Brain regions exhibit dynamic yet highly coordinated activity patterns that form large-scale functional networks measurable through resting-state correlations. While their association with fluctuating activity may intuitively suggest functional networks to be temporally transient and dependent on state, a growing body of literature suggests that they are person-specific and stable across days. If truly person-specific, then functional networks should preserve unique characteristics over extended periods. To test this hypothesis, we collected longitudinal precision fMRI data (≥60 minutes per participant per time point) from 10 healthy young adults across 1-3 year intervals, as well as three adults over 8-13 years. We further replicated findings in the MyConnectome dataset and its 10-year follow-up. Functional network organization-when sufficient per-participant data were collected- remained largely stable within individuals over prolonged periods of up to 13 years, suggesting that individualized brain organization constitutes persistent features of personal identity that may be supported by homeostatic mechanisms.

Valence is a common feature across emotion theories and is often described using a simple positive versus negative dimension. Whereas many circumstances elicit relatively consistent categorizations of positivity and negativity across people, there are other conditions when the valence of a stimulus is ambiguous and thus defies this simple, uniform categorization. In this short review, we will describe research investigating individual differences in interpretations of valence ambiguity to support the notion that valence is not an invariant feature of a stimulus, but rather arises from diverse appraisals that can be learned, challenged, and changed. These individual differences are referred to as valence or interpretation biases and defined as the tendency to evaluate ambiguous emotional stimuli as more positive or negative. Valence bias has been associated with affective traits, psychosocial functioning, and brain organization, demonstrating trait-like stability that, nonetheless, is malleable during targeted interventions including treatment for mental health disorders. Collectively, studies of valence ambiguity highlight the variable nature of valence interpretations across people, supporting the notion that valence itself is a multifaceted construct uniquely determined by the perceiver in a given context. Future research should further probe valence ambiguity in real world conditions and better characterize individual differences in the origins, limits, and implications of biased valence interpretations.

An extensive body of research on human and nonhuman animals has examined responses to clear valence, including stimuli that either represent a relatively clear threat (e.g., electric shock) or a clear reward (e.g., money). But daily life is replete with events or situations that are ambiguous-they could be threatening and/or rewarding. This article describes work that examines the wide interindividual variability with which humans respond to this dual-valence ambiguity. Although some individuals more readily categorize these events as negative, others are prone to arrive at more positive categorizations. This predilection to lean in a more negative versus positive direction represents a stable, trait-like difference and is referred to as "valence bias." Valence bias is generalizable across categories of dual-valence ambiguity and has important implications for health and well-being. Here I focus on extensive findings that lend support for the initial negativity hypothesis, which posits that the initial or default response is negative across people and that positivity relies on an additional regulatory mechanism that helps to overcome the initial negativity. I also describe the cognitive and brain mechanisms underlying the valence bias, including emphasizing the importance of a broad set of systems that support human responses to ambiguity.

BackgroundIndividuals vary in their tendency to interpret emotionally ambiguous stimuli as relatively more positive or negative, a trait-like difference known as “valence bias.” To date, research on valence bias has relied upon two-alternative forced-choice (2AFC) valence decisions that conflate the presence of positivity with the absence of negativity, and vice versa. This is problematic because more frequent negative judgments of ambiguous stimuli (i.e., a more negative valence bias) could represent true negative appraisals of those stimuli, or a difficulty in identifying a positive appraisal.MethodsIn two preregistered studies, participants completed a standard 2AFC valence bias task (n = 100 and n = 508 in the respective studies) and provided separate positive and negative unipolar ratings of the same stimuli.ResultsThe 2AFC valence bias task captured independent effects of both positivity and negativity. Individuals with a more negative valence bias showed high endorsement of negativity and low endorsement of positivity; those with a more positive bias showed the opposite pattern. Individuals with a more positive valence bias also exhibited a stronger relationship between positive unipolar ratings and 2AFC categorization than individuals with a more negative valence bias, suggesting a greater sensitivity to positive appraisals. These results replicated in Study 2 in a larger, more diverse sample using unique stimulus sets.DiscussionDespite individual differences as a function of valence bias, ambiguous stimuli were endorsed as both positive and negative on unipolar scales, refuting claims that they might be “valence-free.” Collectively, these results demonstrated that multiple appraisals of ambiguity are recognized and weighted based on individual bias in valence processing during affective decision-making.

Obesity is a growing public health concern with more than 40% of adults meeting criteria for obesity in the United States. Although many treatments seek to lower individual's weight, few treatments have focused on cognitive strategies to change the way individuals think about food, therefore, decreasing consumption of non-nutrient-dense foods. Cognitive reappraisal is one strategy that involves changing the way one thinks about a situation and can be used to downregulate responses to those stimuli. Leveraging this intuitive, cost-effective strategy to decrease one's desire to eat unhealthy food and therefore, decrease overeating, could improve physical and mental health. The present study identified brain regions that are differentially activated when using cognitive reappraisal to downregulate responses to food (FR) versus when using the same strategy to downregulate negative emotions (ER). We collected functional magnetic resonance imaging (fMRI) data in 63 undergraduate students while participants completed both tasks. There was increased reappraisal-related activation in widespread regions across both tasks, including in expected subcortical (i.e., striatum) and cortical areas (i.e., visual, frontoparietal). We also found domain-specific activity, with greater insula activation in the FR than the ER task and greater hippocampal activation in the ER than the FR task. These results reveal domain-general and domain-specific effects of cognitive reappraisal in FR and ER tasks that inform future work examining eating behavior. Taken together, a better explication of the overlapping and discrete processes of food regulation, as it compares to other applications of this regulatory strategy can inform new intervention targets.

Having strong, diverse social relationships is tightly linked to myriad physical and mental health benefits by mitigating the negative impacts of adverse events. The COVID-19 pandemic brought increased uncertainty and changes to our social lives that reduce the spread of COVID-19 (e.g., social distancing), but also likely impacted emotional well-being. We investigated how one of these changes – changing social networks – relates to emotional bias (a proxy for well-being), specifically one’s tendency to interpret ambiguous stimuli as positive or negative (i.e., valence bias). Participants (N = 614) categorized the valence of clearly (angry and happy expressions) and ambiguously valenced stimuli (surprised expressions), and were asked about their social network before and during the pandemic. Compared to before the pandemic, participants reported a decrease in overall network size (p < .001) and number of embedded networks (i.e., a measure of network complexity represented by number of areas of social activity; p < .001). In a model with all three social network dimensions (size, complexity, diversity), network complexity uniquely predicted valence bias (p = .02). Specifically, participants with greater social network complexity during the pandemic showed a more positive bias. Further, participants that did not experience a pandemic-related reduction in network complexity were protected from pandemic-related increases in negativity (p < .001). In other words, having a more complex social network could act as a protective factor against adverse outcomes in times of uncertainty.

There are individual differences in how people respond to emotionally ambiguous cues (i.e., valence bias), which have important consequences for mental health, development, and social functioning, yet how these differences develop in childhood and adolescence is unknown. Extensive literature shows that children's cognitive biases, including appraisals in uncertain situations, can be influenced by parents. The current study collected valence bias from parent and child dyads (n = 136, children ages 6-17 years, M = 10.92, SD = 3.22) using a dual-valence ambiguity task (i.e., the valence bias task). Using structural equation modeling, we found that a child's valence bias was associated with their parent's valence bias (β = 0.283, p = 0.005). We also explored the effect of parent-child attachment in three facets (communication, alienation, and trust) on this intergenerational transmission. Communication moderated the relationship between parent and child valence bias, such that higher communication led to a stronger relationship between parent and child valence bias (β = 0.03, p = 0.04). These findings suggest that one mechanism that supports valence bias development is the parent's bias, and this may be uniquely influenced by the degree of parent-child communication. This tendency to similarly interpret ambiguous stimuli may result from social learning. Specifically, our results support a theory of generalized shared reality where parents and children who have a greater interpersonal connection (i.e., communication) also share a more similar world view (i.e., valence bias). A video abstract of this article can be viewed at https://www.youtube.com/watch?v=xlSDxFDmP7g SUMMARY: Valence bias represents variability in appraisals of emotional ambiguity, with some people showing greater negativity, and others more positive. There is evidence of intergenerational transmission of valence bias, such that children tend to have a bias that mirrors their parents. Transmission was moderated by parent-child attachment, such that children that report greater communication with their parent show a more similar bias to their parent. These findings are discussed in the context of theories on development and generalized shared realities.

The long-term consequences of concussion are still being uncovered but have been linked to disruptions in cognition and psychological well-being. Previous studies focusing on the association between concussion history and structural changes in the brain have reported inconsistent results. We sought to examine the effect of concussion history on cortical volume with a focus on functional networks. These networks are associated with many of the functions that can be disrupted in those with an extensive concussion history. We collected baseline behavioral data including the Immediate Post-Concussion Assessment and Cognitive Testing, a self-report measure of the number of diagnosed concussions, and structural MRI in college athletes (n=296; 263 men and 33 women, age range 17-24). Behavioral measures were collected by members of the Department of Athletics concussion management team using a standardized protocol as part of their on-boarding process. Collegiate athletes in the present study who self-reported concussion history did not report different baseline symptoms and did not exhibit consistent differences in cognitive performance relative to those who reported no concussion history. We found that concussion history was not related to cortical volume at the network or region level, even when we compared participants with two or more concussions to those with no concussion history. We did identify relationships between cortical volume in the visual network and dorsal attention network with cognitive performance. In addition to comparing cortical volume between individuals with and without reported concussion history, we also examined whether cortical volume changes could be observed within individuals from baseline to acutely following concussion. We found that network level cortical volume did not change within subjects from baseline measurement to acutely post-concussion. Together, these results suggest that both self-reported concussion history and acute concussion effects are not associated with changes in cortical volume in young adult athletes.

Cognitive reappraisal is a fundamental emotion regulation strategy for mental and physical well-being, but how its neural mechanisms relate to individual differences remains poorly understood. In a consortium effort analyzing 40 fMRI datasets ( N =2,175), we examined the relationship between neural activation during reappraisal tasks and three core individual difference indices of reappraisal capabilities: (1) trait questionnaires, (2) task-based affective ratings, and (3) amygdala down-regulation. Strikingly, there was no shared overlap across these three common indices. Only a very weak correlation emerged between amygdala down-regulation and task-based affective ratings. Whole-brain analyses revealed no reliable neural associations with trait questionnaires, and associations with task-based affective ratings fell outside canonical emotion regulation networks (e.g., prefrontal circuitry). Moreover, amygdala down-regulation, often interpreted as a stable individual marker, was confounded by person-specific whole-brain responses — a limitation extending to fMRI research beyond the emotion regulation domain. These findings challenge the assumption that an individual’s prefrontal activity is a valid indicator of their reappraisal capabilities and suggest that common trait, behavioral, and neural measures might capture distinct facets of emotion regulation. More broadly, our results highlight concrete methodological challenges for fMRI research on individual differences, with implications extending beyond emotion regulation to the neuroscience of personality, psychopathology, and general well-being. ### Competing Interest Statement The authors have declared no competing interest.

Emotional expressions offer important social cues about the expresser’s intentions and risks or rewards in the environment. The current study investigated how individual differences in interpretation of ambiguous facial expressions (valence bias) are impacted by intergroup racial biases. In an online study of 409 racially diverse US participants, we found that across racial groups, participants judged in-group faces more positively than out-group faces regardless of expression (happy, angry, or surprised). Furthermore, valence bias generalized from a set of all-White faces to a set of racially diverse faces (Asian, Black, Hispanic, and White). Within the latter task, valence judgments differed as a function of stimulus model race, with more negative judgments of Asian and Black surprised faces. Thus, both individual valence bias and intergroup racial bias influenced emotion judgments, suggesting that these biases intersect in shaping social perceptions and decision-making.

Both emotion regulation and physical activity are associated with improved emotional well-being, including high self-esteem. However, most prior work comparing this relationship is limited by either subjective bias or ecological validity. Using objective (i.e., accelerometer-derived) measures of physical activity, this study investigated the relationship between moderate-to-vigorous physical activity (MVPA) and two trait emotion regulation strategies. We predicted that trait reappraisal (i.e., the habitual use of cognitive reappraisal to regulate emotions in daily life), but not trait suppression (i.e., the habitual use of expressive suppression to regulate emotions in daily life), would be associated with higher engagement in MVPA. We also predicted that physical activity would buffer reliance on trait reappraisal, such that individuals who engaged in more MVPA would be less likely to report emotion regulation difficulties or low self-esteem. Participants (N = 251 adults, ages 17–88 years) filled out questionnaires assessing trait emotion regulation, emotion regulation difficulties, and self-esteem, and wore an ActiGraph® on their non-dominant wrist for one week (M(SD) = 7.46(2.32) days). Regression and moderation analyses were conducted on variables of interest. Neither trait reappraisal nor suppression were associated with MVPA. MVPA significantly moderated the negative relationship between trait reappraisal and emotion regulation difficulties, such that the relationship was stronger at lower levels of MVPA. Effects were not found with self-esteem or trait suppression. These results indicate that MVPA may be beneficial in maintaining emotional well-being, particularly in the face of emotion regulation difficulties.

Heightened reactivity to ambiguous emotional stimuli, such as surprized faces, is a transdiagnostic psychopathology risk factor. Women show elevated amygdala activation to ambiguous emotional stimuli relative to men, which may underlie their significantly higher risk for mood disorders. Moreover, there are sex/gender differences in the effects of stress on both emotion processing and emotion regulation, with greater impact of stress on negative emotionality in females. We predicted that chronic stress would be associated with stronger amygdala activation to surprized faces, and these effects would be amplified in girls/women. We tested the interactions of chronic stress and gender/sex on amygdala activity in a sample of 297 healthy participants (59% girls/women, age range 6-75 years) who provided a saliva sample and who viewed emotional face stimuli while undergoing functional neuroimaging. Saliva samples were assayed for two markers of chronic stress: Epstein-Barr Virus (EBV) expression and diversity of Lactobacilli species. Among girls/women, higher chronic stress was associated with greater amygdala activation to ambiguous emotional images than lower stress exposure, although this effect was not statistically significant. Counter to predictions, the reverse effect was found among boys/men (i.e., higher stress exposure was associated with lower amygdala activation). Results were similar across left and right amygdalae, and across both stress measures. Although our findings are preliminary and should be replicated, they align with findings on gender differences in valence bias, and broadly support the hypothesis that there are gender/sex differences in the effects of chronic stress on neural reactivity to emotional ambiguity, particularly in areas of the brain sensitive to emotion regulation. Possibly, stress does not universally increase negativity, but instead amplifies default emotional biases-which for boys/men, may result in less amygdala reactivity.

Semantic priming has been studied for nearly 50 years across various experimental manipulations and theoretical frameworks. Although previous studies provide insight into the cognitive underpinnings of semantic representations, they have suffered from small sample sizes and a lack of linguistic and cultural diversity. In this Registered Report, we measured the size and the variability of the semantic priming effect across 19 languages (N = 25,163 participants analyzed) by creating the largest available database of semantic priming values based on an adaptive sampling procedure. We found evidence for semantic priming in terms of differences in response latencies between related word-pair conditions and unrelated word-pair conditions. Model comparisons showed that inclusion of a random intercept for language improved model fit, providing support for variability in semantic priming across languages. This study highlights the robustness and variability of semantic priming across languages and provides a rich, linguistically diverse dataset for further analysis.

Cognitive reappraisal is a form of emotion regulation that involves the reinterpretation of stimuli to change one’s emotional state, often to reduce negative affect. Emotion regulation fMRI tasks generally yield increased activation in prefrontal cortex and, less consistently, decreased amygdala activation. Only a few studies, however, have examined how intrinsic brain organization, characterized via resting-state fMRI, relates to reappraisal, typically focusing on the same task-derived brain regions. Here, we administered an emotion regulation task where participants (n = 227, 6-80 years) viewed or downregulated responses to negative images, then completed a resting-state fMRI scan. We examined the functional connectivity in 300 whole-brain regions of interest comprising 13 functional networks. We found that the network segregation, or relative balance of within- and between-network connectivity, in the default mode (DMN), dorsal attention (DAN), and dorsal somatomotor (SMd) networks was associated with reappraisal success (controlling for age and movement). Specifically, greater connectivity within the DMN and DAN, lower connectivity within the SMd, and greater connectivity between the SMd and lateral SM networks predicted better reappraisal ability. These networks also partially overlapped with brain areas supporting emotion regulation and reactivity, suggesting that functional brain organization is a key factor in shaping emotion regulation across the lifespan.