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Self-knowledge is a type of personal semantic knowledge that concerns one's self-image and personal identity. It has most often been operationalized as the summary of one's personality traits ("I am a stubborn person"). Interestingly, recent studies have revealed that the neural correlates of self-knowledge can be dissociated from those of general semantic and episodic memory in young adults. However, studies of "dedifferentiation" or loss of distinctiveness of neural representations in ageing suggest that the neural correlates of self-knowledge might be less distinct from those of semantic and episodic memory in older adults. We investigated this question in an event-related potential (ERP) study with 28 young and 26 older adults while they categorised personality traits for their self-relevance (self-knowledge conditions), and their relevance to certain groups of people (general semantic condition). Participants then performed a recognition test for previously seen traits (episodic condition). The amplitude of the late positive component (LPC), associated with episodic recollection processes, differentiated the self-knowledge, general semantic, and episodic conditions in young adults, but not in older adults. However, in older adults, participants with higher composite episodic memory scores had more differentiated LPC amplitudes across experimental conditions. Moreover, consistent with the fact that age-related neural dedifferentiation may be material and region specific, in both age groups some differences between memory types were observed for the N400 component, associated with semantic processing. Taken together, these findings suggest that declarative memory subtypes are less distinct in ageing, but that the amount of differentiation varies with episodic memory function. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic created a unique set of circumstances in which to investigate collective memory and future simulations of events reported during the onset of a potentially historic event. Between early April and late June 2020, we asked over 4,000 individuals from 15 countries across four continents to report on remarkable (a) national and (b) global events that (i) had happened since the first cases of COVID-19 were reported, and (ii) they expected to happen in the future. Whereas themes of infections, lockdown, and politics dominated global and national past events in most countries, themes of economy, a second wave, and lockdown dominated future events. The themes and phenomenological characteristics of the events differed based on contextual group factors. First, across all conditions, the event themes differed to a small yet significant degree depending on the severity of the pandemic and stringency of governmental response at the national level. Second, participants reported national events as less negative and more vivid than global events, and group differences in emotional valence were largest for future events. This research demonstrates that even during the early stages of the pandemic, themes relating to its onset and course were shared across many countries, thus providing preliminary evidence for the emergence of collective memories of this event as it was occurring. Current findings provide a profile of past and future collective events from the early stages of the ongoing pandemic, and factors accounting for the consistencies and differences in event representations across 15 countries are discussed. [ABSTRACT FROM AUTHOR]