Aging Increases Prosocial Motivation for Effort

How effort-based self-interest motivation shapes altruistic donation behavior and brain responses

Prosocial behaviors are central to individual and societal well-being. Although the relationship between effort and prosocial behavior is increasingly studied, the impact of effort-based self-interested motivation on prosocial behavior has received less attention. In the current study, we carried out two experiments to examine the effect of motivation to obtain a reward for oneself on donation behavior and brain response. We observed that individuals who accumulated more money in the effort-expenditure rewards task (EEfRT) donated a lower proportion of their earnings. The sigmoid model fitted participants' choices in the EEfRT task, and the effort-reward bias and sigma parameters negatively correlated with the amount of money donated in the donation task. Additionally, the effort-reward bias and sigma parameters negatively predicted N2 amplitude during processing of charitable donation-related information. We propose that individuals who exhibit a lower level of effort-based self-interest motivation may allocate more cognitive control or attentional resources when processing information related to charitable donations. Our work adds weight to understanding the relationship between effort-based self-interest motivation and prosocial behavior and provides electrophysiological evidence.

Brain stimulation over the left DLPFC enhances motivation for effortful rewards in patients with major depressive disorder

BACKGROUND

Amotivation is a typical feature in major depressive disorder (MDD), which produces reduced willingness to exert effort. The dorsolateral prefrontal cortex (DLPFC) is a crucial structure in goal-directed actions and therefore is a potential target in modulating effortful motivation. However, it remains unclear whether the intervention is effective for patients with MDD.

METHODS

We employed transcranial magnetic stimulation (TMS), computational modelling and event-related potentials (ERPs) to reveal the causal relationship between the left DLPFC and motivation for effortful rewards in MDD. Fifty patients underwent both active and sham TMS sessions, each followed by performing an Effort-Expenditure for Rewards Task, during which participants chose and implemented between low-effort/low-reward and high-effort/high-reward options.

RESULTS

The patients showed increased willingness to exert effort for rewards during the DLPFC facilitated session, compared with the sham session. They also had a trend in larger P3 amplitude for motivated attention toward chosen options, larger CNV during preparing for effort exertion, and larger SPN during anticipating a high reward. Besides, while behavior indexes for effortful choices were negatively related to depression severity in the sham session, this correlation was weakened in the active stimulation session.

CONCLUSIONS

These findings provide behavioral, computational, and neural evidence for the left DLPFC on effortful motivation for rewards. Facilitated DLPFC improves motor preparation and value anticipation after making decisions especially for highly effortful rewards in MDD. Facilitated DLPFC also has a potential function in enhancing motivated attention during cost-benefit trade-off. This neuromodulation effect provides a potential treatment for improving motivation in clinics.

Human ventromedial prefrontal cortex is necessary for prosocial motivation

Ventromedial prefrontal cortex (vmPFC) is vital for decision-making. Functional neuroimaging links vmPFC to processing rewards and effort, while parallel work suggests vmPFC involvement in prosocial behaviour. However, the necessity of vmPFC for these functions is unknown. Patients with rare focal vmPFC lesions (n = 25), patients with lesions elsewhere (n = 15) and healthy controls (n = 40) chose between rest and exerting effort to earn rewards for themselves or another person. vmPFC damage decreased prosociality across behavioural and computational measures. vmPFC patients earned less, discounted rewards by effort more, and exerted less force when another person benefited, compared to both control groups. Voxel-based lesion mapping revealed dissociations between vmPFC subregions. While medial damage led to antisocial behaviour, lateral damage increased prosocial behaviour relative to patients with damage elsewhere. vmPFC patients also showed reduced effort sensitivity overall, but reward sensitivity was limited to specific subregions. These results reveal multiple causal contributions of vmPFC to prosocial behaviour, effort and reward.

Probing apathy in children and adolescents with the Apathy Motivation Index-Child version

Apathy is linked to mental health and altered neurocognitive functions such as learning and decision-making in healthy adults. Mental health problems typically begin to emerge during adolescence, yet little is known about how apathy develops due to an absence of quantitative measurements specific to young people. Here, we present and evaluate the Apathy Motivation Index-Child Version (AMI-CV) for children and adolescents. We show across two samples of young people (aged 8 to 17 years, total N = 191) tested in schools in the UK and on a smartphone app, that the AMI-CV is a short, psychometrically sound measure to assess levels of apathy and motivation in young people. Similar to adult versions, the AMI-CV captures three distinct apathy domains: Behavioural Activation, Social Motivation and Emotional Sensitivity. The AMI-CV showed excellent construct validity with an alternative measure of apathy and external validity replicating specific links with related mental health traits shown in adults. Our results provide a short measure of self-reported apathy in young people that enables research into apathy development. The AMI-CV can be used in conjunction with the adult version to investigate the impact of levels of apathy across the lifespan.

Iranian community-dwelling older adults' perceptions of prosociality: A qualitative study

BACKGROUND

The world population is aging at an accelerating rate, and prosociality aspects increase in people with age. This study aimed to explore Iranian community-dwelling older adults' perspectives of the prosociality concept.

MATERIALS AND METHODS

This qualitative study was conducted among older adults aged 60 years and older in Qom City, Iran. A purposive sampling method was used to collect data between July and October 2022. Semi-structured interviews were conducted with 25 older adults engaged in various types of prosocial activities. Data were analyzed applying a directed content analysis approach. All interviews were audio recorded, transcribed verbatim, and coded using MAXQDA 20 software.

RESULTS

Overall, 5 main categories and 19 subcategories emerged from the content data analysis. The two emerged categories were related to the predetermined dimensions of the prosociality concept, namely, "prosocial behaviors" and "prosocial dispositions." The remaining three newly emerged categories included "egocentric motives," "facilitators," and "barriers" to prosocial behaviors. As participants reported, "informal spontaneous helping" was the most prevalent subcategory of prosocial behaviors. "Prosocial norms" and "social reward-seeking" were identified as the most common subcategories of prosocial dispositions and egocentric motives, respectively. Likewise, participants mentioned "religious and metaphysic beliefs" and "social distrust" as important facilitators and barriers, respectively.

CONCLUSIONS

The results of this qualitative study provide a new understanding of the prosociality concept among older adults in the context of Iran. In conclusion, to improve prosocial behaviors in this population, the interaction between all factors that influence it such as motives, facilitators, and barriers must be considered.

Increases in prosociality across adulthood: The pure-altruism hypothesis

A growing body of research suggests that prosocial behavior increases across adulthood. Yet, whether these age differences reflect "pure altruistic" or selfish motives, or the developmental mechanisms that underlie them, are largely unknown. Within a value-based decision framework, pure altruistic tendencies can be measured and distinguished from impure altruistic motives through neural-level information. Indeed, age differences in donations appear to be driven by a genuine concern for the well-being of others. Candidate mechanisms behind such pure altruistic changes need to show documented age differences and evidence of causal links to prosocial behavior. As examples, we discuss how three factors that meet these criteria--social norms, mood, and cognitive functioning--might explain age differences in pure altruistic tendencies.

Reduced prosocial motivation and effort in adolescents with conduct problems and callous-unemotional traits

BACKGROUND

Prosocial behaviours - acts that benefit others - are of crucial importance for many species including humans. However, adolescents with conduct problems (CP), unlike their typically developing (TD) peers, demonstrate markedly reduced engagement in prosocial behaviours. This pattern is particularly pronounced in adolescents with CP and high levels of callous-unemotional traits (CP/HCU) who are at increased risk of developing psychopathy in adulthood. While a substantial amount of research has investigated the cognitive-affective mechanisms thought to underlie antisocial behaviour, much less is known about the mechanisms that could explain reduced prosocial behaviours in adolescents with CP.

METHODS

Here we examined the willingness to exert effort to benefit oneself (self) and another person (other, prosocial condition) in children with CP/HCU, CP and lower levels of CU traits (CP/LCU) and their TD peers. The task captured both prosocial choices, and actual effort exerted following prosocial choices, in adolescent boys aged 11-16 (27 CP/HCU; 34 CP/LCU; 33 TD). We used computational modelling to reveal the mechanistic processes involved when choosing prosocial acts.

RESULTS

We found that both CP/HCU and CP/LCU groups were more averse to initiating effortful prosocial acts than TD adolescents - both at a cognitive and at a behavioural level. Strikingly, even if they chose to initiate a prosocial act, the CP/HCU group exerted less effort following this prosocial choice than other groups.

CONCLUSIONS

Our findings indicate that reduced exertion of effort to benefit others may be an important factor that differentiates adolescents with CP/HCU from their peers with CP/LCU. They offer new insights into what might drive low prosocial behaviour in adolescents with CP, including vulnerabilities that may particularly characterise those with high levels of CU traits.

Acute stress reduces effortful prosocial behaviour

Acute stress can change our cognition and emotions, but what specific consequences this has for human prosocial behaviour is unclear. Previous studies have mainly investigated prosociality with financial transfers in economic games and produced conflicting results. Yet a core feature of many types of prosocial behaviour is that they are effortful. We therefore examined how acute stress changes our willingness to exert effort that benefits others. Healthy male participants - half of whom were put under acute stress - made decisions whether to exert physical effort to gain money for themselves or another person. With this design, we could independently assess the effects of acute stress on prosocial, compared to self-benefitting, effortful behaviour. Compared to controls (n = 45), participants in the stress group (n = 46) chose to exert effort more often for self- than for other-benefitting rewards at a low level of effort. Additionally, the adverse effects of stress on prosocial effort were particularly pronounced in more selfish participants. Neuroimaging combined with computational modelling revealed a putative neural mechanism underlying these effects: more stressed participants showed increased activation to subjective value in the dorsal anterior cingulate cortex and anterior insula when they themselves could benefit from their exerted effort relative to when someone else could. By using an effort-based task that better approximates real-life prosocial behaviour and incorporating trait differences in prosocial tendencies, our study provides important insights into how acute stress affects prosociality and its associated neural mechanisms.

The Concept of Prosociality in Later Life and Its Dimensions: A Scoping Review

Objective: The aim of this study was to clarify various aspects and dimensions of the prosociality concept in later life as an important concept that gains significance in people as they age. This concept has been expressed through a variety of dimensions in different studies. Method : This is a scoping review of the relevant literature on the concept of prosociality and its dimensions in later life, including quantitative and qualitative studies. The required data were collected from Web of Science, Scopus, PubMed, ProQuest, and Google Scholar databases between the years 1987 and 2022. Results: First, 877 articles were identified, and after the screening phase, 57 eligible studies were reviewed. Two main categories, prosocial dispositions and prosocial behaviors, and seven subcategories were extracted. The subcategories of prosocial dispositions include empathy, prosocial norms, innate tendencies, and generative desires. Prosocial behaviors subcategories include informal spontaneous helping, formal planned helping, and pro-environmental behaviors. Conclusion: The various aspects and dimensions of the prosociality concept in later life identified in this study can be used as a basis for assessing and planning the promotion of prosociality among older adults.

The influence of generativity on purpose in life is mediated by social support and moderated by prefrontal functional connectivity in at-risk older adults

Objectives

Generativity, the desire and action to improve the well-being of younger generations, is positively associated with purpose in life among older adults. However, the neural basis of generativity and the neurobehavioral factors supporting the relationship between generativity and purpose in life remain unknown. This study aims to identify the functional neuroanatomy of generativity and mechanisms linking generativity with purpose in life in at-risk older adults.

Methods

Fifty-eight cognitively healthy older adults (mean age = 70.78, 45 females) with a family history of Alzheimer's disease were recruited from the PREVENT-AD aging cohort. Participants underwent brain imaging and completed questionnaires assessing generativity, social support, and purpose in life. Mediation models examined whether social support mediated the association between generativity and purpose in life. Seed-to-voxel analyses investigated the association between resting-state functional connectivity (rsFC) to the ventromedial prefrontal cortex (vmPFC) and ventral striatum (VS) and whether this rsFC moderated the relationship between generativity and purpose in life.

Results

Affectionate social support mediated the association between generative desire and purpose in life. Generative desire was associated with rsFC between VS and precuneus and vmPFC and right dorsolateral prefrontal cortex (rdlPFC). The vmPFC-rdlPFC connectivity moderated the association between generative desire and purpose in life.

Discussion

These findings provide insight into how the brain supports social behavior and, separately, purpose in life in at-risk aging. Affectionate social support may be a putative target process to enhance purpose and life in older adults. This knowledge contributes to future developments of personalized interventions that promote healthy aging.

Episodic simulation of helping behavior in younger and older adults during the COVID-19 pandemic

Imagining helping a person in need increases one's willingness to help beyond levels evoked by passively reading the same stories. We examined whether episodic simulation can increase younger and older adults' willingness to help in novel scenarios posed by the COVID-19 pandemic. Across 3 studies we demonstrate that episodic simulation of helping behavior increases younger and older adults' willingness to help during both everyday and COVID-related scenarios. Moreover, we show that imagining helping increases emotional concern, scene imagery, and theory of mind, which in turn relate to increased willingness to help. Studies 2 and 3 also showed that people produce more internal, episodic-like details when imagining everyday compared to COVID-related scenarios, suggesting that people are less able to draw on prior experiences when simulating such novel events. These findings suggest that encouraging engagement with stories of people in need by imagining helping can increase willingness to help during the pandemic.

Increased cognitive effort costs in healthy aging and preclinical Alzheimer's disease

Life-long engagement in cognitively demanding activities may mitigate against declines in cognitive ability observed in healthy or pathological aging. However, the "mental costs" associated with completing cognitive tasks also increase with age and may be partly attributed to increases in preclinical levels of Alzheimer's disease (AD) pathology, specifically amyloid. We test whether cognitive effort costs increase in a domain-general manner among older adults, and further, whether such age-related increases in cognitive effort costs are associated with working memory (WM) capacity or amyloid burden, a signature pathology of AD. In two experiments, we administered a behavioral measure of cognitive effort costs (cognitive effort discounting) to a sample of older adults recruited from online sources (Experiment 1) or from ongoing longitudinal studies of aging and dementia (Experiment 2). Experiment 1 compared age-related differences in cognitive effort costs across two domains, WM and speech comprehension. Experiment 2 compared cognitive effort costs between a group of participants who were rated positive for amyloid relative to those with no evidence of amyloid. Results showed age-related increases in cognitive effort costs were evident in both domains. Cost estimates were highly correlated between the WM and speech comprehension tasks but did not correlate with WM capacity. In addition, older adults who were amyloid positive had higher cognitive effort costs than those who were amyloid negative. Cognitive effort costs may index a domain-general trait that consistently increases in aging. Differences in cognitive effort costs associated with amyloid burden suggest a potential neurobiological mechanism for age-related differences. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Effect of situation similarity on younger and older adults' episodic simulation of helping behaviours

Similar cognitive processes enable us to remember the past (i.e., episodic memory) and simulate future events (i.e., episodic simulation). In the current study, we demonstrate an important role for previous experience when younger and older adults simulate future behaviours. Participants read short descriptions of a person in need of help in scenarios that were more familiar to either younger or older adults (e.g., dealing with dating apps vs writing a cheque). Participants either imagined helping the person or thought about the style of the story (control task), and then rated their willingness to help, scene vividness, emotional concern, and subjective use of theory of mind. Hierarchical mixed effect modelling revealed that both episodic simulation and one's previous experience increased willingness to help, in that participants were more willing to help if they imagined helping and the situation was more familiar to them. Further, in simulated scenarios the relationship between previous experience and willingness to help was mediated by scene vividness and perspective-taking in younger adults, but only by perspective-taking in older adults. Taken together, these findings suggest that situation similarity and episodic simulation increase willingness to help, possibly via different mechanisms in younger and older adults.

Neural representations of vicarious rewards are linked to interoception and prosocial behaviour

Every day we constantly observe other people receiving rewards. Theoretical accounts posit that vicarious reward processing might be linked to people's sensitivity to internal body states (interoception) and facilitates a tendency to act prosocially. However, the neural processes underlying the links between vicarious reward processing, interoception, and prosocial behaviour are poorly understood. Previous research has linked vicarious reward processing to the anterior cingulate gyrus (ACCg) and the anterior insula (AI). Can we predict someone's propensity to be prosocial or to be aware of interoceptive signals from variability in how the ACCg and AI process rewards? Here, participants monitored rewards being delivered to themselves or a stranger during functional magnetic resonance imaging. Later, they performed a task measuring their willingness to exert effort to obtain rewards for others, and a task measuring their propensity to be aware and use interoceptive respiratory signals. Using multivariate similarity analysis, we show that people's willingness to be prosocial is predicted by greater similarity between self and other representations in the ACCg. Moreover, greater dissimilarity in self-other representations in the AI is linked to interoceptive propensity. These findings highlight that vicarious reward is linked to bodily signals in AI, and foster prosocial tendencies through the ACCg.

Altruistic responses to the most vulnerable involve sensorimotor processes

Introduction

Why do people help strangers? Prior research suggests that empathy motivates bystanders to respond to victims in distress. However, this work has revealed relatively little about the role of the motor system in human altruism, even though altruism is thought to have originated as an active, physical response to close others in immediate need. We therefore investigated whether a motor preparatory response contributes to costly helping.

Methods

To accomplish this objective, we contrasted three charity conditions that were more versus less likely to elicit an active motor response, based on the Altruistic Response Model. These conditions described charities that (1) aided neonates versus adults, (2) aided victims requiring immediate versus preparatory support, and (3) provided heroic versus nurturant aid. We hypothesized that observing neonates in immediate need would elicit stronger brain activation in motor-preparatory regions.

Results

Consistent with an evolutionary, caregiving-based theory of altruism, participants donated the most to charities that provided neonates with immediate, nurturant aid. Critically, this three-way donation interaction was associated with increased BOLD signal and gray matter volume in motor-preparatory regions, which we identified in an independent motor retrieval task.

Discussion

These findings advance the field of altruism by shifting the spotlight from passive emotional states toward action processes that evolved to protect the most vulnerable members of our group.

Determinants of Social Cognitive Aging: Predicting Resilience and Risk

This review focuses on conceptual and empirical research on determinants of social cognitive aging. We present an integrated model [the social cognitive resource (SCoRe) framework] to organize the literature and describe how social cognitive resilience is determined jointly by capacity and motivational resources. We discuss how neurobiological aging, driven by genetic and environmental influences, is associated with broader sensory, neural, and physiological changes that are direct determinants of capacity as well as indirect determinants of motivation via their influence on expectation of loss versus reward and cognitive effort valuation. Research is reviewed that shows how contextual factors, such as relationship status, familiarity, and practice, are fundamental to understanding the availability of both types of resource. We conclude with a discussion of the implications of social cognitive change in late adulthood for everyday social functioning and with recommendations for future research.

Preferences for seeking effort or reward information bias the willingness to work

Research suggests that the temporal order in which people receive information about costs and benefits whilst making decisions can influence their choices. But, do people have a preference for seeking information about costs or benefits when making effort-based decisions, and does this impact motivation? Here, participants made choices about whether to exert different levels of physical effort to obtain different magnitudes of reward, or rest for low reward. Prior to each effort-based choice, they also had to decide which information they wanted to see first: how much physical effort would be required, or how large the reward would be. We found no overall preference for seeking reward or effort information first, but motivation did change when people saw reward or effort information first. Seeking effort information first, both someone's average tendency to do so and their choice to see effort first on a given trial, was associated with reductions in the willingness to exert higher effort. Moreover, the tendency to prefer effort information first was associated with reduced vigorous exercise and higher levels of fatigue in everyday life. These findings highlight that preferences for seeking effort information may be a bias that reduces people's willingness to exert effort in the lab and in everyday life.

Placebo Analgesia Reduces Costly Prosocial Helping to Lower Another Person's Pain

Painkiller administration lowers pain empathy, but whether this also reduces prosocial behavior is unknown. In this preregistered study, we investigated whether inducing analgesia through a placebo painkiller reduced effortful helping. When given the opportunity to reduce the pain of another person, individuals experiencing placebo analgesia (n = 45 adults from Austria; 21 male, 24 female) made fewer prosocial choices at the lowest helping level and exerted less physical effort when helping, compared with controls whose pain sensitivity was unaltered (n = 45; 21 male, 24 female). Self-reported empathic unpleasantness positively correlated with prosocial choices across the whole sample. While not replicating group differences in empathy, a mediation analysis revealed that the level of unpleasantness to other people's pain fully mediated the effect of placebo analgesia on prosocial choices. Given the importance of prosociality for social cohesion, these findings have broad potential implications both for individuals under the influence of painkillers and for society at large.

Distinct neural representations for prosocial and self-benefiting effort

Prosocial behaviors-actions that benefit others-are central to individual and societal well-being. Although the mechanisms underlying the financial and moral costs of prosocial behaviors are increasingly understood, this work has often ignored a key influence on behavior: effort. Many prosocial acts are effortful, and people are averse to the costs of exerting them. However, how the brain encodes effort costs when actions benefit others is unknown. During fMRI, participants completed a decision-making task where they chose in each trial whether to "work" and exert force (30%-70% of maximum grip strength) or "rest" (no effort) for rewards (2-10 credits). Crucially, on separate trials, they made these decisions either to benefit another person or themselves. We used a combination of multivariate representational similarity analysis and model-based univariate analysis to reveal how the costs of prosocial and self-benefiting efforts are processed. Strikingly, we identified a unique neural signature of effort in the anterior cingulate gyrus (ACCg) for prosocial acts, both when choosing to help others and when exerting force to benefit them. This pattern was absent for self-benefiting behaviors. Moreover, stronger, specific representations of prosocial effort in the ACCg were linked to higher levels of empathy and higher subsequent exerted force to benefit others. In contrast, the ventral tegmental area and ventral insula represented value preferentially when choosing for oneself and not for prosocial acts. These findings advance our understanding of the neural mechanisms of prosocial behavior, highlighting the critical role that effort has in the brain circuits that guide helping others.

Cognitive effort for self, strangers, and charities

Effort is aversive and often avoided, even when earning benefits for oneself. Yet, people sometimes work hard for others. How do people decide who is worth their effort? Prior work shows people avoid physical effort for strangers relative to themselves, but invest more physical effort for charity. Here, we find that people avoid cognitive effort for others relative to themselves, even when the cause is a personally meaningful charity. In two studies, participants repeatedly decided whether to invest cognitive effort to gain financial rewards for themselves and others. In Study 1, participants (N = 51; 150 choices) were less willing to invest cognitive effort for a charity than themselves. In Study 2, participants (N = 47; 225 choices) were more willing to work cognitively for a charity than an intragroup stranger, but again preferred cognitive exertion that benefited themselves. Computational modeling suggests that, unlike prior physical effort findings, cognitive effort discounted the subjective value of rewards linearly. Exploratory machine learning analyses suggest that people who represented others more similarly to themselves were more willing to invest effort on their behalf, opening up new avenues for future research.

Investigating adult age differences in real-life empathy, prosociality, and well-being using experience sampling

While the importance of social affect and cognition is indisputable throughout the adult lifespan, findings of how empathy and prosociality develop and interact across adulthood are mixed and real-life data are scarce. Research using ecological momentary assessment recently demonstrated that adults commonly experience empathy in daily life. Furthermore, experiencing empathy was linked to higher prosocial behavior and subjective well-being. However, to date, it is not clear whether there are adult age differences in daily empathy and daily prosociality and whether age moderates the relationship between empathy and prosociality across adulthood. Here we analyzed experience-sampling data collected from participants across the adult lifespan to study age effects on empathy, prosocial behavior, and well-being under real-life circumstances. Linear and quadratic age effects were found for the experience of empathy, with increased empathy across the three younger age groups (18 to 45 years) and a slight decrease in the oldest group (55 years and older). Neither prosocial behavior nor well-being showed significant age-related differences. We discuss these findings with respect to (partially discrepant) results derived from lab-based and traditional survey studies. We conclude that studies linking in-lab experiments with real-life experience-sampling may be a promising venue for future lifespan studies.

Emotional Intelligence as a Predictor of Prosocial Behaviors in Spanish and Colombian Older Adults Based on Path Models

Emotional intelligence (EI), empathy, and prosocial behavior (PB) are widely studied in the early stages of life, up to adolescence. However, there have been few studies in older adults. Using a multivariate methodology, exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were applied with structural equation models (SEM) in 271 older adults in Colombia, along with a Spanish sample made up of 139 adults over 60 years of age, for a total sample of 411 older adults. The results confirmed that EI, as measured with the WLEIS, scale is the best predictor of PB, with excellent adjustment criteria (GFI = 0.99; CFI = 0.98; RMSEA = 0.064; PCLOSE = 0.28; SRMR = 0.023; AIC = 57.30). It is concluded that the path model yielded a reliable predictive explanation of PB, including EI as a key variable that explains prosocial tendencies.

Sleep Restriction Reduces Cognitive but Not Physical Motivation

PURPOSE

Motivation is an important driver of behaviour, and several frameworks distinguish the willingness of individuals to invest cognitive versus physical effort to achieve a goal. One outstanding question is whether sleep loss lowers motivation within specific domains of effort, or has a global effect on motivation across multiple domains. Here, we investigated the effects of sleep restriction on the motivation to invest cognitive or physical effort in return for reward.

MATERIALS AND METHODS

24 healthy young adults (11 females) completed an effort-based decision-making task over two laboratory sessions - once while sleep restricted (three consecutive nights with a three-hour sleep opportunity), and the other while fully rested (nine-hour sleep opportunity on each night). In an initial reinforcement phase, participants were trained to ceiling performance across six levels of effort on separate cognitively and physically demanding tasks. Then, in the critical decision-making phase, participants revealed their preference for how much cognitive or physical effort they would be willing to invest for reward.

RESULTS

Sleep restriction reduced the willingness to exert cognitive effort, but spared motivation in the physical domain. Furthermore, the reduction in cognitive motivation appeared to be a primary motivational deficit, which could not be attributed to differences in reward-likelihood of different levels of effort or the temporal structure of the task.

CONCLUSION

The results suggest that sleep restriction has a selective effect on cognitive over physical motivation, which has significant implications for real-world settings in which individuals must maintain high levels of cognitive motivation in the face of chronic sleep loss.

Altered motivation of effortful decision-making for self and others in subthreshold depression

BACKGROUND

Amotivation is a typical feature in major depressive disorders and refers to individuals exhibiting reduced willingness to exert effort for rewards. However, the motivation pattern when deciding whether to exert effort for self versus others in people with depression remains unclear.

METHODS

We conducted a functional magnetic resonance imaging study and employed an adapted Effort-Expenditure for Rewards Task in subthreshold depressive (SD) participants (n = 33) and healthy controls (HC) (n = 32). This required participants to choose between a fixed low-effort/low-reward and a variable high-effort/high-reward option, and then immediately exert effort to obtain corresponding rewards for themselves or for unfamiliar people.

RESULTS

Compared with the HC group, the SD group showed blunted activity in the left dorsal anterior cingulate cortex/dorsomedial prefrontal cortex, bilateral anterior insula (AI), and right putamen-left dorsolateral prefrontal cortex functional connectivity when choosing to exert effort for themselves. Additionally, the SD group exhibited increased willingness and greater activation in the bilateral AI when choosing to exert effort for others. Furthermore, these brain activations and functional connectivity were positively related to self-reported motivation.

CONCLUSIONS

These findings show altered motivation during effort-based decision-making in individuals with the mild depressive state, particularly with higher motivation for others. Thus, this suggests that motivational behaviors and prefrontal-striatal circuitry are altered in individuals with SD, which can be utilized to discover treatment targets and develop strategies to address mental illness caused by motivation disorders.

Heightened effort discounting is a common feature of both apathy and fatigue

Apathy and fatigue have distinct aetiologies, yet can manifest in phenotypically similar ways. In particular, each can give rise to diminished goal-directed behaviour, which is often cited as a key characteristic of both traits. An important issue therefore is whether currently available approaches are capable of distinguishing between them. Here, we examined the relationship between commonly administered inventories of apathy and fatigue, and a measure of goal-directed activity that assesses the motivation to engage in effortful behaviour. 103 healthy adults completed self-report inventories on apathy (the Dimensional Apathy Scale), and fatigue (the Multidimensional Fatigue Inventory, and/or Modified Fatigue Impact Scale). In addition, all participants performed an effort discounting task, in which they made choices about their willingness to engage in physically effortful activity. Importantly, self-report ratings of apathy and fatigue were strongly correlated, suggesting that these inventories were insensitive to the fundamental differences between the two traits. Furthermore, greater effort discounting was strongly associated with higher ratings across all inventories, suggesting that a common feature of both traits is a lower motivation to engage in effortful behaviour. These results have significant implications for the assessment of both apathy and fatigue, particularly in clinical groups in which they commonly co-exist.

Older adults across the globe exhibit increased prosocial behavior but also greater in-group preferences

Population aging is a global phenomenon with substantial implications across society1,2. Prosocial behaviors-actions that benefit others-promote mental and physical health across the lifespan3,4 and can save lives during the COVID-19 pandemic. We examined whether age predicts prosociality in a preregistered global study (46,576 people aged 18-99 across 67 countries) using two acutely relevant measures: distancing during COVID-19 and willingness to donate to hypothetical charities. Age positively predicted prosociality on both measures, with increased distancing and donations among older adults. However, older adults were more in-group focused than younger adults in choosing who to help, making larger donations to national over international charities and reporting increased in-group preferences. In-group preferences helped explain greater national over international donations. Results were robust to several control analyses and internal replication. Our findings have vital implications for predicting the social and economic impacts of aging populations, increasing compliance with public health measures and encouraging charitable donations.

Reconciling Psychological and Neuroscientific Accounts of Reduced Motivation in Aging

Motivation is a hallmark of healthy aging, but the motivation to engage in effortful behavior diminishes with increasing age. Most neurobiological accounts of altered motivation in older adults assume that these deficits are caused by a gradual decline in brain tissue, while some psychological theories posit a switch from gain orientation to loss avoidance in motivational goals. Here, we contribute to reconcile the psychological and neural perspectives by providing evidence that the frontopolar cortex (FPC), a brain region involved in cost–benefit weighting, increasingly underpins effort avoidance rather than engagement with age. Using anodal transcranial direct current stimulation together with effort–reward trade-offs, we find that the FPC’s function in effort-based decisions remains focused on cost–benefit calculations but appears to switch from reward-seeking to cost avoidance with increasing age. This is further evidenced by the exploratory, independent analysis of structural brain changes, showing that the relationship between the density of the frontopolar neural tissue and the willingness to exert effort differs in young vs older adults. Our results inform aging-related models of decision-making by providing preliminary evidence that, in addition to cortical thinning, changes in goal orientation need to be considered in order to understand alterations in decision-making over the life span.

Ageing is associated with disrupted reinforcement learning whilst learning to help others is preserved

Reinforcement learning is a fundamental mechanism displayed by many species. However, adaptive behaviour depends not only on learning about actions and outcomes that affect ourselves, but also those that affect others. Using computational reinforcement learning models, we tested whether young (age 18-36) and older (age 60-80, total n = 152) adults learn to gain rewards for themselves, another person (prosocial), or neither individual (control). Detailed model comparison showed that a model with separate learning rates for each recipient best explained behaviour. Young adults learned faster when their actions benefitted themselves, compared to others. Compared to young adults, older adults showed reduced self-relevant learning rates but preserved prosocial learning. Moreover, levels of subclinical self-reported psychopathic traits (including lack of concern for others) were lower in older adults and the core affective-interpersonal component of this measure negatively correlated with prosocial learning. These findings suggest learning to benefit others is preserved across the lifespan with implications for reinforcement learning and theories of healthy ageing.