Age-related positivity effect in emotional memory consolidation from middle age to late adulthood.

Background: While younger adults are more likely to attend to, process, and remember negative relative to positive information, healthy older adults show the opposite pattern. The current study evaluates when, exactly, this positivity shift begins, and how it influences memory performance for positive, negative, and neutral information. Methods: A total of 274 healthy early middle-aged (35-47), late middle-aged (48-59), and older adults (>59) viewed scenes consisting of a negative, positive, or a neutral object placed on a plausible neutral background, and rated each scene for its valence and arousal. After 12 h spanning a night of sleep (n = 137) or a day of wakefulness (n = 137), participants completed an unexpected memory test during which they were shown objects and backgrounds separately and indicated whether the scene component was the "same," "similar," or "new" to what they viewed during the study session. Results and conclusions: We found that both late middle-aged and older adults rated positive and neutral scenes more positively compared to early middle-aged adults. However, only older adults showed better memory for positive objects relative to negative objects, and a greater positive memory trade-off magnitude (i.e., remembering positive objects at the cost of their associated neutral backgrounds) than negative memory trade-off magnitude (i.e., remembering negative objects at the cost of their associated neutral backgrounds). Our findings suggest that while the positivity bias may not emerge in memory until older adulthood, a shift toward positivity in terms of processing may begin in middle age.

More organized white matter is associated with positivity bias in older adults.

On average, healthy older adults prefer positive over neutral or negative stimuli. This positivity bias is related to memory and attention processes and is linked to the function and structure of several interconnected brain areas. However, the relationship between the positivity bias and white matter integrity remains elusive. The present study examines how white matter organization relates to the degree of the positivity bias among older adults. We collected imaging and behavioral data from 25 individuals (12 females, 13 males, and a mean age of 77.32). Based on a functional memory task, we calculated a Pos-Neg score, reflecting the memory for positively valenced information over negative information, and a Pos-Neu score, reflecting the memory for positively valenced information over neutral information. Diffusion-weighted magnetic resonance imaging data were processed using Tract-Based Spatial Statistics. We performed two non-parametric permutation tests to correlate whole brain white matter integrity and the Pos-Neg and Pos-Neu scores while controlling for age, sex, and years of education. We observed a statistically significant positive association between the Pos-Neu score and white matter integrity in multiple brain connections, mostly frontal. The results did not remain significant when including verbal episodic memory as an additional covariate. Our study indicates that the positivity bias in memory in older adults is associated with more organized white matter in the connections of the frontal brain. While these frontal areas are critical for memory and executive processes and have been related to pathological aging, more extensive studies are needed to fully understand their role in the positivity bias and the potential for therapeutic interventions.

Individual Differences in Older Adult Frontal Lobe Function Relate to Memory and Neural Activity for Self-Relevant and Emotional Content.

OBJECTIVES: Older adults show memory benefits for self-relevant and emotional content, but there are individual differences in this effect. It has been debated whether processing of self-relevant and emotional information relies on similar processes to one another. We examined whether variation in frontal lobe (FL) function among older adults related similarly to the processing of self-relevant information as it did to emotional information, or whether these relations diverged. METHODS: While undergoing fMRI, participants (ages 60-88) viewed positive, negative, and neutral objects, and imagined placing those objects in either their home or a stranger's home. Participants completed a surprise memory test outside of the MRI. In a separate session, a cognitive battery was collected and composite scores measuring FL and medial temporal lobe function were computed and related to the behavioral memory performance and the neural engagement during fMRI. RESULTS: Behaviorally, FL function related to memory for self-relevant, but not emotional content. Older adults with higher FL function demonstrated reduced self-bias in memory performance. During the processing of self-relevant stimuli, independent of emotion, levels of activity in the middle frontal gyrus showed positive associations with FL function. This relationship was not driven by compensatory activity or disruptions to nonself-relevant neutral content. DISCUSSION: These findings point to divergence in the cognitive functions relating to memory enhancements for self- and emotional-relevance. The results further suggest self-relevance as a mnemonic device for older adults, especially in those with lower FL function.

How list composition affects the emotional enhancement of memory in younger and older adults.

Young adults show an immediate emotional enhancement of memory (EEM) when emotional and non-emotional information are presented in mixed lists but not pure lists, but it is unclear whether older adults' memories also benefit from the cognitive factors producing the list-composition effect. The present study examined whether the list-composition effect extended to older adults (55+), testing the following alternatives: (1) younger and older adults could show the list-composition effect, (2) due to age-related decreases in cognitive resources, older adults may show weaker effects of list-composition, or (3) due to age-related positivity effects, older adults' list-composition effect may vary by valence. Results supported the first alternative: the list-composition effect occurred for older as well as younger adults, when testing memory for pictures (Experiment 1) or words (Experiment 2). In a third experiment, we explored whether mixing information at only encoding or retrieval (and blocking in the other phase) would suffice for the list composition effect to occur. Results revealed that mixed encoding/blocked retrieval did not elicit the EEM in either age group. Overall, the results suggest age-related stability in the cognitive processes that give rise to the immediate EEM.

The effects of cognitive reappraisal and sleep on emotional memory formation.

Emotion regulation (i.e. either up- or down-regulating affective responses to emotional stimuli) has been shown to modulate long-term emotional memory formation. Further, research has demonstrated that the emotional aspects of scenes are preferentially remembered relative to neutral aspects (known as the emotional memory trade-off effect). This trade-off is often enhanced when sleep follows learning, compared to an equivalent period of time spent awake. However, the interactive effects of sleep and emotion regulation on emotional memory are poorly understood. We presented 87 participants with pictures of neutral or negative objects on neutral backgrounds paired with instructions to either increase or decrease their emotional response by altering personal relevance, or to passively view the stimuli. Following a 12 h period of sleep or wakefulness, participants were tested for their memory of objects and backgrounds separately. Although we replicated the emotional memory trade-off effect, no differences in the magnitude of the trade-off effect were observed between regulation conditions. Sleep improved all aspects of memory, but it did not preferentially benefit memory for emotional components of scenes. Irrespective of a period of sleep or wake following encoding, findings suggest emotion regulation during encoding did not influence memory for emotional items at a 12-hour delay.

Empathy, memory, and aging during the COVID-19 pandemic.

Recently, there has been increasing attention to the interaction between empathy and memory. During the COVID-19 pandemic, a period when empathy played a key role in people's behaviors, we assessed the relationship between empathy and memory. In this pre-registered report, we used memory accuracy for the number of COVID-19 cases as a measure of recent memory and examined its relationship with trait empathy. Moreover, we investigated whether cognitive vs. affective empathy differently associate with one's memory for the number of COVID-19 cases, given evidence for distinct mechanisms for the two aspects of empathy. Finally, we assessed how age is related to empathy-memory associations. To address these questions, we used the Boston College COVID-19 Dataset, which included surveys assessing dispositional empathy and memory for the number of confirmed COVID-19 cases during the first wave of the pandemic. Empathy was not associated with memory accuracy for the confirmed cases when using an empathy measure that combined both cognitive and affective empathy. However, when using a measure that separately assessed cognitive and affective empathy, only affective empathy, specifically the personal distress subscale, was associated with greater memory accuracy. There was no age-related difference in memory accuracy despite age-related decreases in affective empathy. Results suggest that individuals with greater affective empathy (i.e., greater tendency to feel discomfort by the suffering of others) can have more accurate memory for details of an ongoing empathy-evoking situation. Findings are discussed in the context of motivation and emotional arousal. The current study provides ecological evidence to corroborate the interplay of empathy and memory.

Perceived event resolution-rather than time-allows older adults to reduce the negativity of their memories.

In addition to showing greater memory positivity soon after negative events, older adults can be more likely than younger adults to show decreases in memory negativity as events grow more distant. We recently showed that this latter effect was not present when adults were asked to rate memories of the initial phase of the COVID-19 pandemic (March-May 2020): after a short (June/July 2020) and long delay (October/November 2020), older age was associated with greater reflections on positive aspects, but with no difference in negative aspects. We suggested that older adults did not show decreased negativity because the pandemic was still prevalent in their daily lives. The present study examines whether perceived event resolution-rather than time on its own-may be necessary to show age-related decreases in negativity by surveying participants during a time when many may have felt like the pandemic had resolved (Summer 2021). Once again, age was associated with increased ratings of the positive aspects, but at this timepoint, age was also associated with decreased ratings of the negative aspects. These results suggest that older adults may more successfully decrease the negativity of their memories compared to younger adults only when they feel that events have resolved.

Cognitive decline, socioemotional change, or both? How the science of aging can inform future research on sacrificial moral dilemmas.

Older adults comprise the fastest-growing population in the United States. By exercising their right to vote, guiding the value systems of future generations, and holding political office, they shape the moral context of society. It is therefore imperative that we understand older adults' capacity for moral decision-making. Although the vast majority of research on moral decision-making has either focused specifically on younger adults or has not considered age, recent work points to age-related differences in sacrificial moral decision-making, with cognitively healthy older adults making more deontological decisions relative to younger adults. Although only a small number of studies have to date examined age-related differences, there is a wealth of relevant literature on cognitive aging, as well as on sacrificial moral decision-making in younger adults, that point to possible mechanistic explanations for the observed age-related differences. The goal of this review is to situate these age-related differences in sacrificial moral decision-making in the context of these existing literatures in order to guide future, theory-informed, research in this area. We specifically highlight age-related decline in cognitive abilities purported to support utilitarian moral decision-making in younger adults, along with age-related changes to socioemotional information processing as potential mechanistic explanations for these age-related differences. The last section of this review discusses how age-related neural changes may contribute to both cognitive decline and motivational shifts, highlighting the importance for future research to understand brain-behavior relationships on the topic of sacrificial moral decision-making and aging.

Age-related differences in Default Mode Network resting-state functional connectivity but not gray matter volume relate to sacrificial moral decision-making and working memory performance.

Older adults make fewer utilitarian decisions than younger adults during sacrificial moral dilemmas, which are associated with age-related reductions in Default Mode Network resting-state functional connectivity. Decreases on tasks associated with fluid cognitive abilities, such as working memory capacity, are also associated with age-related Default Mode Network changes. Regions within this network demonstrate some of the greatest age-related gray matter atrophy. Age-related changes in structure and function of the Default Mode Network may be associated with poorer working memory capacity and reduced utilitarian moral decision-making. Alternatively, recent theories suggest that age-related changes to Default Mode Network function may be adaptive in the context of tasks that include socioemotional components. As such, reduced within-network resting-state functional connectivity of the Default Mode Network may be associated with differential outcomes in moral decision-making for younger and older adults. In the present study, there were no age-related differences in working memory capacity. Older adults were less likely than younger adults to indicate the utilitarian option when trials involved Instrumental harm. Generally, increased within-network resting-state functional connectivity of the Default Mode Network was associated with better working memory performance in both groups, and reduced bias to endorse the utilitarian option during Incidental dilemmas compared to Instrumental dilemmas in younger adults. Older adults with similar moral decision-making behavior to younger adults demonstrated increased coupling between Default Mode Network and Salience Network regions. These findings suggest that Default Mode Network functional integrity may be differentially associated with age-related changes to working memory capacity and sacrificial moral decision-making.

Sleep preferentially consolidates negative aspects of human memory: Well-powered evidence from two large online experiments.

Research suggests that sleep benefits memory. Moreover, it is often claimed that sleep selectively benefits memory for emotionally salient information over neutral information. However, not all scientists are convinced by this relationship [e.g., J. M. Siegel. Curr. Sleep Med. Rep., 7, 15-18 (2021)]. One criticism of the overall sleep and memory literature-like other literature-is that many studies are underpowered and lacking in generalizability [M. J. Cordi, B. Rasch. Curr. Opin. Neurobiol., 67, 1-7 (2021)], thus leaving the evidence mixed and confusing to interpret. Because large replication studies are sorely needed, we recruited over 250 participants spanning various age ranges and backgrounds in an effort to confirm sleep's preferential emotional memory consolidation benefit using a well-established task. We found that sleep selectively benefits memory for negative emotional objects at the expense of their paired neutral backgrounds, confirming our prior work and clearly demonstrating a role for sleep in emotional memory formation. In a second experiment also using a large sample, we examined whether this effect generalized to positive emotional memory. We found that while participants demonstrated better memory for positive objects compared to their neutral backgrounds, sleep did not modulate this effect. This research provides strong support for a sleep-specific benefit on memory consolidation for specifically negative information and more broadly affirms the benefit of sleep for cognition.

How the 2020 US Presidential election impacted sleep and its relationship to public mood and alcohol consumption.

OBJECTIVES: Major sociopolitical events can influence the general public's affective state and other affect-related processes, such as sleep. Here, we investigated the extent that the 2020 US presidential election impacted sleep, public mood, and alcohol consumption. We also explored the relationship between affect and sleep changes during the peak period of election stress. PARTICIPANTS: US-residing (n = 437) and non-US-residing (n = 106) participants were recruited online for participation in the study. METHODS: A non-representative, convenience sample responded to daily assessments of their affect, sleep, and alcohol consumption during a baseline period (October 1-13, 2020) and in the days surrounding the 2020 US Election (October 30-November 12, 2020). RESULTS: Analyses determined changes within and between US and non-US participants. Election Day evoked significantly reduced sleep amount and efficiency, coupled with heightened stress, negative affect, and increased alcohol use. While US participants were significantly more impacted in a number of domains, non-US participants also reported reduced sleep and greater stress compared to baseline. Across participants, disrupted sleep on Election Night correlated with changes in emotional well-being and alcohol consumption on Election Day. CONCLUSION: These results suggest that major sociopolitical events can have global impacts on sleep that may interact with significant fluctuations in public mood and well-being. Further, while the largest impact is on the local population, these results suggest that the effects can extend beyond borders. These findings highlight the potential impact of future sociopolitical events on public well-being.

Moral decision-making during the COVID-19 pandemic: Associations with age, negative affect, and negative memory.

The COVID-19 pandemic provided the opportunity to determine whether age-related differences in utilitarian moral decision-making during sacrificial moral dilemmas extend to non-sacrificial dilemmas in real-world settings. As affect and emotional memory are associated with moral and prosocial behaviors, we also sought to understand how these were associated with moral behaviors during the 2020 spring phase of the COVID-19 pandemic in the United States. Older age, higher negative affect, and greater reports of reflecting on negative aspects of the pandemic were associated with higher reported purchase of hard-to-find goods, while older age and higher negative affect alone were associated with higher reported purchase of hard-to-find medical supplies. Older age was associated with what appeared at first to be non-utilitarian moral behaviors with regard to the purchasing of these supplies; However, they also reported distributing these goods to family members rather than engaging in hoarding behaviors. These findings suggest that advancing age may be associated with engagement in utilitarian moral decision-making in real-world settings more than the sacrificial moral decision-making literature would suggest.

Consciousness as a Memory System.

We suggest that there is confusion between why consciousness developed and what additional functions, through continued evolution, it has co-opted. Consider episodic memory. If we believe that episodic memory evolved solely to accurately represent past events, it seems like a terrible system-prone to forgetting and false memories. However, if we believe that episodic memory developed to flexibly and creatively combine and rearrange memories of prior events in order to plan for the future, then it is quite a good system. We argue that consciousness originally developed as part of the episodic memory system-quite likely the part needed to accomplish that flexible recombining of information. We posit further that consciousness was subsequently co-opted to produce other functions that are not directly relevant to memory per se, such as problem-solving, abstract thinking, and language. We suggest that this theory is compatible with many phenomena, such as the slow speed and the after-the-fact order of consciousness, that cannot be explained well by other theories. We believe that our theory may have profound implications for understanding intentional action and consciousness in general. Moreover, we suggest that episodic memory and its associated memory systems of sensory, working, and semantic memory as a whole ought to be considered together as the conscious memory system in that they, together, give rise to the phenomenon of consciousness. Lastly, we suggest that the cerebral cortex is the part of the brain that makes consciousness possible, and that every cortical region contributes to this conscious memory system.

Investigating the effects of sleep and sleep loss on the different stages of episodic emotional memory: A narrative review and guide to the future.

For two decades, sleep has been touted as one of the primary drivers for the encoding, consolidation, retention, and retrieval of episodic emotional memory. Recently, however, sleep's role in emotional memory processing has received renewed scrutiny as meta-analyses and reviews have indicated that sleep may only contribute a small effect that hinges on the content or context of the learning and retrieval episodes. On the one hand, the strong perception of sleep's importance in maintaining memory for emotional events may have been exacerbated by publication bias phenomena, such as the "winner's curse" and "file drawer problem." On the other hand, it is plausible that there are sets of circumstances that lead to consistent and reliable effects of sleep on emotional memory; these circumstances may depend on factors such as the placement and quality of sleep relative to the emotional experience, the content and context of the emotional experience, and the probes and strategies used to assess memory at retrieval. Here, we review the literature on how sleep (and sleep loss) influences each stage of emotional episodic memory. Specifically, we have separated previous work based on the placement of sleep and sleep loss in relation to the different stages of emotional memory processing: (1) prior to encoding, (2) immediately following encoding during early consolidation, (3) during extended consolidation, separated from initial learning, (4) just prior to retrieval, and (5) post-retrieval as memories may be restructured and reconsolidated. The goals of this review are three-fold: (1) examine phases of emotional memory that sleep may influence to a greater or lesser degree, (2) explicitly identify problematic overlaps in traditional sleep-wake study designs that are preventing the ability to better disentangle the potential role of sleep in the different stages of emotional memory processing, and (3) highlight areas for future research by identifying the stages of emotional memory processing in which the effect of sleep and sleep loss remains under-investigated. Here, we begin the task of better understanding the contexts and factors that influence the relationship between sleep and emotional memory processing and aim to be a valuable resource to facilitate hypothesis generation and promote important future research.

Distinct stress-related changes in intrinsic amygdala connectivity predict subsequent positive and negative memory performance.

Experiencing stress before an event can influence how that event is later remembered. In the current study, we examine how individual differences in one's physiological response to a stressor are related to changes to underlying brain states and memory performance. Specifically, we examined how changes in intrinsic amygdala connectivity relate to positive and negative memory performance as a function of stress response, defined as a change in cortisol. Twenty-five participants underwent a social stressor before an incidental emotional memory encoding task. Cortisol samples were obtained before and after the stressor to measure individual differences in stress response. Three resting state scans (pre-stressor, post-stressor/pre-encoding and post-encoding) were conducted to evaluate pre- to post-stressor and pre- to post-encoding changes to intrinsic amygdala connectivity. Analyses examined relations between greater cortisol changes and connectivity changes. Greater cortisol increases were associated with a greater decrease in prefrontal-amygdala connectivity following the stressor and a reversal in the relation between prefrontal-amygdala connectivity and negative vs. positive memory performance. Greater cortisol increases were also associated with a greater increase in amygdala connectivity with a number of posterior sensory regions following encoding. Consistent with prior findings in non-stressed individuals, pre- to post-encoding increases in amygdala-posterior connectivity were associated with greater negative relative to positive memory performance, although this was specific to lateral rather than medial posterior regions and to participants with the greatest cortisol changes. These findings suggest that stress response is associated with changes in intrinsic connectivity that have downstream effects on the valence of remembered emotional content.

The power of negative and positive episodic memories.

The power of episodic memories is that they bring a past moment into the present, providing opportunities for us to recall details of the experiences, reframe or update the memory, and use the retrieved information to guide our decisions. In these regards, negative and positive memories can be especially powerful: Life's highs and lows are disproportionately represented in memory, and when they are retrieved, they often impact our current mood and thoughts and influence various forms of behavior. Research rooted in neuroscience and cognitive psychology has historically focused on memory for negative emotional content. Yet the study of autobiographical memories has highlighted the importance of positive emotional memories, and more recently, cognitive neuroscience methods have begun to clarify why positive memories may show powerful relations to mental wellbeing. Here, we review the models that have been proposed to explain why emotional memories are long-lasting (durable) and likely to be retrieved (accessible), describing how in overlapping-but distinctly separable-ways, positive and negative memories can be easier to retrieve, and more likely to influence behavior. We end by identifying potential implications of this literature for broader topics related to mental wellbeing, education, and workplace environments.

Representing the Good and Bad: fMRI signatures during the encoding of multisensory positive, negative, and neutral events.

Few studies have examined how multisensory emotional experiences are processed and encoded into memory. Here, we aimed to determine whether, at encoding, activity within functionally-defined visual- and auditory-processing brain regions discriminated the emotional category (i.e., positive, negative, or neutral) of the multisensory (audio-visual) events. Participants incidentally encoded positive, negative, and neutral multisensory stimuli during event-related functional magnetic resonance imaging (fMRI). Following a 3-h post-encoding delay, their memory for studied stimuli was tested, allowing us to identify emotion-category-specific subsequent-memory effects focusing on medial temporal lobe regions (i.e., amygdala, hippocampus) and visual- and auditory-processing regions. We used a combination of univariate and multivoxel pattern fMRI analyses (MVPA) to examine emotion-category-specificity in mean activity levels and neural patterning, respectively. Univariate analyses revealed many more visual regions that showed negative-category-specificity relative to positive-category-specificity, and auditory regions only showed negative-category-specificity. These results suggest that negative emotion is more closely tied to information contained within sensory regions, a conclusion that was supported by the MVPA analyses. Functional connectivity analyses further revealed that the visual amplification of category-selective processing is driven, in part, by mean signal from the amygdala. Interestingly, while stronger representations in visuo-auditory regions were related to subsequent-memory for neutral multisensory stimuli, they were related to subsequent-forgetting of positive and negative stimuli. Neural patterning in the hippocampus and amygdala were related to memory for negative multisensory stimuli. These results provide new evidence that negative emotional stimuli are processed with increased engagement of visuosensory regions, but that this sensory engagement-that generalizes across the entire emotion category-is not the type of sensory encoding that is most beneficial for later retrieval.

Age and chronotype influenced sleep timing changes during the first wave of the COVID-19 pandemic.

Social restrictions necessary to reduce the spread of coronavirus disease 2019 (COVID-19) profoundly changed how we socialised, worked and, for students, attended classes. Interestingly, significant sleep pattern shifts occurred in the context of pandemic-related social restrictions. Whether age and chronotype influenced these sleep pattern changes remains poorly understood. In this pre-registered (https://osf.io/4a3fx), web-based study, United States residents reported, in one-time assessments, demographic information, self-reported chronotype using the reduced Morningness-Eveningness Questionnaire, and pre-pandemic and pandemic first wave sleep timing using the Ultrashort Munich Chronotype Questionnaire. Participants reported sleep phase delays, reduced social jetlag (SJL) and reduced social sleep restriction (SSR) during the first wave of the pandemic compared to pre-pandemic. Pandemic-related changes in SJL and SSR varied with participants' age and self-reported chronotype. Young adults reported the greatest reductions in SJL and young adults and individuals with evening chronotypes reported the greatest reductions in SSR. We conclude that these groups may have been the most vulnerable to social-biological sleep timing desynchrony under pre-pandemic social, occupational, and educational schedules.

Aging, Empathy, and Prosocial Behaviors During the COVID-19 Pandemic.

OBJECTIVES: Previous literature suggests age-related increases in prosociality. Does such an age-prosociality relationship occur during the coronavirus disease 2019 (COVID-19) pandemic, or might the pandemic-as a stressor that may differently influence young and older adults-create a boundary condition on the relationship? If so, can empathy, a well-known prosocial disposition, explain the age-prosociality relationship? This study investigated these questions and whether the target (distant others compared to close others) of prosocial behaviors differs by age. METHODS: Participants completed a series of surveys on dispositional empathy and prosocial behaviors for a study assessing their experiences during the COVID-19 pandemic. There were 330 participants (aged 18-89) from the United States who completed all of the surveys included in the present analyses. RESULTS: Age was positively related to greater prosociality during the pandemic. Although empathy was positively associated with individuals' prosociality, it did not account for the age-prosociality association. Interestingly, increasing age was associated with greater prosocial behaviors toward close others (i.e., family, friends). DISCUSSION: Results are discussed in the context of socioemotional goals and substantiate that findings of age differences in prosocial behaviors occur during the period of limited resources and threat associated with the COVID-19 pandemic.