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.     

The neural bases of the constructive nature of autobiographical memories studied with a self-paced fMRI design

In Conway and Pleydell-Pearce's model (2000), autobiographical memories are viewed as transitory mental representations, more often generated in an effortful way. An important claim of the model concerns the dynamic process that evolves over time, from the left prefrontal areas to posterior regions, to retrieve specific memories. The present work aims at investigating, using fMRI, the temporal distribution of effortful autobiographical memory construction. In addition, a self-paced design was implemented to elucidate the question of the timing window required to evoke recollections. The results showed a large pattern of brain regions, which included the two major poles of activation predicted by Conway and Pleydell-Pearce's model. Likewise, we were able to detect the earlier implication of the left dorso-lateral prefrontal cortex, by comparison with posterior structures, which seemed to confirm its involvement in the effortful retrieval process. Finally, the self-paced procedure allowed us to refine the timing window necessary to construct past events.     

Psychophysics with children: Investigating the effects of attentional lapses on threshold estimates

When assessing the perceptual abilities of children, researchers tend to use psychophysical techniques designed for use with adults. However, children’s poorer attentiveness might bias the threshold estimates obtained by these methods. Here, we obtained speed discrimination threshold estimates in 6- to 7-year-old children in UK Key Stage 1 (KS1), 7- to 9-year-old children in Key Stage 2 (KS2), and adults using three psychophysical procedures: QUEST, a 1-up 2-down Levitt staircase, and Method of Constant Stimuli (MCS). We estimated inattentiveness using responses to “easy” catch trials. As expected, children had higher threshold estimates and made more errors on catch trials than adults. Lower threshold estimates were obtained from psychometric functions fit to the data in the QUEST condition than the MCS and Levitt staircases, and the threshold estimates obtained when fitting a psychometric function to the QUEST data were also lower than when using the QUEST mode. This suggests that threshold estimates cannot be compared directly across methods. Differences between the procedures did not vary significantly with age group. Simulations indicated that inattentiveness biased threshold estimates particularly when threshold estimates were computed as the QUEST mode or the average of staircase reversals. In contrast, thresholds estimated by post-hoc psychometric function fitting were less biased by attentional lapses. Our results suggest that some psychophysical methods are more robust to attentiveness, which has important implications for assessing the perception of children and clinical groups.

     

Ratings of the auditory and visual similarity of consonants: Implications for research

A set of rating data was collected which compared the visual similarity of consonants to the auditory similarity of the same letters. Analysis of the rating patterns raises important questions about the use of similarity data in drawing conclusions about mode of memory coding in a variety of situations.     

More on the measurement of spontaneous alternation

Still and MacMillan (1977) suggested the negative of the Phi coefficient (- φ) as a measure of free-trial spontaneous alternation. This new index is compared with the Adjusted Alternation Ratio (AAR), previously developed by Manning (1973b). It is concluded that there are many situations in which the AAR is a more useful measure. Other issues in assessing spontaneous alternation noted by Still and MacMillan are discussed.     

Putting personality in social context: extraversion, emergent leadership, and the availability of rewards

The present research tested relations between extraversion and emergent leadership among men in situations that differed in potential reward availability. Four-person groups of men engaged in a Leaderless Group Discussion (LGD) task and were randomly assigned to be evaluated by an attractive female observer, an attractive male observer, or not be evaluated. Evolutionary theories suggest that impressing a female evaluator in an intrasexually competitive situation should hold greater reward potential for men than impressing either a male evaluator or no evaluator. Accordingly, more extraverted men (who are more sensitive to reward cues) should display more group leadership when being evaluated by a woman than either a man or no one. Self-and peer ratings confirmed that more extraverted men were significantly more likely to emerge as leaders, but only in the female-evaluator condition. The results are discussed in terms of the interplay between personality, situational factors, and evolutionary principles.     

The availability explanation of excessive plausibility assessments

The assessment of hypotheses in hypothesis generation involves a comparison between those hypotheses that have been generated (specified) and those that are not generated (unspecified). Experiment 1 was an investigation of an “availability explanation” for subjects' overconfidence in the probability of specified hypotheses. The conjecture is that subjects have difficulty retrieving unspecified hypotheses from memory. Therefore, the underpopulated set of unspecified hypotheses is assessed as less probable then it actually is and the specified set is assessed as more probable. Two manipulations to increase the availability of unspecified hypotheses were investigated. One involved explicitly requesting subjects to populate the unspecified set; the other was a computer presentation of candidate unspecified hypotheses. Results of experiment 1 were that assessment overconfidence for both experimental groups was reduced. The results support the conjecture that the availability heuristic is at least partially responsible for subjects' overconfidence. The main result of experiment 2 was that the overconfidence bias persisted with different assessment methods for both subject-generated and experimenter-supplied hypotheses.     

Predictors of depressive symptoms among breast cancer patients during the first year post diagnosis

It is important to identify predictors of psychological health among breast cancer patients that can be relatively easily identified by medical care providers. This article investigates the role of one class of such potential predictors: easily identified demographics that have potential social and/or practical implications. Specifically, we examined whether income, marital status, presence of children in the home, education, travel distance, age and rurality interact with time to predict psychological health over the first year post diagnosis. Two hundred and twenty five breast cancer patients receiving radiation treatment completed four surveys over the course of 13 months that included measures of both their physical health and depressive symptoms. The results revealed that women who were not married had children living in the home or had to travel long distances to receive radiation treatment reported higher levels of depressive symptoms across the entire study. Women with lower incomes reported increased depressive symptoms, but only after the completion of treatment. Younger women reported elevated depressive symptoms during initial treatment, but this effect dissipated after the completion of treatment. The current results suggest that demographic patient characteristics may indeed be useful in identifying both when and for whom depressive symptoms are particularly likely to be problematic.