measures of secondary or long-term memory for females but was consistently positively related for males. In the third study, recognition accuracy and span were uncorrelated for females, but positively correlated for males. Finally, a reanalysis of data from a large-scale study by Underwood, Baruch, and Malmi (Journal of Experimental Psychology: General, 1978, 107, 393–419) also showed evidence of similar sex differences. Sex differences involving the correlation of memory span with other cognitive test performances seem quite general and need to be taken account of in the analyses of individual differences in memory and cognitive processes. A tentative theory is presented to account for the differences found in these studies.