Theories Of Episodic Memory Research Articles

Referntial Activity as a Measure of Episodic Memory.

A computerized measure of Referential Activity (RA), the High WRAD Proportion (HWP), which assesses the proportion of high RA language in a text, was compared to a widely used measure of episodic memory, the proportion of internal details (IP), those pertaining directly to the main event being described. Both measures, along with several additional computerized measures, were applied to narratives of past and future events, produced by two groups of speakers varying in age. The HWP and IP showed correlations with high effect sizes for all age groups and narrative time periods, providing strong validation for the RA concept and for HWP as a computerized measure of episodic memory. Differences were also found between the results for both narrative time and participant age based on the two measures. HWP scores for narratives of past experience were higher than for future narratives; these differences were supported by other computerized measures applied to the narratives. The differences were in the same direction but were not significant for IP. Older participants showed significantly lower levels of episodic memory, according to IP; the differences were in the same direction but were not significant for HWP. The implications of these results for the RA concept and for the multiple code theory of episodic memory are discussed.

The spatiotemporal organization of episodic memory and its disruption in a neurodevelopmental disorder

Recent theories of episodic memory (EM) posit that the hippocampus provides a spatiotemporal framework necessary for representing events. If such theories hold true, then does the development of EM in children depend on the ability to first bind spatial and temporal information? And does this ability rely, at least in part, on normal hippocampal function? We investigated the development of EM in children 2–8 years of age (Study 1) and its impairment in Williams Syndrome, a genetic neurodevelopmental disorder characterized by visuospatial deficits and irregular hippocampal function, (Study 2) by implementing a nonverbal object-placement task that dissociates the what, where, and when components of EM. Consistent with the spatiotemporal-framework view of hippocampal EM, our results indicate that the binding of where and when in memory emerges earliest in development, around the age of 3, and is specifically impaired in WS. Space-time binding both preceded and was critical to full EM (what + where + when), and the successful association of objects to spatial locations seemed to mediate this developmental process.

Activation of stimulus-specific processing regions at retrieval tracks the strength of relational memory.

Many theories of episodic memory posit that the subjective experience of recollection may be driven by the activation of stimulus-specific cortical regions during memory retrieval. This study examined cortical activation during associative memory retrieval to identify brain regions that support confidence judgments of source memory in stimulus-specific ways. Adjectives were encoded with either a picture of a face or a scene. During a source memory test, the word was presented alone and the participant was asked if the word had been previously paired with a face or a scene. We identified brain regions that were selectively active when viewing pictures of scenes or faces with a separate localizer scan. We then identified brain regions that were differentially activated to words during the source memory test that had been previously paired with faces or scenes, masked by the localizer activations, and examined how those regions were modulated by the strength of the source memory. Bilateral amygdala activation tracked source memory confidence for faces, while parahippocampal cortex tracked source memory confidence for scenes. The magnitude of the activation of these domain-specific perceptual-processing brain regions during memory retrieval may contribute to the subjective strength of episodic recollection.

The list strength effect in cued recall

Abstract Episodic memory is the process by which information about experienced events is encoded and retrieved. Successful retrieval of episodic memories is dependent on the way in which memory is tested and as a result many effects and theories of episodic memory are task dependent. One such finding is the list strength effect. In free recall, a positive list strength effect is observed; memory for a given item is harmed by the presence of other strongly encoded items and helped by the presence of other weakly encoded items. In recognition, a null list strength is observed; memory for a given item is unaffected by the strength of other items. Such differential empirical findings are crucial to understanding memory, but it is undesirable to have multiple task-specific theories rather than a unified theory of memory. Here we use cued recall, a task that shares properties of both free recall and recognition, to move toward that goal. In a series of 5 experiments, we observed a null list strength effect in cued recall. We suggest that a successful theory would entail the use of both item and context information during retrieval, consistent with the approach of the Search of Associative Memory model.

An Emotional Mediation Theory of Differential Age Effects in Episodic and Semantic Memories

ABSTRACT Although there is a large decrement in central episodic memory processes as adults age, there is no appreciable decrement in central semantic memory processes (Allen et al., Journal of Gerontology: Psychological Sciences, 57B, P173–P186, 2002; Allen et al., Experimental Aging Research, 28, 111–142, 2002; Mitchell, Journal of Experimental Psychology: Learning, Memory, and Cognition, 15, 31–49, 1989). The authors develop a theory of episodic memory's connections to cognitive, emotional, and motivational systems to explain these differential age effects. The theory is discussed within the context of the cognitive neuroscience research regarding limbic system connectivity in conjunction with Damasio's notion of somatic markers (Descartes’ error: Emotion, reason, and the human brain, New York: Grosset/Putnam, 1994). The central hypothesis is that elements of limbic system circuitry, including portions of the medial temporal lobes and frontal cortex, are associated with both working and long-term episodic memory performance, and by extension, with the capacity to engage in emotion-guided, self-regulatory processes that depend heavily on episodic memory. In contrast, the semantic memory system may have less shared interface with episodic and affective networks (i.e., the limbic-related system), and therefore remain independent of neurocognitive changes impacting emotional states and episodic-type memory processes. Accordingly, this framework may account for the pattern of age-related declines in episodic relative to semantic memory, particularly if older adults experience less emotional activation, and therefore fewer somatic markers, than younger adults. An initial empirical examination of this emotional mediation theory is presented, using preexisting data that include indicators of age, chronic tendency to focus on negative emotional stimuli (neuroticism), and working memory performance.

Imaging Episodic Memory: Implications for Cognitive Theories and Phenomena

Functional neuroimaging studies are beginning to identify neuroanatomical correlates of various cognitive functions. This paper presents results relevant to several theories and phenomena of episodic memory, including component processes of episodic retrieval, encoding specificity, inhibition, item versus source memory, encoding-retrieval overlap, and the picture-superiority effect. Overall, by revealing specific activation patterns, the results provide support for existing theoretical views and they add some unique information which may be important to consider in future attempts to develop cognitive theories of episodic memory.

MRI of mental time travel

The experience of remembering past events carries with it such an intense sensation of past experience that it has been called ‘mental time travel’1xToward a theory of episodic memory: the frontal lobes and autonoetic consciousness. Wheeler, M.A. et al. Psychol. Bull. 1997; 121: 331–354Crossref | PubMedSee all

The Role of Episodic Memory in Learning from University Lectures

We tested three hypotheses concerning the mediational effects of students′ memories and their preferences for imaginal or verbal processing on their retention of declarative and episodic information from regularly scheduled university lectures. Results supported a prediction from Paivio′s (1986) dual coding theory that imaginal elaborations during lectures assist students′ recall of both episodic and declarative information, but did not support a prediction based on Tulving′s (1983) theory of episodic memory that episodic memories of the lectures would mediate retention of declarative information conveyed in the lectures. The data were also interpreted to suggest that students with preferences for imaginal processing might retain more episodic detail from lectures.

The Effects of Different Types of Encoding Task on Memory for Famous Faces and Names

In this study, incidental memory for familiar faces following different types of encoding task was investigated. Subjects who had been asked to name faces of celebrities at presentation subsequently remembered them significantly better than subjects who had been asked to provide contextual information about the faces, and than subjects who had been asked to distinguish them from unfamiliar faces. This effect persisted regardless of whether the tests required memory for names, faces, or biographical information. It is argued that these results can be explained in terms of the face-processing framework of Bruce and Young (1986) and the theory of episodic memory for faces put forward by Bruce (1982, 1988). However the findings are not consistent with levels of processing (Craik & Lockhart, 1972), nor transfer appropriate processing (Morris, Bransford, & Franks, 1977).