Psychobiological evidence for the distinction between episodic and semantic memory

The evidence for discrete neurobiological mechanisms that underlie episodic and semantic memory is reviewed. Published data from three separate lines of research are considered: studies of human amnesic patients, psychopharmacological studies of normal human subjects, and studies of working and reference memory in rodents, a distinction that is arguably analogous to the episodic/semantic dichotomy. It is concluded that the available evidence does not indicate that episodic and semantic memory are mediated by discrete neural subsystems. An alternative model of human memory is discussed, based on the concept of parallel distributed processing.An earlier version of this paper was submitted as part of the author's qualifying examination at Emory University.     

The processing of inter-item relations as a moderating factor of retrieval-induced forgetting

We investigated influences of item generation and emotional valence on retrieval-induced forgetting. Drawing on postulates of the three-factor theory of generation effects, generation tasks differentially affecting the processing of inter-item relations were applied. Whereas retrieval-induced forgetting of freely generated items was moderated by the emotional valence as well as retrieval-induced forgetting of read items, even though in the reverse direction (Experiment 1), fragment completion eliminated the moderation of retrieval-induced forgetting by emotional valence (Experiment 2). The results corroborate the assumption that the processing of inter-item relations is crucial for the immunization against retrieval-induced forgetting. Moreover, differential processing of inter-item relations may clarify the mixed results on moderating factors of retrieval-induced forgetting that have been reported.     

The very same thing: Extending the object token concept to incorporate causal constraints on individual identity

The contributions of feature recognition, object categorization, and recollection of episodic memories to the re-identification of a perceived object as the very same thing encountered in a previous perceptual episode are well understood in terms of both cognitive-behavioral phenomenology and neurofunctional implementation. Human beings do not, however, rely solely on features and context to re-identify individuals; in the presence of featural change and similarly-featured distractors, people routinely employ causal constraints to establish object identities. Based on available cognitive and neurofunctional data, the standard object-token based model of individual re-identification is extended to incorporate the construction of unobserved and hence fictive causal histories (FCHs) of observed objects by the pre-motor action planning system. It is suggested that functional deficits in the construction of FCHs are associated with clinical outcomes in both autism spectrum disorders and later-stage stage Alzheimer's disease.     

I Remember When You Taught Me That! Preschool Children's Memories of Realistic Learning Episodes

This study examined whether preschool children are able to identify the source of new knowledge that they acquired in a stimulating, interactive learning context. Sixty 4‐ to 5‐year‐old children participated in two staged learning events. Several days later, children were asked questions that assessed their knowledge of factual information presented during the events. Children indicated whether they knew the answer to each question and whether they remembered the moment they learned it (i.e. had an episodic memory of the learning event), and then recalled event details. A majority of preschoolers were able to accurately identify how they had learned at least some factual information, but this ability was not consistent across children and test items. Recall of event‐specific details was positively correlated with correct answers to factual questions. The results indicate that when preschool children are asked to reflect on past learning experiences that occurred in complex and realistic contexts, their source monitoring abilities are evident but not yet fully developed. Copyright © 2013 John Wiley & Sons, Ltd.     

Five weeks of immersive reminiscence therapy improves autobiographical memory in Alzheimer’s disease

ABSTRACT

We examined the effects of a new Immersive Reminiscence Therapy (IRT) programme on cognitive function, including autobiographical memory, in a sample Alzheimer’s disease (AD) patients. A total of 43 AD patients with mild to moderate disease severity were randomly assigned to either an intervention group (n?=?22, MMMSE?=?20.77), or a control group (n?=?21, MMMSE?=?19.24). The intervention group received one weekly group-based session of IRT for five weeks in an authentic 1950s style museum environment, matching the time of the participants’ youth. IRT included semi-structured conversations about the past. The control group received standard care. We assessed performance on cognitive function and autobiographical memory at baseline and post-intervention. Five weeks of IRT enhanced subsequent autobiographical memory performance, when participants were cued by concrete objects dated to their youth. Object-cued memories reported post intervention included a significantly higher degree of episodic details and higher word counts. The intervention showed no effect on the Autobiographical Memory Interview or word-cued recall. Global cognitive function and semantic autobiographical memory performance increased across time for both groups. Our findings demonstrate that immersion into a setting, rich on concrete cues dated to the participants’ youth can improve autobiographical remembering.     

The role of lifetime periods in the organisation of episodic memories

ABSTRACT

Research on the nature of episodic memory associations has suggested that episodic memories are associated by conceptual knowledge, where memories cluster around the same content (e.g. memories about the same people) or general-event knowledge, where memories cluster around extended events (e.g. a holiday in London), repeated events (e.g. Sunday walks in the park), or causally related events (i.e. where one event leads to another). Research has also suggested that episodic memories are associated by lifetime periods (e.g. when I was in high school), where memories cluster within lifetime periods. However, it is unclear whether episodic memories can be associated solely by lifetime periods, or if such associations are subordinate to conceptual or general-event associations. To answer this question, we reanalysed a large sample of involuntary memory chains (Mace, J. H., Clevinger, A. M., & Bernas, R. S. (2013). Involuntary memory chains: What do they tell us about autobiographical memory organisation? Memory, 21, 324–335). The results of this analysis suggested that lifetime periods associations are subordinate to conceptual and general-event associations, as lifetime periods were found to cluster within the latter two associations. The potential functions of this organisation are discussed.     

Evidence that an episodic mode of thinking facilitates encoding of perceptually rich memories for naturalistic events relative to a gist-based mode of thinking

ABSTRACT

Several studies have demonstrated that an episodic specificity induction (ESI) can influence cognitive abilities that involve episodic processes at retrieval. To better understand the downstream implications of an “episodic mode of thinking,” we investigate whether an ESI influences encoding of new events. In a between-subjects design, participants were given an ESI or gist (control) induction. In an ostensibly unrelated task, participants then were shown film clips of naturalistic events. After a filled delay, participants were given a surprise memory test, which required narrative recollection of the film clips. Participants who received the ESI generated narratives that contained more perceptual details specifically. Relative to gist thinking, an episodic mode of thinking appears to facilitate encoding of perceptually rich memories for naturalistic events.     

Remembering the past and imagining the future: Examining the consequences of mental time travel on memory

Cognitive, neuropsychological, and neuroimaging evidence suggests that remembering the past and imagining the future rely on overlapping processes in episodic memory. The three experiments reported here examine the consequences of remembering the past and imagining the future on the accessibility of other information in memory. Participants first studied events associated with a specific context and then either (a) retrieved past autobiographical events associated with that same context or (b) imagined future autobiographical events associated with that same context. Replicating and extending evidence of retrieval-induced forgetting, remembering autobiographical events from the past caused participants to forget the related studied events. However, imagining future autobiographical events failed to cause participants to forget the related studied events. These results suggest an important difference in the memorial consequences of remembering and imagining.     

The effects of emotional content on source monitoring in fibromyalgia patients

Source confusion refers to a person’s failure to distinguish whether an event has been actually seen or simply imagined. Nevertheless, prior research has demonstrated a reduction of source confusion for negative arousing information. According to the emotional-congruence effect, this emotional benefit is likely observed in patients suffering from chronic pain. This hypothesis was tested on 15 patients suffering of fibromyalgia syndrome (FMS) and 15 healthy women. In a source-monitoring task, participants had to decide whether positive, negative, and neutral words were imagined or seen with a picture. The results showed recognition deficits and more source confusion for FMS patients compared to controls. Contrary to the hypothesis of negativity bias in fibromyalgia, patients exhibited enhanced recognition for both positive and negative words. Moreover, they showed better source memory for the imagined items than for those seen with a picture. Overall, these results indicate that FMS affects episodic memory.