Shared neural mechanisms underlying social warmth and physical warmth

Emerging effects of temperature on human cognition, affect, and behaviour

Human body core temperature is tightly regulated within approximately 37 °C. Global near surface temperature has increased by over 1.2 °C between 1850 and 2020. In light of the challenge this poses to human thermoregulation, the present perspective article sought to provide an overview on the effects of varying ambient and body temperature on cognitive, affective, and behavioural domains of functioning. To this end, an overview of observational and experimental studies in healthy individuals and individuals with mental disorders was provided. Within body core temperature at approximately 37 °C, relatively lower ambient and skin temperatures appear to evoke a need for social connection, whereas comparably higher temperatures appear to facilitate notions of other as closer and more sociable. Above-average ambient temperatures are associated with increased conflicts as well as incident psychotic and depressive symptoms, mental disorders, and suicide. With mild hypo- and hyperthermia, paradoxical effects are observed: whereas the acute states are generally characterised by impairments in cognitive performance, anxiety, and irritability, individuals with depression experience longer-term symptom improvements with treatments deliberately inducing these states for brief amounts of time. When taken together, it has thus become clear that temperature is inexorably associated with human cognition, affect, and (potentially) behaviour. Given the projected increase in global warming, further research into the affective and behavioural sequelae of heat and the mechanisms translating it into mental health outcomes is urgently warranted.

Influences of Indoor Air Temperatures on Empathy and Positive Affect

The consequences of climate change are already visible, and yet, its effect on psychosocial factors, including the expression of empathy, affect, and social disconnection, is widely unknown. Outdoor conditions are expected to influence indoor conditions. Therefore, the aim of this study was to investigate the effect of indoor air temperature during work hours on empathy, positive and negative affect, and social disconnection. Participants (N = 31) were exposed, in a cross-over design, to two thermal conditions in a simulated office environment. Questions on empathy and social disconnection were administered before and after the exposure to each condition, while affect was measured throughout the day. Subjective thermal sensation and objective measures of mean skin temperature were considered. The results indicated a significant difference in empathy (F(1, 24) = 5.37, p = 0.03, with an η2 = 0.126) between conditions. Participants reported increases in empathy after exposure to the warm condition compared to the cool condition, in which reductions in empathy were reported. Although the same pattern was observed for positive affect, the difference was smaller and the results were not significant. Thermal sensation had a significant effect on changes in empathy too (F(1, 54) = 7.015, p = 0.01, with an R2 = 0.115), while mean skin temperature had no effect on empathy (F(1, 6) = 0.53, p = 0.89, with an R2 = 0.81). No effects were observed for positive and negative affect and social disconnection. Longitudinal studies are needed to support these findings.

Depth and hierarchies in the predictive brain: From reaction to action

The human brain is a prediction device, a view widely accepted in neuroscience. Prediction is a rational and efficient response that relies on the brain's ability to create and employ generative models to optimize actions over unpredictable time horizons. We argue that extant predictive frameworks while compelling, have not explicitly accounted for the following: (a) The brain's generative models must incorporate predictive depth (i.e., rely on degrees of abstraction to enable predictions over different time horizons); (b) The brain's implementation scheme to account for varying predictive depth relies on dynamic predictive hierarchies formed using the brain's functional networks. We show that these hierarchies incorporate the ascending processes (driven by reaction), and the descending processes (related to prediction), eventually driving action. Because they are dynamically formed, predictive hierarchies allow the brain to address predictive challenges in virtually any domain. By way of application, we explain how this framework can be applied to heretofore poorly understood processes of human behavioral thermoregulation. Although mammalian thermoregulation has been closely tied to deep brain structures engaged in autonomic control such as the hypothalamus, this narrow conception does not translate well to humans. In addition to profound differences in evolutionary history, the human brain is bestowed with substantially increased functional complexity (that itself emerged from evolutionary differences). We argue that behavioral thermoregulation in humans is possible because, (a) ascending signals shaped by homeostatic sub-networks, interject with (b) descending signals related to prediction (implemented in interoceptive and executive sub-networks) and action (implemented in executive sub-networks). These sub-networks cumulatively form a predictive hierarchy for human thermoregulation, potentiating a range of viable responses to known and unknown thermoregulatory challenges. We suggest that our proposed extensions to the predictive framework provide a set of generalizable principles that can further illuminate the many facets of the predictive brain. This article is categorized under: Neuroscience > Behavior Philosophy > Action Psychology > Prediction.

The physiological study of emotional piloerection: A systematic review and guide for future research

This paper provides an accessible review of the biological and psychological evidence to guide new and experienced researchers in the study of emotional piloerection in humans. A limited number of studies have attempted to examine the physiological and emotional correlates of piloerection in humans. However, no review has attempted to collate this evidence to guide the field as it moves forward. We first discuss the mechanisms and function of non-emotional and emotional piloerection in humans and animals. We discuss the biological foundations of piloerection as a means to understand the similarities and differences between emotional and non-emotional piloerection. We then present a systematic qualitative review (k = 24) in which we examine the physiological correlates of emotional piloerection. The analysis revealed that indices of sympathetic activation are abundant, suggesting emotional piloerection occurs with increased (phasic) skin conductance and heart rate. Measures of parasympathetic activation are lacking and no definite conclusions can be drawn. Additionally, several studies examined self-reported emotional correlates, and these correlates are discussed in light of several possible theoretical explanations for emotional piloerection. Finally, we provide an overview of the methodological possibilities available for the study of piloerection and we highlight some pressing questions researchers may wish to answer in future studies.

Exploring the effect of loneliness on fear: Implications for the effect of COVID-19-induced social disconnection on anxiety

The consequences of the COVID-19 pandemic have resulted in many disruptions to daily life, including an abrupt increase in social disconnection. As measures were put in place to combat the spread of COVID-19, people across the globe began living in states of limited social contact, fostering feelings of social isolation and loneliness. Previous literature suggests that these increases in social disconnection can have profound effects on both physical and mental health, perhaps especially in the case of fear disorders. The combination of feeling disconnected from others and the high level of daily threat experienced due to COVID-19 created conditions under which dysfunctional and persistent fears were especially likely to develop. Building on current understanding of the harmful effects of social disconnection on well-being in general as well as specific implications for fear, here we present findings from three preliminary investigations that are the first to directly examine the effects of loneliness on how fears are learned and maintained. The Results of this work show that loneliness impairs the process by which fears are extinguished, which is central to both the regulation of fear and treatment of fear disorders, and provide insight into potential avenues to mitigate such effects.

Sensory Stimuli to Sustainable Social Wellbeing: A Multimodal Approach Based on Warm Scent

Sensory experiences affect individuals’ judgment and behavior through the metaphors that experiences carry. The literature has demonstrated that the perception of warmth activates concepts related to positive meaning and metaphors, such as consideration and gentleness, which increase individuals’ tendency to help or relate to others. This study hypothesized that warm olfactory stimuli influence intention toward prosocial behavior by increasing the need for social connectedness (NSC). The first experiment (n = 123) demonstrated that the actual warm scent increased participants’ intentions for prosocial behavior and that the effect of the actual warm scent was mediated by NSC. Using Amazon Mechanical Turk (MTurk), a second experiment (n = 995) was conducted the showed that warm scent simulated via visual stimuli (i.e., a multimodal approach) led to prosocial behavior intention as well. The results of the study provide academic and managerial insights into how to improve prosocial behavior intention, which is essential for the sustainable development of societies.

Investigating the relative merits of using a mixed reality context for measuring affective response and predicting tea break snack choice

Sensory evaluation for the investigation of food consumption is often conducted in a controlled laboratory environment, which does not reflect consumption behaviour in real world. Here, we compared the effect of consumption setting (traditional sensory booth, mixed reality projection café, and a café) on consumer affective responses, and to investigate the effectiveness of using Microsoft HoloLens technology, an Augmented Mixed Reality device, as an ecologically valid alternative to natural consumption eating for sensory evaluation. Participant [(n = 120): 86 females/34 males, aged 18-65 years] affective response (overall liking, attribute liking, emotional response, and snack choice) towards two commercially available tea break snacks (caramel slice and chocolate digestive biscuit) was assessed in three different consumption settings using a balanced crossover design. There were no significant differences for most affective ratings between data obtained from the HoloLens evoked café and real café (p ≥ 0.10), suggesting that mixed reality could provide an ecologically valid context for consumer research. However, response differences were observed between these two contexts and the sensory booths. For example, interested, joy, enthusiastic emotion terms were rated slightly higher in the evoked café in comparison to the booth context and slightly higher emotional engagement was observed for joy in the café compared to the booths (all p < .10). This study highlights key considerations for deciding where consumer testing should be conducted and the importance of using a combination of overall liking, attribute liking and emotional response to obtain data representative of real-world environments in consumer studies.

Social reward and support effects on exercise experiences and performance: Evidence from parkrun

There is growing academic, civic and policy interest in the public health benefits of community-based exercise events. Shifting the emphasis from competitive sport to communal activity, these events have wide appeal. In addition to physical health benefits, regular participation can reduce social isolation and loneliness through opportunities for social connection. Taking a broad evolutionary and social psychological perspective, we suggest that social factors warrant more attention in current approaches to physical (in)activity and exercise behavior. We develop and test the hypothesis that social reward and support in exercise are associated with positive exercise experiences and greater performance outputs. Using a repeated-measures design, we examine the influence of social perceptions and behavior on subjective enjoyment, energy, fatigue, effort, and objective performance (run times) among a UK sample of parkrun participants. Social factors were associated with greater subjective enjoyment and energy. Higher subjective energy, in turn, was associated with faster run times, without any corresponding increase in perceived effort. No significant main effects of social factors on fatigue, performance or effort were detected. The role of social structural factors has long been recognized in public health approaches to physical activity. Our results indicate that there should be greater research attention on how positive and rewarding social behaviors and experiences-particularly subjective enjoyment and energy, and perceptions of community social support and belonging-influence exercise-related behavior, psychology and physiology, and promote health through collective physical activity. The research also supplements traditional emphases on social facilitation and team sport that have dominated sport and exercise psychology and offers new avenues for understanding the deep connections among psychological, social and physical function in everyday health.

Reminders of COVID-19 social distancing can intensify physical pain

Social distance regulations have been widely implemented to control the global COVID-19 pandemic. Individuals have thus been experiencing social pain through social distance regulations. Prior research has shown that social and physical pains share a common neural alarm system. Hence, COVID-19 social distancing should enhance sensitivity to physical pain. Two laboratory studies were conducted to test the spillover effect of COVID-19 social distancing on physical pain. The findings supported our hypothesis by showing that participants who were reminded of COVID-19 social distancing reported a higher level of pain perception in response to immersion in hot water (Experiment 1, N = 102) and expressed a lower pain threshold measured by a pressure algometer than did those of controls (Experiment 2, N = 140). This may be the first experimental evidence demonstrating that people primed with COVID-19 social distancing have increased sensitivity to physical pain. Our findings suggest that people might be more likely to experience physical pain under the impact of COVID-19 social distancing. The association between a heightened sense of social disconnection in a global pandemic and increased sensitivity to physical pain should receive more attention.

The role of social isolation in opioid addiction

Humans are social animals: social isolation hurts people both psychologically and physically. Strong, positive social bonds help people to live longer and healthier lives compared with their more isolated peers. Opioid use disorder is associated with feelings of social isolation, an increased risk of suicide and, at the community level, lower social capital. I propose a psychobiological mechanistic explanation that contributes to the association between opioid use and social isolation. The endogenous opioid system plays a central role in the formation and maintenance of social bonds across the life span and has been investigated primarily through the framework of the brain opioid theory of social attachment. In primates, maternal-infant bonding and social play are both impaired by the administration of naltrexone (an opioid antagonist), and in humans, the chronic use of opioids appears to be particularly (relative to other drugs) corrosive to close relationships. Social isolation may play a role in the development and exacerbation of opioid use disorder. Taken together, work on the brain’s opioid system suggests a possible mechanistic basis for bidirectional causal links between social isolation and opioid use disorder. Evaluation of this hypothesis would benefit from longitudinal psychosocial and neuropsychopharmacological investigations.

Harnessing Neuroimaging to Reduce Socioeconomic Disparities in Chronic Disease: A Conceptual Framework for Improving Health Messaging

Socioeconomic status (SES)-related health disparities persist for numerous chronic diseases, with lower-SES individuals exhibiting greater risk of morbidity and mortality compared to their higher-SES counterparts. One likely contributor is disparities in health messaging efforts, which are currently less effective for motivating health behavior change among those lower in SES. Drawing on communication neuroscience and social neuroscience research, we describe a conceptual framework to improve health messaging effectiveness in lower SES communities. The framework is based on evidence that health-message-induced activity in the ventral striatum (VS) and subdivisions of the medial pre-frontal cortex (MPFC) predicts behavior change. Additionally, we draw from social neuroscience work showing that activity in these regions during valuation and the processing of self-related vs. social information, differs as a function of SES. Bringing together these previously disparate lines of work, we argue that health messages emphasizing the benefits to close others (vs. the self) of engaging in behavior change will be more effective among lower SES individuals. We also outline a research agenda based on our framework. Ultimately, we hope that this framework utilizing a “brain-as-predictor” approach generates novel insights about the neural underpinnings of message-induced behavior change among lower SES individuals, and helps to close the gap in SES-based health disparities by harnessing the power of neuroimaging.

Structure and function in human and primate social networks: implications for diffusion, network stability and health

The human social world is orders of magnitude smaller than our highly urbanized world might lead us to suppose. In addition, human social networks have a very distinct fractal structure similar to that observed in other primates. In part, this reflects a cognitive constraint, and in part a time constraint, on the capacity for interaction. Structured networks of this kind have a significant effect on the rates of transmission of both disease and information. Because the cognitive mechanism underpinning network structure is based on trust, internal and external threats that undermine trust or constrain interaction inevitably result in the fragmentation and restructuring of networks. In contexts where network sizes are smaller, this is likely to have significant impacts on psychological and physical health risks.

Interactive Effects of Tactile Warmth and Ambient Temperature on the Search for Social Affiliation

Abstract. Laboratory studies have linked variability in temperature to the psychology of social affiliation. In colder ambient environments, for example, people report greater loneliness, and they pursue both physical warmth and social affiliation (i.e., social warmth). Here, a field experiment tested whether tactile warmth eliminates the effect of colder ambient temperatures on desires for social affiliation. Consistent with previous research, people expressed greater intentions to affiliate on colder days. However, tactile warmth eliminated this effect. On colder (but not warmer) days exposure to a tactile warmth manipulation eliminated heightened desires for social affiliation. Findings suggest that seemingly subtle changes in temperature can have important implications for the psychology of social affiliation, and such findings apply to real-world contexts outside the laboratory.

Opioids and social bonding: Effect of naltrexone on feelings of social connection and ventral striatum activity to close others

Close social bonds are critical to immediate and long-term well-being. However, the neurochemical mechanisms by which we remain connected to our closest loved ones are not well understood. Opioids have long been theorized to contribute to social bonding via their actions on the brain. But feelings of social connection toward one's own close others and direct comparisons of ventral striatum (VS) activity in response to close others and strangers, a neural correlate of social bonding, have not been explored. Therefore, the current clinical trial examined whether opioids causally affect neural and experiential signatures of social bonding. Eighty participants were administered naltrexone (n = 40), an opioid antagonist that blocks natural opioid processing, or placebo (n = 40) before completing a functional MRI scan where they viewed images of their close others and individuals they had not seen before (i.e., strangers). Feelings of social connection to the close others and physical symptoms commonly experienced when taking naltrexone were also collected. In support of hypotheses, naltrexone (vs. placebo) reduced feelings of social connection toward the close others (e.g., family, friends, romantic partners). Furthermore, naltrexone (vs. placebo) reduced left VS activity in response to images of the same close others, but did not alter left VS activity to strangers. Finally, the positive correlation between feelings of connection and VS activity to close others present in the placebo condition was erased by naltrexone. Effects remained after adjusting for physical symptoms. Together, results lend support to theories suggesting that opioids contribute to social bonding, especially with our closest loved ones. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Money: An Integrated Review and Synthesis From a Psychological Perspective

Many empirical studies have demonstrated the psychological effects of various aspects of money, including the aspiration for money, mere thoughts about money, possession of money, and placement of people in economic contexts. Although multiple aspects of money and varied methodologies have been focused on and implemented, the underlying mechanisms of the empirical findings from these seemingly isolated areas significantly overlap. In this article, we operationalize money as a broad concept and take a novel approach by providing an integrated review of the literature and identifying five major streams of mechanisms: (a) self-focused behavior; (b) inhibited other-oriented behavior; (c) favoring of a self–other distinction; (d) money’s relationship with self-esteem and self-efficacy; and (e) goal pursuit, objectification, outcome maximization, and unethicality. Moreover, we propose a unified psychological perspective for the future—money as an embodiment of social distinction—which could potentially account for past findings and generate future work.

Intergenerational mentoring, eudaimonic well-being and gene regulation in older adults: A pilot study

To clarify the biological mechanisms underlying the relationship between pro-social behavior and health, this pilot study examined the impact of a 9-month intergenerational helping intervention on conserved transcriptional response to adversity (CTRA) gene expression profiles, which are characterized by up-regulation of genes involved in inflammation and down-regulation of genes involved in antiviral defenses. The Generation Xchange program trains and places older (age 50+) volunteers in K-3^rd grade classrooms to aid students' academic development (reading and math) and address behavioral issues (e.g., inability to focus during class, behaviors that disrupt class). Volunteers were predominately women (89%) and African American (94%) from the neighborhoods around the schools. Repeated measures planned contrast analysis of 53 CTRA indicator transcripts in 50 blood samples collected from 18 individuals on 2-3 occasions revealed a significant reduction in CTRA gene expression from baseline to the average of 3- and 9-month follow-up. The magnitude of individual decrease in CTRA gene expression correlated with the magnitude of individual increase in eudaimonic well-being over time (net of changes in hedonic well-being). In addition to clarifying biological pathways through which pro-social behavior might impact health, these pilot data suggest that the GenX program may have favorable effects on immune cell gene regulation.

Distinct varieties of aesthetic chills in response to multimedia

The experience of aesthetic chills, often defined as a subjective response accompanied by goosebumps, shivers and tingling sensations, is a phenomenon often utilized to indicate moments of peak pleasure and emotional arousal in psychological research. However, little is currently understood about how to conceptualize the experience, particularly in terms of whether chills are general markers of intense pleasure and emotion, or instead a collection of distinct phenomenological experiences. To address this, a web-study was designed using images, videos, music videos, texts and music excerpts (from both an online forum dedicated to chills-eliciting stimuli and previous musical chills study), to explore variations across chills experience in terms of bodily and emotional responses reported. Results suggest that across participants (N = 179), three distinct chills categories could be identified: warm chills (chills co-occurring with smiling, warmth, feeling relaxed, stimulated and happy), cold chills (chills co-occurring with frowning, cold, sadness and anger), and moving chills (chills co-occurring with tears, feeling a lump in the throat, emotional intensity, and feelings of affection, tenderness and being moved). Warm chills were linked to stimuli expressing social communion and love; cold chills were elicited by stimuli portraying entities in distress, and support from one to another; moving chills were elicited by most stimuli, but their incidence were also predicted by ratings of trait empathy. Findings are discussed in terms of being moved, the importance of differing induction mechanisms such as shared experience and empathic concern, and the implications of distinct chills categories for both individual differences and inconsistencies in the existing aesthetic chills literature.

Naltrexone alters responses to social and physical warmth: implications for social bonding

Socially warm experiences, when one feels connected to others, have been linked with physical warmth. Opioids, hypothesized to support social bonding with close others and, separately, physical warmth, may underlie both experiences. In order to test this hypothesis, 80 participants were randomly assigned to the opioid antagonist, naltrexone or placebo before neural and emotional responses to social and physical warmth were collected. Social and physical warmth led to similar increases in ventral striatum (VS) and middle-insula (MI) activity. Further, feelings of social connection were positively related to neural activity to social warmth. However, naltrexone (vs placebo) disrupted these effects by (i) reducing VS and MI activity to social and physical warmth, (ii) erasing the subjective experience-brain association to social warmth and (iii) disrupting the neural overlap between social and physical warmth. Results provide additional support for the theory that social and physical warmth share neurobiological, opioid receptor-dependent mechanisms and suggest multiple routes by which social connections may be maintained.

No Evidence That Experiencing Physical Warmth Promotes Interpersonal Warmth

Abstract. Williams and Bargh (2008) reported that holding a hot cup of coffee caused participants to judge a person’s personality as warmer and that holding a therapeutic heat pad caused participants to choose rewards for other people rather than for themselves. These experiments featured large effects ( r = .28 and .31), small sample sizes (41 and 53 participants), and barely statistically significant results. We attempted to replicate both experiments in field settings with more than triple the sample sizes (128 and 177) and double-blind procedures, but found near-zero effects ( r = −.03 and .02). In both cases, Bayesian analyses suggest there is substantially more evidence for the null hypothesis of no effect than for the original physical warmth priming hypothesis.

Suppressing the Chills: Effects of Musical Manipulation on the Chills Response

Research on musical chills has linked the response to multiple musical features; however, there exists no study that has attempted to manipulate musical stimuli to enable causal inferences, meaning current understanding is based mainly on correlational evidence. In the current study, participants who regularly experience chills (N = 24) listened to an original and manipulated version of three pieces reported to elicit chills in a previous survey. Predefined chills sections were removed to create manipulated conditions. The effects of these manipulations on the chills response were assessed through continuous self-reports, and skin conductance measurements. Results show that chills were significantly less frequent following stimulus manipulation across all three pieces. Continuous measurements of chills intensity were significantly higher in the chills sections compared with control sections in the pieces; similar patterns were found for phasic skin conductance, although some differences emerged. Continuous measurements also correlated with psychoacoustic features such as loudness, brightness and roughness in two of the three pieces. Findings are discussed in terms of understanding structural and acoustic features and chills experiences within their local music contexts, the necessity of experimental approaches to musical chills, and the possibility of different features activating different underlying mechanisms.

The Human Penguin Project: Climate, Social Integration, and Core Body Temperature

Social thermoregulation theory posits that modern human relationships are pleisiomorphically organized around body temperature regulation. In two studies (N = 1755) designed to test the principles from this theory, we used supervised machine learning to identify social and non-social factors that relate to core body temperature. This data-driven analysis found that complex social integration (CSI), defined as the number of high-contact roles one engages in, is a critical predictor of core body temperature. We further used a cross-validation approach to show that colder climates relate to higher levels of CSI, which in turn relates to higher CBT (when climates get colder). These results suggest that despite modern affordances for regulating body temperature, people still rely on social warmth to buffer their bodies against the cold.

Effects of inflammation on social processes and implications for health

Although at first glance inflammation and social behavior may appear unrelated, research points to an important role for inflammation in shaping social processes. This review summarizes findings in this field, specifically highlighting work that provides support for the idea that inflammation can lead to (1) increases in sensitivity to negative, threatening social experiences and (2) increases in sensitivity to positive, socially rewarding experiences. These diverging sensitivities in response to inflammation may depend on context and be adaptive for recuperation and recovery from illness. This review also discusses the implications of these findings for health and future research, including implications for depression, loneliness, and inflammatory disorders.

Washing away your sins in the brain: physical cleaning and priming of cleaning recruit different brain networks after moral threat

The association between moral purity and physical cleanliness has been widely discussed recently. Studies found that moral threat initiates the need of physical cleanliness, but actual physical cleaning and priming of cleaning have inconsistent effects on subsequent attitudes and behaviors. Here, we used resting-state functional magnetic resonance imaging to explore the underlying neural mechanism of actual physical cleaning and priming of cleaning. After recalling moral transgression with strong feelings of guilt and shame, participants either actually cleaned their faces with a wipe or were primed with cleanliness through viewing its pictures. Results showed that actual physical cleaning reduced the spontaneous brain activities in the right insula and MPFC, regions that involved in embodied moral emotion processing, while priming of cleaning decreased activities in the right superior frontal gyrus and middle frontal gyrus, regions that participated in executive control processing. Additionally, actual physical cleaning also changed functional connectivity between insula/MPFC and emotion related regions, whereas priming of cleaning modified connectivity within both moral and sensorimotor areas. These findings revealed that actual physical cleaning and priming of cleaning led to changes in different brain regions and networks, providing neural evidence for the inconsistent effects of cleanliness on subsequent attitudes and behaviors.

Incidental haptic sensations influence judgment of crimes

Extralegal factors may influence judicial outcomes. Here we investigated the experience of incidental haptic sensations on the harshness of punishment recommendations. Based on recent theories of embodiment, which claim that cognitive representations are structured by metaphorical mappings from sensory experience, we hypothesized that tactile priming with hard objects would cause subjects to recommend harsher sentences (to be ‘hard on crime’). Furthermore, the theory of embodiment predicts that this effect should be based on sensorimotor brain activation during the judging process. In order to test this we presented participants with scenarios that described various crimes while scanning their brain activity with fMRI. Participants were then asked to rate how severely they would sentence the delinquents. Before the scenarios, the participants were primed by touching either a hard or a soft object. Results revealed tha t hard priming led participants to recommend harder punishments. These results were accompanied by activation of somatosensory brain areas during the judging phase. This outcome is in line with simulation assumptions of the embodiment theory and proposes a central role of the sensorimotor cortices for embodied metaphors. Thus, incidental tactile experiences can influence our abstract cognitions and even how hard we are on criminals.

A Social Safety Net: Developing a Model of Social-Support Figures as Prepared Safety Stimuli

Although the presence of social-support figures (e.g., close friends and family members) is known to increase feelings of safety, reduce threat responses, and improve health, the route by which these effects occur is not well understood. One explanation is that social-support figures are members of a powerful category of safety signals—prepared safety stimuli. Here, we review research demonstrating that social-support figures act as prepared safety stimuli and explore the impact that these unique safety stimuli have on fear-learning processes. According to recent work, the presence of social-support figures both reduces fear acquisition and enhances fear extinction, ultimately decreasing perceptions of threat. These findings shed light on the route by which social support buffers against threat and illustrate the unique properties of prepared safety stimuli and how they might be used to improve mental and physical health outcomes.

Central neural substrates involved in temperature discrimination, thermal pain, thermal comfort, and thermoregulatory behavior

A phylogenetically novel pathway that emerged with primate encephalization is described, which conveys high-fidelity cutaneous thermosensory activity in "labeled lines" to a somatotopic map in the dorsal posterior insular cortex. It originates in lamina I of the superficial dorsal horn and ascends by way of the lateral spinothalamic tract and a distinct region in posterolateral thalamus. It evolved from the homeostatic sensory activity that represents the physiologic (interoceptive) condition of the body and drives the central autonomic network, which underlies all affective feelings from the body. Accordingly, human discriminative thermal sensations are accompanied by thermally motivated behaviors and thermal feelings of comfort or discomfort (unless neutral), which evidence suggests are associated with activity in the insular, cingulate, and orbitofrontal cortices, respectively. Yet, the substrates for thermoregulatory behavior have not been established, and several strong candidates (including the hypothalamus and the bed nucleus of the stria terminalis) are discussed. Finally, the neural underpinnings for relationships between thermal affect and social feelings (warm-positive/cold-negative) are addressed, including the association of hyperthermia with clinical depression.

Perceptual-Semantic Congruency Facilitates Semantic Discrimination of Thermal Qualities

The ability to sense temperature is vital to our life. It signals the environmental condition, reflects the physiological conditions of our own body, and generates feelings of pleasantness or unpleasantness. Moreover, recent studies have demonstrated implicit associations between physical temperature and social/emotional concepts, suggesting the processing of temperature may even influence cognition. In this work, we examined the effect of physical warmth and coldness on semantic cognition. Participants performed speeded target categorization for thermal descriptors in the form of semantic words or illustrative figures representing the thermal qualities “warm” or “cold” while physical thermal stimulation was presented. We compared the average reaction time (RT) for the congruent and incongruent conditions managed by response key assignments. In the congruent condition, the response key for the symbol associated with warmth (coldness) was assigned to the hand with warm (cold) thermal stimulation, and in the incongruent condition the key assignment was reversed. Our results demonstrate that the average RT in the congruent condition was faster than in the incongruent one for both forms of thermal descriptors, suggesting that the experience of physical temperature facilitates the internal processing of the meaning of thermal quality.

Experiencing physical warmth affects implicit attitudes and altruistic behavior toward outgroup in females

Objective

Experiencing physical warmth has been demonstrated to influence interpersonal warmth. However, the effects of this metaphorical link in an intergroup context is not clear. The current study aimed to investigate the effect of physical warmth on implicit attitudes and behavior toward outgroup members in a Japanese–Chinese intergroup context. After touching either a warm or cold cup for 3 min, the Japanese participants were required to complete the single-target implicit association test, which aimed to measure their implicit attitudes toward imagined Chinese people, and to express their willingness to participate in the experiments of a Chinese individual whom they interacted directly without compensation, aiming to measure their prosocial behavior toward a real outgroup member.

Results

The results demonstrated that female participants who touched the warm (vs. cold) cup showed more positive attitudes and helping behavior toward the Chinese individual. Furthermore, the correlation between those attitudes and helping behaviors supports the effects of enhanced implicit attitudes and further suggests that experiencing physical warmth could increase prosocial response to outgroup members in real interactions. However, the male participants showed a reversed, but not statistically significant, effect of physical warmth on the implicit attitude.

Electronic supplementary material

The online version of this article (10.1186/s13104-017-2972-3) contains supplementary material, which is available to authorized users.

Neural correlates of ambient thermal sensation: An fMRI study

An increasing number of biometeorological and psychological studies have demonstrated the importance and complexity of the processes involved in environmental thermal perception in humans. However, extant functional imaging data on thermal perception have yet to fully reveal the neural mechanisms underlying these processes because most studies were performed using local thermal stimulation and did not dissociate thermal sensation from comfort. Thus, for the first time, the present study employed functional magnetic resonance imaging (fMRI) and manipulated ambient temperature during brain measurement to independently explore the neural correlates of thermal sensation and comfort. There were significant correlations between the sensation of a lower temperature and activation in the left dorsal posterior insula, putamen, amygdala, and bilateral retrosplenial cortices but no significant correlations were observed between brain activation and thermal comfort. The dorsal posterior insula corresponds to the phylogenetically new thermosensory cortex whereas the limbic structures (i.e., amygdala and retrosplenial cortex) and dorsal striatum may be associated with supramodal emotional representations and the behavioral motivation to obtain heat, respectively. The co-involvement of these phylogenetically new and old systems may explain the psychological processes underlying the flexible psychological and behavioral thermo-environmental adaptations that are unique to humans.

"Lacking warmth": Alexithymia trait is related to warm-specific thermal somatosensory processing

Alexithymia is a personality trait involving deficits in emotional processing. The personality construct has been extensively validated, but the underlying neural and physiological systems remain controversial. One theory suggests that low-level somatosensory mechanisms act as somatic markers of emotion, underpinning cognitive and affective impairments in alexithymia. In two separate samples (total N=100), we used an established Quantitative Sensory Testing (QST) battery to probe multiple neurophysiological submodalities of somatosensation, and investigated their associations with the widely-used Toronto Alexithymia Scale (TAS-20). Experiment one found reduced sensitivity to warmth in people with higher alexithymia scores, compared to individuals with lower scores, without deficits in other somatosensory submodalities. Experiment two replicated this result in a new group of participants using a full-sample correlation between threshold for warm detection and TAS-20 scores. We discuss the relations between low-level thermoceptive function and cognitive processing of emotion.

Arginine Vasopressin Effects on Subjective Judgments and Neural Responses to Same and Other-Sex Faces in Men and Women

Arginine vasopressin (AVP) influences social and emotional behaviors across a wide range of species. In humans, intranasal AVP has been previously shown to alter physiological responses to and subjective judgments of same-sex faces in both men and women. The present study attempted to elucidate the neural mechanism for these effects by randomizing 40 healthy men and 40 healthy women to treatment with either 40 IU intranasal AVP or a saline placebo approximately 30 min before imaging their brain function with fMRI as they viewed same and other-sex faces. All subjects were also scanned a second time several days later with no treatment to evaluate the persistence of AVP effects over time. AVP acutely increased positive ratings of same-sex faces in women, with some evidence that these effects persisted until the second scan. While AVP had no acute effects on same-sex ratings in men, AVP increased positive ratings of same-sex faces several days later. On the other hand, AVP had no effect on other-sex face judgments in either sex. AVP modulation of brain function was focused on the nucleus accumbens (NAc) and the lateral septum, two reward processing areas involved in the formation of social bonds. AVP provoked acute increases in right NAc and bilateral lateral septum responses to female faces among men, with left lateral septum responses persisting over time while right NAc responses reversed over time. Finally, AVP modulated hypothalamic activation to faces in both men and women. The present study therefore indicates that intranasal AVP affects subjective ratings and neural responses to same and other-sex faces in men and women, with some effects persisting and others emerging over time. Future studies should investigate whether AVP effects are modulated by individual variables such as genotype, personality, or attachment style as previously reported for other nonapeptides.

Helping Others, Warming Yourself: Altruistic Behaviors Increase Warmth Feelings of the Ambient Environment

Altruistic behaviors typically improve the welfare of the recipient at the cost of the performer's resources and energy. Do altruistic performers obtain any positive internal reward from altruistic behaviors? We conducted six experiments to explore whether altruistic behaviors could increase performer's warmth perception of the ambient environment. The first three studies focused on crisis situations. A retrospective field study (Study 1, with Hurricane Sandy) and two laboratory studies (Studies 2a and 2b, with an earthquake scenario) found that people who helped others felt warmer of the ambient environment than people who did not. We extended to daily life situations and found that participants who performed helping behaviors in laboratory (either voluntarily in Study 3a or randomly assigned to in Study 3b) and passers-by who donated to a charity (Study 4) reported warmer perception of the ambient environment than those who did not. These findings suggested an immediate internal reward of altruism.

Neural reuse leads to associative connections between concrete (physical) and abstract (social) concepts and motives

Consistent with neural reuse theory, empirical tests of the related "scaffolding" principle of abstract concept development show that higher-level concepts "reuse" and are built upon fundamental motives such as survival, safety, and consumption. This produces mutual influence between the two levels, with far-ranging impacts from consumer behavior to political attitudes.

A Pilot Study Examining Physical and Social Warmth: Higher (Non-Febrile) Oral Temperature Is Associated with Greater Feelings of Social Connection

An emerging literature suggests that experiences of physical warmth contribute to social warmth-the experience of feeling connected to others. Thus, thermoregulatory systems, which help maintain our relatively warm internal body temperatures, may also support feelings of social connection. However, the association between internal body temperature and feelings of connection has not been examined. Furthermore, the origins of the link between physical and social warmth, via learning during early experiences with a caregiver or via innate, co-evolved mechanisms, remain unclear. The current study examined the relationship between oral temperature and feelings of social connection as well as whether early caregiver experiences moderated this relationship. Extending the existing literature, higher oral temperature readings were associated with greater feelings of social connection. Moreover, early caregiver experiences did not moderate this association, suggesting that the physical-social warmth overlap may not be altered by early social experience. Results provide additional support for the link between experiences of physical warmth and social warmth and add to existing theories that highlight social connection as a basic need on its own.

Opioids and social bonding: naltrexone reduces feelings of social connection

Close social bonds are critical to a happy and fulfilled life and yet little is known, in humans, about the neurochemical mechanisms that keep individuals feeling close and connected to one another. According to the brain opioid theory of social attachment, opioids may underlie the contented feelings associated with social connection and may be critical to continued bonding. However, the role of opioids in feelings of connection toward close others has only begun to be examined in humans. In a double-blind, placebo-controlled, crossover study of naltrexone (an opioid antagonist), 31 volunteers took naltrexone for 4 days and placebo for 4 days (separated by a 10-day washout period). Participants came to the laboratory once on the last day of taking each drug to complete a task designed to elicit feelings of social connection. Participants also completed daily reports of feelings of social connection while on naltrexone and placebo. In line with hypotheses, and for the first time in humans, results demonstrated that naltrexone (vs placebo) reduced feelings of connection both in the laboratory and in daily reports. These results highlight the importance of opioids for social bonding with close others, lending support to the brain opioid theory of social attachment.

Keep it cool: temperature priming effect on cognitive control

The effect of physical temperature on cognition and behavior has been the focus of extensive research in recent years, demonstrating that embodied concepts are grounded in, and shaped by, sensorimotor physical experiences. Nevertheless, less is known about how experienced and perceived temperatures affect cognitive control, one of humans core executive functions. In the present work, we primed participants with cool versus warm temperature using a between participants manipulation of physical touch experience (Experiment 1), and a within participants manipulation of seeing landscape views associated with cool vs. warm temperatures (Experiment 2). In both experiments, cool compared to warm temperatures lead to improved performance on an anti-saccade task, an established cognitive control measure. Implications are discussed.

The repurposed social brain

Human social intelligence depends on a diverse array of perceptual, cognitive, and motivational capacities. Some of these capacities depend on neural systems that may have evolved through modification of ancestral systems with non-social or more limited social functions (evolutionary repurposing). Social intelligence, in turn, enables new forms of repurposing within the lifetime of an individual (cultural and instrumental repurposing), which entail innovating over and exploiting pre-existing circuitry to meet problems our brains did not evolve to solve. Considering these repurposing processes can provide insight into the computations that brain regions contribute to social information processing, generate testable predictions that usefully constrain social neuroscience theory, and reveal biologically imposed constraints on cultural inventions and our ability to respond beneficially to contemporary challenges.

Common and distinct neural mechanisms of the fundamental dimensions of social cognition

In the present study, we used a valence classification task to investigate the common and distinct neural basis of the two fundamental dimensions of social cognition (agency and communion) using functional magnetic resonance imaging (fMRI). The results showed that several brain areas associated with mentalizing, along with the inferior parietal gyrus in the mirror system, showed overlap in response to both agentic and communal words. These findings suggest that both content categories are related to the neural basis of social cognition; further, several areas in the default mode network (DMN) showed similar deactivations between agency and communion, reflecting task-induced deactivation (TID). In terms of distinct activations, the findings indicated greater deactivations for communal than agentic content in the ventral anterior cingulate (vACC) and medial orbitofrontal cortex (mOFC). Communion also showed greater activation in some visual areas compared to agentic content, including occipital gyrus, lingual gyrus, and fusiform gyrus. These activations may reflect greater allocation of attentional resources to visual areas when processing communal content, or inhibition of cognitive activity irrelevant to task performance. If so, this suggests greater attention and engagement with communion-related content. The present research thus suggests common and differential activations for agency- versus communion-related content.

Blocking opioids attenuates physical warmth-induced feelings of social connection

"Heartwarming" social experiences, when one feels interpersonally connected to others, have recently been linked with physical warmth. According to one theory (Panksepp, 1998), "social warmth" and physical warmth may be closely linked because both experiences are supported by similar neurobiological mechanisms; however, the neurochemical substrates underlying this overlap have not been explored. Here, an opioid antagonist, naltrexone, was administered in order to examine the role of opioids, previously shown to alter temperature and social bonding behavior, on perceived thermal intensity, general positive affect, and feelings of social connection from physical warmth. Thirty-one participants took both naltrexone and a placebo and completed a temperature manipulation task (held a warm pack, cold pack, and neutral object) while on each drug. Replicating previous research, holding a warm (vs. a cold or neutral) object increased feelings of social connection. Moreover, blocking opioids reduced this effect. Hence, naltrexone specifically reduced feelings of social connection to holding a warm (vs. neutral) object but not to holding a cold (vs. neutral) object. These results lend further support to the theory that social and physical warmth share neurobiological, opioid receptor dependent mechanisms.