Specificity of episodic and semantic aspects of autobiographical memory in relation to symptoms of posttraumatic stress disorder (PTSD)

Two studies examined the relationship between the ability to access specific autobiographical material in memory and presence/symptoms of posttraumatic stress. In Study 1, a sample of refugees with a diagnosis of posttraumatic stress disorder (PTSD) completed the Autobiographical Memory Test (AMT) in which they had to generate specific episodic autobiographical memories in response to emotion-related cue words. Results showed that reduced specificity of memories on the AMT was associated with an increased frequency of trauma-related flashbacks but with reduced use of effortful avoidance to deal with trauma-related intrusions in the day-to-day. Study 2 examined retrieval of semantic autobiographical information from previous lifetime periods in groups of cancer survivors with posttraumatic stress and healthy controls. The cancer survivors were able to generate fewer specific semantic details about the personal past compared to the controls. The more symptomatic survivors showed the greatest memory impairment. The data from both studies are discussed in terms of compromised access to specific autobiographical material in distressed trauma survivors reflecting a process of affect regulation.     

Overgeneral autobiographical memory recollection in Iranian combat veterans with posttraumatic stress disorder

This study examined the recollection of autobiographical material in memory among Iranian military veterans with and without posttraumatic stress disorder (PTSD), and healthy non-trauma-exposed control subjects. Participants completed the Autobiographical Memory Test, Autobiographical Memory Interview (counterbalanced), Impact of Event Scale-Revised, Beck Depression Inventory-II, Wechsler Memory Scale-III and Wechsler Adult Intelligence Scale-Revised. The PTSD group generated fewer specific episodic and semantic details of autobiographical memory compared to the non-PTSD and control groups. Working memory did not significantly moderate the relationship between PTSD diagnosis and reduced autobiographical memory specificity but did moderate the relationship between PTSD diagnosis and semantic recall; semantic memory recall was not significantly related to working memory ability for those with PTSD but was related to working memory ability for trauma survivors without PTSD. While the data provide some support for the expectation that higher working memory ability is associated with an increased ability to retrieve specific memories (i.e. semantic memory recall in those without PTSD), the findings are also consistent with the view that for those with PTSD the demands on working memory required for affect regulation cancel out this influence of working memory in augmenting access to specific memories.     

More emotional facial expressions during episodic than during semantic autobiographical retrieval

There is a substantial body of research on the relationship between emotion and autobiographical memory. Using facial analysis software, our study addressed this relationship by investigating basic emotional facial expressions that may be detected during autobiographical recall. Participants were asked to retrieve 3 autobiographical memories, each of which was triggered by one of the following cue words: happy, sad, and city. The autobiographical recall was analyzed by a software for facial analysis that detects and classifies basic emotional expressions. Analyses showed that emotional cues triggered the corresponding basic facial expressions (i.e., happy facial expression for memories cued by happy). Furthermore, we dissociated episodic and semantic retrieval, observing more emotional facial expressions during episodic than during semantic retrieval, regardless of the emotional valence of cues. Our study provides insight into facial expressions that are associated with emotional autobiographical memory. It also highlights an ecological tool to reveal physiological changes that are associated with emotion and memory.     

The slave model of autobiographical memory

In this paper the nature of the relationship between psychological mechanisms that process semantic information and those that process autobiographical memory is considered. On the basis of theoretical work by Endel Tulving, and empirical research into the construction of false memories, a novel model of autobiographical memory construction is proposed. This model is referred to as the slave model of autobiographical memory and has that the mechanisms responsible for the production of autobiographical memories are enslaved to those that support semantic information, in the sense that beliefs determine the content of autobiographical memory. Implications of the model for the potential double dissociation of semantic and episodic memory are considered; as are recent accounts of autobiographical memory construction.     

'I remember therefore I am, and I am therefore I remember': exploring the contributions of episodic and semantic self-knowledge to strength of identity

The present research explores the relationship between the two components of autobiographical memory--episodic and semantic self-knowledge--and identity strength in older adults living in the community and residential care. Participants (N= 32) completed the autobiographical memory interview and measures of personal identity strength and multiple group memberships. Contrary to previous research, autobiographical memory for all time periods (childhood, early adulthood, and recent life) in the semantic domain was associated with greater strength in personal identity. Further, we obtained support for the hypothesis that the relationship between episodic self-knowledge and identity strength would be mediated by knowledge of personal semantic facts. However, there was also support for a reverse mediation model indicating that a strong sense of identity is associated with semantic self-knowledge and through this may enhance self-relevant recollection. The discussion elaborates on these findings and we propose a self-knowledge and identity model (SKIM) whereby semantic self-knowledge mediates a bidirectional relationship between episodic self-knowledge and identity.     

Directed forgetting of autobiographical memory in mild Alzheimer's disease

Using the autobiographical directed forgetting method (Barnier et al., 2007), the present paper addressed the intentional inhibitory processes of episodic and semantic autobiographical memory in Alzheimer's disease (AD). Mild AD patients and healthy elderly people were instructed to either forget or to continue remembering previously generated autobiographical events. In a later recall test they were asked to reconstruct the early-generated memories regardless of the forget/remember instruction. Autobiographical reconstruction was further distributed into episodic and semantic memories. Results showed no forget instruction effect on episodic or semantic autobiographical recall with AD patients, whereas healthy elderly people were able to inhibit only episodic autobiographical memories. The findings suggest an impairment of the intentional inhibitory processes in autobiographical memory with AD and a relative preservation of these mechanisms with normal ageing. They also demonstrate an earlier decline in the intentional inhibitory processes compared to the autobiographical deterioration in AD.     

Directed forgetting of autobiographical memory in mild Alzheimer's disease

Using the autobiographical directed forgetting method (Barnier et al., 2007), the present paper addressed the intentional inhibitory processes of episodic and semantic autobiographical memory in Alzheimer's disease (AD). Mild AD patients and healthy elderly people were instructed to either forget or to continue remembering previously generated autobiographical events. In a later recall test they were asked to reconstruct the early-generated memories regardless of the forget/remember instruction. Autobiographical reconstruction was further distributed into episodic and semantic memories. Results showed no forget instruction effect on episodic or semantic autobiographical recall with AD patients, whereas healthy elderly people were able to inhibit only episodic autobiographical memories. The findings suggest an impairment of the intentional inhibitory processes in autobiographical memory with AD and a relative preservation of these mechanisms with normal ageing. They also demonstrate an earlier decline in the intentional inhibitory processes compared to the autobiographical deterioration in AD.     

Autobiographical memory and well-being in aging: The central role of semantic self-images

Higher levels of well-being are associated with longer life expectancies and better physical health. Previous studies suggest that processes involving the self and autobiographical memory are related to well-being, yet these relationships are poorly understood. The present study tested 32 older and 32 younger adults using scales measuring well-being and the affective valence of two types of autobiographical memory: episodic autobiographical memories and semantic self-images. Results showed that valence of semantic self-images, but not episodic autobiographical memories, was highly correlated with well-being, particularly in older adults. In contrast, well-being in older adults was unrelated to performance across a range of standardised memory tasks. These results highlight the role of semantic self-images in well-being, and have implications for the development of therapeutic interventions for well-being in aging.     

Ageing and autobiographical memory for emotional and neutral events

We investigated age-related effects in recall of emotional and neutral autobiographical memories. Protocols were scored according to episodic and non-episodic detail categories using the Autobiographical Interview. Young adults recalled a greater number of episodic details compared to older adults, whereas older adults recalled more semantic details, replicating previous findings. Both young and older adults' emotional memories contained more overall detail than neutral ones, with the enhancement from emotion-specific to episodic details, but this did not alter the effect of age group on the pattern of episodic and semantic details. However, the age effect on episodic details was attenuated for neutral autobiographical memories. The findings suggest that age differences for emotional autobiographical recollection might reflect a more general pattern of age-related changes in memory, with impaired recall of episodic components and relative sparing of semantic aspects of autobiographical memory in older adults when compared to young adults.     

The effect of burn injury on adolescents autobiographical memory

Autobiographical memory recall was investigated in two female adolescent groups; one group who had experienced a burn injury and a matched control group. The Burn group was not currently depressed or anxious, but scored significantly higher on the intrusion subscale of the impact of event scale compared to controls. Two autobiographical memory tasks, the autobiographical memory cueing task and the Children's Autobiographical Memory Inventory (CAMI), were used. For the cueing task, the Burn group was significantly slower to recall specific memories. This group also recalled significantly fewer specific memories and significantly more extended overgeneral memories. For the CAMI, the burns group produced significantly lower semantic and episodic recall. The Burn group also produced significant correlations between sub-scales of the impact of event scale and selected measures on the autobiographical memory tasks. Higher intrusion scores were associated with less detailed episodic recall. Higher avoidance scores were associated with longer latencies to recall memories to negative cue words and fewer specific memories to all cue words. These results are discussed from the perspective that the Burn group experienced intrusive thoughts which interfered with normal autobiographical functioning.     

Altering access to autobiographical episodes with prior semantic knowledge

Within autobiographical knowledge, semantic and episodic memory are traditionally considered separate, but newer models place them along a continuum, which raises the possibility of an intermediate form of knowledge - personal semantics. This study tested how different types of semantics – general semantics and two forms of personal semantics – impact access to personal episodic memories. In two experiments, participants made a series of true/false judgments about a prime statement, which reflected a general semantic fact, a context-dependent (e.g., repeated event) or context-independent (e.g., trait), personal semantic fact and then retrieved a specific past episodic memory. There was a significantly stronger priming effect for accessing specific episodic memories after judging personal semantic facts versus general facts. We also found that context-dependent and -independent personal semantic facts had separable priming effects on episodic memory. These findings support a continuum model of memory and verifies that there are multiple forms of personal knowledge.     

Simulating episodic memory deficits in semantic dementia with the TraceLink model

Although semantic dementia is primarily characterised by deficits in semantic memory, episodic memory is also impaired. Patients show poor recall of old autobiographical and semantic memories, with better retrieval of recent experiences; they can form new memories, and normal performance on pictorial recognition memory has been demonstrated. As these abnormalities in episodic memory are virtually a mirror image of those seen in the amnesic syndromes, semantic dementia poses a challenge to extant models of remote memory and amnesia. Here, we show that one such model, TraceLink, can reproduce some of the principal findings on episodic memory in semantic dementia. A loss of nodes and connections within the trace system, which can be identified with the temporal neocortical memory storage sites implicated in semantic dementia, simulates without further assumptions the findings reported above.     

Simulating episodic memory deficits in semantic dementia with the TraceLink model

Although semantic dementia is primarily characterised by deficits in semantic memory, episodic memory is also impaired. Patients show poor recall of old autobiographical and semantic memories, with better retrieval of recent experiences; they can form new memories, and normal performance on pictorial recognition memory has been demonstrated. As these abnormalities in episodic memory are virtually a mirror image of those seen in the amnesic syndromes, semantic dementia poses a challenge to extant models of remote memory and amnesia. Here, we show that one such model, TraceLink, can reproduce some of the principal findings on episodic memory in semantic dementia. A loss of nodes and connections within the trace system, which can be identified with the temporal neocortical memory storage sites implicated in semantic dementia, simulates without further assumptions the findings reported above.     

Episodic and semantic contributions to older adults' autobiographical recall

The authors examined episodic and semantic contributions to 2 salient features of older adults' autobiographical recall: the reminiscence bump and the retention effect. Forty well-educated and healthy older men (mean age = 72.5 years; SD = 1.1) recalled personal memories in response to a series of cue words. They also categorized each memory as something they remembered from the past (R response) or they knew had happened in the past (K response) and indicated their ages when each memory occurred. The authors assumed that R and K responses reflected the operation of the episodic and semantic memory systems, respectively. Results showed a reminiscence bump and a retention effect for both R and K responses. The authors discuss the implications of this finding concerning the purported bases of the reminiscence bump and the retention effect as well as the notion that aging is more likely to effect episodic memory than semantic memory.     

Bi-hemispheric engagement in the retrieval of autobiographical episodes

Functional magnetic resonance imaging (fMRI) was used to study the neural correlates of neutral, stressful, negative and positive autobiographical memories. The brain activity produced by these different kinds of episodic memory did not differ significantly, but a common pattern of activation for different kinds of autobiographical memory was revealed that included (1) largely bilateral portions of the medial and superior temporal lobes, hippocampus and parahippocampus, (2) portions of the ventral, medial, superior and dorsolateral prefrontal cortex, (3) the anterior and posterior cingulate, including the retrosplenial, cortex, (4) the parietal cortex, and (5) portions of the cerebellum. The brain regions that were mainly activated constituted an interactive network of temporal and prefrontal areas associated with structures of the extended limbic system. The main bilateral activations with left-sided preponderance probably reflected reactivation of complex semantic and episodic self-related information representations that included previously experienced contexts. In conclusion, the earlier view of a strict left versus right prefrontal laterality in the retrieval of semantic as opposed to episodic autobiographical memory, may have to be modified by considering contextual variables such as task demands and subject variables. Consequently, autobiographical memory integration should be viewed as based on distributed bi-hemispheric neural networks supporting multi-modal, emotionally coloured components of personal episodes.     

Judgement of confidence in childhood memories

Memory judgement processes, based on the characteristics and associations of retrieved memories such as sensory details and supporting memories, are considered as important as retrieval in several autobiographical memory models. Judgement processes have received less research attention than memory characteristics themselves. The present studies examined memory judgement using qualitative analysis of the reasons participants gave for confidence in retrieved childhood memories. For memories they were confident of, participants cited memory phenomenology, especially sensory and affective details, much more frequently than consistency with other autobiographical knowledge. For memories they were not confident of, participants reported lack of consistency with autobiographical knowledge or with others' memories more often than memory phenomenology as reasons for their uncertainty. Participants' comments also revealed several metacognitive beliefs about the relationship between memory characteristics and accuracy. These data are consistent with two‐process models of memory judgement associated with true versus false memories. Copyright © 2007 John Wiley & Sons, Ltd.     

The association of personal semantic memory to identity representations: insight into higher-order networks of autobiographical contents

Identity representations are higher-order knowledge structures that organise autobiographical memories on the basis of personality and role-based themes of one’s self-concept. In two experiments, the extent to which different types of personal semantic content are reflected in these higher-order networks of memories was investigated. Healthy, young adult participants generated identity representations that varied in remoteness of formation and verbally reflected on these themes in an open-ended narrative task. The narrative responses were scored for retrieval of episodic, experience-near personal semantic and experience-far (i.e., abstract) personal semantic contents. Results revealed that to reflect on remotely formed identity representations, experience-far personal semantic contents were retrieved more than experience-near personal semantic contents. In contrast, to reflect on recently formed identity representations, experience-near personal semantic contents were retrieved more than experience-far personal semantic contents. Although episodic memory contents were retrieved less than both personal semantic content types to reflect on remotely formed identity representations, this content type was retrieved at a similar frequency as experience-far personal semantic content to reflect on recently formed identity representations. These findings indicate that the association of personal semantic content to identity representations is robust and related to time since acquisition of these knowledge structures.     

Memories defining the self in Alzheimer’s disease

ABSTRACT

There is a debate over the extent to which personal identity or the self is preserved in patients with Alzheimer’s disease (AD). Autobiographical memory deficits at early stages of AD could contribute to altering patients’ self. However, the nature of the relationship between autobiographical memory deficits and the self in AD has not been much investigated experimentally. In the present study, we aimed to investigate the integrative meaning of self-defining memories (SDMs) in early stages of AD and to analyse its relationship with the self-concept. The results showed that, when compared to the control group, AD patients less frequently extracted meaning from their SDMs and the meaning was less frequently tied to the self. Patients exhibited some altered aspects of the self-concept (i.e., complexity and strength), though some other components still persisted (i.e., valence and certainty). Correlation analyses showed that the impaired integrative meaning in the AD group was correlated with some changes in self-concept. We suggest that integrative meaning may act as a bridge between autobiographical memories and the self-concept, with reduced integration abilities appearing as a potential mechanism for the deterioration of the self-concept in AD.