The science of interpersonal touch: an overview

C-tactile afferent stimulating touch carries a positive affective value

The rewarding sensation of touch in affiliative interactions is hypothesized to be underpinned by a specialized system of nerve fibers called C-Tactile afferents (CTs), which respond optimally to slowly moving, gentle touch, typical of a caress. However, empirical evidence to support the theory that CTs encode socially relevant, rewarding tactile information in humans is currently limited. While in healthy participants, touch applied at CT optimal velocities (1-10cm/sec) is reliably rated as subjectively pleasant, neuronopathy patients lacking large myelinated afferents, but with intact C-fibres, report that the conscious sensation elicited by stimulation of CTs is rather vague. Given this weak perceptual impact the value of self-report measures for assessing the specific affective value of CT activating touch appears limited. Therefore, we combined subjective ratings of touch pleasantness with implicit measures of affective state (facial electromyography) and autonomic arousal (heart rate) to determine whether CT activation carries a positive affective value. We recorded the activity of two key emotion-relevant facial muscle sites (zygomaticus major—smile muscle, positive affect & corrugator supercilii—frown muscle, negative affect) while participants evaluated the pleasantness of experimenter administered stroking touch, delivered using a soft brush, at two velocities (CT optimal 3cm/sec & CT non-optimal 30cm/sec), on two skin sites (CT innervated forearm & non-CT innervated palm). On both sites, 3cm/sec stroking touch was rated as more pleasant and produced greater heart rate deceleration than 30cm/sec stimulation. However, neither self-report ratings nor heart rate responses discriminated stimulation on the CT innervated arm from stroking of the non-CT innervated palm. In contrast, significantly greater activation of the zygomaticus major (smiling muscle) was seen specifically to CT optimal, 3cm/sec, stroking on the forearm in comparison to all other stimuli. These results offer the first empirical evidence in humans that tactile stimulation that optimally activates CTs carries a positive affective valence that can be measured implicitly.

The Development of Tactile Perception

Touch is the first of our senses to develop, providing us with the sensory scaffold on which we come to perceive our own bodies and our sense of self. Touch also provides us with direct access to the external world of physical objects, via haptic exploration. Furthermore, a recent area of interest in tactile research across studies of developing children and adults is its social function, mediating interpersonal bonding. Although there are a range of demonstrations of early competence with touch, particularly in the domain of haptics, the review presented here indicates that many of the tactile perceptual skills that we take for granted as adults (e.g., perceiving touches in the external world as well as on the body) take some time to develop in the first months of postnatal life, likely as a result of an extended process of connection with other sense modalities which provide new kinds of information from birth (e.g., vision and audition). Here, we argue that because touch is of such fundamental importance across a wide range of social and cognitive domains, it should be placed much more centrally in the study of early perceptual development than it currently is.

The role of touch in acupuncture treatment

Acupuncture is a therapeutic treatment that is characterised by the insertion of a needle at a particular location on the body. Acupuncture stimulation includes sensory-discriminative and affective-social touch dimensions. In this review, we discuss the role of touch during acupuncture stimulation with an emphasis on the therapeutic, sensory-discriminative and affective-social aspects. In the discriminative dimension, de qi, which is associated with needling, includes a combination of various sensations, such as heaviness, numbness, soreness and distension. Achieving the appropriate de qi sensation appears to be fundamental to the therapeutic outcome following acupuncture treatment. In the affective dimension, the acupuncture procedure typically includes gentle manual touch stimulation, which induces feelings of calm and well-being, perhaps by activating C tactile fibres. Enhanced activity of C tactile afferents may induce a 'limbic touch' response, resulting in emotional and hormonal reactions. Because acupuncture is a 'therapist intensive' and complex intervention, it is necessary to understand the role of social touch between the practitioner and patient. Both sensory-discriminative and affective-social touch aspects play an important role in the therapeutic effect of acupuncture treatment in clinical practice.

More Than Just Sex: Affection Mediates the Association Between Sexual Activity and Well-Being

Positive interpersonal interactions such as affection are central to well-being. Sex is associated with greater individual well-being, but little is known about why this occurs. We predicted that experienced affection would account for the association between sex and well-being. Cross-sectional results indicated that affection mediated the association between sex and both life satisfaction (Study 1) and positive emotions (however, among men only in Study 2). In Study 3, an experience sampling study with 106 dual-earner couples with children, affection mediated the association between sex and increased positive affect in daily life. Cross-lagged analyses in Study 3 to 4 supported the predicted direction of the associations. Moreover, the strength of the daily association between sex and positive affect predicted both partners' relationship satisfaction 6 months later. Our findings underscore the importance of affection and positive affect for understanding how sex promotes well-being and has long-term relational benefits.

Inter-Individual Differences in Vicarious Tactile Perception: a View Across the Lifespan in Typical and Atypical Populations

Touch is our most interpersonal sense, and so it stands to reason that we represent not only our own bodily experiences, but also those felt by others. This review will summarise brain and behavioural research on vicarious tactile perception (mirror touch). Specifically, we will focus on vicarious touch across the lifespan in typical and atypical groups, and will identify the knowledge gaps that are in urgent need of filling by examining what is known about how individuals differ within and between typical and atypical groups.

A dyadic stimulus set of audiovisual affective displays for the study of multisensory, emotional, social interactions

We describe the creation of the first multisensory stimulus set that consists of dyadic, emotional, point-light interactions combined with voice dialogues. Our set includes 238 unique clips, which present happy, angry and neutral emotional interactions at low, medium and high levels of emotional intensity between nine different actor dyads. The set was evaluated in a between-design experiment, and was found to be suitable for a broad potential application in the cognitive and neuroscientific study of biological motion and voice, perception of social interactions and multisensory integration. We also detail in this paper a number of supplementary materials, comprising AVI movie files for each interaction, along with text files specifying the three dimensional coordinates of each point-light in each frame of the movie, as well as unprocessed AIFF audio files for each dialogue captured. The full set of stimuli is available to download from: http://motioninsocial.com/stimuli_set/ .

Affective touch awareness in mental health and disease relates to autistic traits - An explorative neurophysiological investigation

Affective touch is important for social interaction within families and groups and there is evidence that unmyelinated C tactile fibers are involved in this process. Individuals with autism spectrum disorders show alterations in the perception and processing of affective touch. sThus, we hypothesized that affective touch awareness based on C tactile fiber activation is impaired in individuals with high levels of autistic trait. The pleasantness perception of optimal and suboptimal C tactile stimuli was tested in an explorative study in 70 patients recruited from an outpatient psychotherapy clinic and 69 healthy comparison subjects. All participants completed questionnaires about autistic traits, depressive symptomatology, childhood maltreatment, and about the daily amount of touch. Relative to comparison subjects, patients reported engaging in touch less frequently in daily life and rated touch less pleasant. Reduced valence ratings of touch were explained by childhood maltreatment but not by any particular disorder or depression severity. Among all tested variables, the affective touch awareness correlated with autistic traits only - in patients as well as in comparison subjects. Taken together, individuals with mental health issues have a lower baseline of expression and reception of affective touch. Autistic traits and childhood maltreatment modulate the experience of affective touch.

Cooperation in lovers: An fNIRS-based hyperscanning study

This study investigated interactive exchange in lovers and the associated interpersonal brain synchronization (IBS) using functional near-infrared spectroscopy (fNIRS)-based hyperscanning. Three types of female-male dyads, lovers, friends, and strangers, performed a cooperation task during which brain activity was recorded in right frontoparietal regions. We measured better cooperative behavior in lover dyads compared with friend and stranger dyads. Lover dyads demonstrated increased IBS in right superior frontal cortex, which also covaried with their task performance. Granger causality analyses in lover dyads revealed stronger directional synchronization from females to males than from males to females, suggesting different roles for females and males during cooperation. Our study refines the theoretical explanation of romantic interaction between lovers. Hum Brain Mapp 38:831-841, 2017. © 2016 Wiley Periodicals, Inc.

Remember Hard But Think Softly: Metaphorical Effects of Hardness/Softness on Cognitive Functions

Previous studies have found that bodily stimulation, such as hardness biases social judgment and evaluation via metaphorical association; however, it remains unclear whether bodily stimulation also affects cognitive functions, such as memory and creativity. The current study used metaphorical associations between “hard” and “rigid” and between “soft” and “flexible” in Chinese, to investigate whether the experience of hardness affects cognitive functions whose performance depends prospectively on rigidity (memory) and flexibility (creativity). In Experiment 1, we found that Chinese-speaking participants performed better at recalling previously memorized words while sitting on a hard-surface stool (the hard condition) than a cushioned one (the soft condition). In Experiment 2, participants sitting on a cushioned stool outperformed those sitting on a hard-surface stool on a Chinese riddle task, which required creative/flexible thinking, but not on an analogical reasoning task, which required both rigid and flexible thinking. The results suggest the hardness experience affects cognitive functions that are metaphorically associated with rigidity or flexibility. They support the embodiment proposition that cognitive functions and representations can be grounded in bodily states via metaphorical associations.

From Sweeping to the Caress: Similarities and Discrepancies between Human and Non-Human Primates' Pleasant Touch

Affective touch plays a key role in affiliative behavior, offering a mechanism for the formation and maintenance of social bonds among conspecifics, both in humans and non-human primates. Furthermore, it has been speculated that the CT fiber system is a specific coding channel for affiliative touch that occurs during skin-to-skin interactions with conspecifics. In humans, this touch is commonly referred to as the caress, and its correlation with the CT fiber system has been widely demonstrated. It has been hypothesized that the sweeping touch that occurs during grooming in non-human primates may modulate the CT fibers, with recent preliminary studies on rhesus monkeys supporting this hypothesis. The present mini-review proposes a comparison between the pleasant touch, caress and sweeping of humans and non-human primates, respectively. The currently available data was therefore reviewed regarding (i) the correlation between pleasant touch and CT fibers both in humans and non-human primates, (ii) the autonomic effects, (iii) the encoding at the central nervous system, (iv) the development from early life to adulthood, and (v) the potential applications of pleasant touch in the daily lives of both humans and non-human primates. Moreover, by considering both the similarities and discrepancies between the human caress and non-human primate sweeping, a possible evolutionary mechanism can be proposed that has developed from sweeping as a utilitarian action with affiliative meaning among monkeys, to the caress as a purely affective gesture associated with humans.

Pointing to others: How the target gender influences pointing performance

Pointing is a communicative gesture that allows individuals to share information about surrounding objects with other humans. Patients with heterotopagnosia are specifically impaired in pointing to other humans' body parts but not in pointing to themselves or to objects. Here, we describe a female patient with heterotopagnosia who was more accurate in pointing to men's body parts than to women's body parts. We replicated this gender effect in healthy participants with faster reaction times for pointing to men's body parts than to women's body parts. We discuss the role of gender stereotypes in explaining why it is more difficult to point to women than to men.

An Exploration of the Interaction Between Touch Avoidance and the Pleasant Touch (C-Tactile Afferent) System

C-tactile (CT) afferent fibers are optimally stimulated by slow gentle stroking, and an inverted U-shaped relationship exists between stroking velocity and pleasantness ratings of this type of touch. This study investigated whether an additional and potentially important variable, touch avoidance, interacts with this relationship. While a typical U-shaped velocity–pleasantness relationship was expected, those high in touch avoidance were expected to rate CT-targeted touch (1–10 cm/s) as less pleasant than those low in touch avoidance. Thirty-five participants rated the pleasantness of a brush stroked across their forearm at five velocities (0.3, 1, 3, 10, 30 cm/s) administered by a custom-built touch stimulator (“the touch device”). Participants also completed two self-report measures of touch avoidance. There was an inverted U-shaped relationship between velocity and pleasantness ratings, and high touch avoidance resulted in a downward shift of this curve. The downward shift was across all velocities, including those that do not maximally engage CT afferents. It appears that touch avoidance reduces the pleasantness of all kinds of touch in a similar way, and it is unlikely to be specifically related to CT afferent functioning. Other potential mechanisms leading to touch avoidance are discussed.

The neurophysiology of human touch and eye gaze and its effects on therapeutic relationships and healing: a scoping review protocol

REVIEW QUESTION/OBJECTIVE

The objective of this scoping review is to examine and map the range of neurophysiological impacts of human touch and eye gaze, and better understand their possible links to the therapeutic relationship and the process of healing. The specific question is "what neurophysiological impacts of human touch and eye gaze have been reported in relation to therapeutic relationships and healing?"

Reliability and Validity of the European Portuguese Version of the Social Touch Questionnaire

Social touch is essential for physical and emotional well-being. However, different meanings can be attributed to physical contact during social interactions and may generate bonding or avoidant behaviors. This personal and unique experience is not usually taken into account in health and social care services. The aim of this study is to produce a valid and reliable European Portuguese version of the Social Touch Questionnaire (STQ, Wilhelm et al. in Biol Psychol 58:181–202, 2001. doi:10.1016/S0301-0511(01)00113-2). The STQ is a self-report questionnaire for adolescents and adults measuring behaviors and attitudes towards social touch. The original version was translated into European Portuguese using a forward-back translation process and its feasibility was examined. To evaluate the psychometric properties, a total of 242 Portuguese university students participated in the study (21.3 ± 3.8 years). The STQ was considered feasible, showed adequate internal consistency (Cronbach’s α = .734), and the test–retest correlation with the STQ items demonstrated a high concordance between the tests over a two-week interval (ICC = .990; n = 50). Validity tests were performed, comparing the total score of the STQ with that of the anxiety and avoidance subscales of the Social Interaction and Performance Anxiety and Avoidance Scale (SIPAAS). A very significant conceptual convergence was confirmed between the STQ and with the SIPAAS-Anxiety (r = .64; p < .0001) and with the SIPAAS-Avoidance (r = .59; p < .0001). The exploratory factor analysis, with Promax rotation, revealed 3 factors: dislike of physical touch, liking of familiar physical touch and liking of public physical touch (Cronbach’s alphas ranged from .68 to .75). Psychometric properties confirmed the adaptation of the STQ to the Portuguese culture. It is a reliable and valid self-report questionnaire and it appears to be a useful tool to assess behaviors and attitudes towards social touch.

Empathy Predicts an Experimental Pain Reduction During Touch

Previous studies have provided evidence for pain-alleviating effects of segmental tactile stimulation, yet the effect of social touch and its underlying mechanism is still unexplored. Considering that the soma affects the way we think, feel, and interact with others, it has been proposed that touch may communicate emotions, including empathy, interacting with the identity of the toucher. Thus, the goal of the current study was to examine the analgesic effects of social touch, and to test the moderating role of the toucher's empathy in analgesia using an ecological paradigm. Tonic heat stimuli were administered to women. Concurrently, their partners either watched or touched their hands, a stranger touched their hands, or no one interacted with them. The results revealed diminished levels of pain during partners' touch compared with all other control conditions. Furthermore, taking into account the dyadic interaction, only during the touch condition we found 1) a significant relationship between the partners' pain ratings, and 2) a significant negative relationship between the male touchers' empathy and the pain experience of their female partners. The findings highlight the powerful analgesic effect of social touch and suggest that empathy between romantic partners may explain the pain-alleviating effects of social touch.

PERSPECTIVE

Pain research mostly concentrates on different factors around a single pain target, without taking into account various social interactions with the observers. Our findings support the idea that pain perception models should be extended, taking into account some psychological characteristics of observers. Our conclusions are on the basis of advanced statistical methods.

Neonatal face-to-face interactions promote later social behaviour in infant rhesus monkeys

In primates, including humans, mothers engage in face-to-face interactions with their infants, with frequencies varying both within and across species. However, the impact of this variation in face-to-face interactions on infant social development is unclear. Here we report that infant monkeys (Macaca mulatta) who engaged in more neonatal face-to-face interactions with mothers have increased social interactions at 2 and 5 months. In a controlled experiment, we show that this effect is not due to physical contact alone: monkeys randomly assigned to receive additional neonatal face-to-face interactions (mutual gaze and intermittent lip-smacking) with human caregivers display increased social interest at 2 months, compared with monkeys who received only additional handling. These studies suggest that face-to-face interactions from birth promote young primate social interest and competency.

Affectionate Touch to Promote Relational, Psychological, and Physical Well-Being in Adulthood: A Theoretical Model and Review of the Research

Throughout the life span, individuals engage in affectionate touch with close others. Touch receipt promotes well-being in infancy, but the impacts of touch in adult close relationships have been largely unexplored. In this article, we propose that affectionate touch receipt promotes relational, psychological, and physical well-being in adulthood, and we present a theoretical mechanistic model to explain why affectionate touch may promote these outcomes. The model includes pathways through which touch could affect well-being by reducing stress and by promoting well-being independent of stress. Specifically, two immediate outcomes of affectionate touch receipt—relational-cognitive changes and neurobiological changes—are described as important mechanisms underlying the effects of affectionate touch on well-being. We also review and evaluate the existing research linking affectionate touch to well-being in adulthood and propose an agenda to advance research in this area. This theoretical perspective provides a foundation for future work on touch in adult close relationships.

The impact of therapeutic massage on adult residents living with complex and high level disabilities: A brief report

BACKGROUND

Research into the effects of touch in disabled adults in residential care remains largely unexplored in the current literature. Evidence suggests however, that massage therapy may improve mood state, including anxiety and stress, reduce pain and improve sleep/wake behavior and fatigue. These benefits are of importance as they have substantial impact on quality of life.

PURPOSE

This pilot study evaluated the effect of therapeutic massage on the quality of life of adults with complex care needs living in residential care.

METHODS

Participants were recruited from three residential homes (Queensland, Australia) for 18-65 year olds with severe disability. 25 participants were recruited and received a massage program consisting of five weeks of twice weekly massages. Structured interviews were conducted pre-post intervention. Additionally, mood was ascertained preceding and following each massage session.

RESULTS

Mood of participants improved markedly immediately following massage session (p < 0.05) and pre-massage mood was observed to increase over the study period. However, pre- and post-intervention measures indicated massage did not improve pain, sleepiness, depression or stress levels or sustain positive mood three days post-intervention. Participants' satisfaction with their current health significantly improved (Z = -2.51, p = 0.012), as did their satisfaction with their current happiness (Z = -2.06, p = 0.04), suggesting that massage therapy offered some improvement in quality of life.

CONCLUSIONS

The results of this pilot indicates that massage may be of benefit to people living with high care needs and represents a practical innovation providing tactile stimulation that may be integrated into care.

Enhance placebo, avoid nocebo: How contextual factors affect physiotherapy outcomes

INTRODUCTION

Placebo and nocebo represent complex and distinct psychoneurobiological phenomena in which behavioural and neurophysiological modifications occur together with the application of a treatment. Despite a better understanding of this topic in the medical field, little is known about their role in physiotherapy.

PURPOSE

The aim of this review is: a) to elucidate the neurobiology behind placebo and nocebo effects, b) to describe the role of the contextual factors as modulators of the clinical outcomes in rehabilitation and c) to provide clinical and research guidelines on their uses.

IMPLICATIONS

The physiotherapist's features, the patient's features, the patient-physiotherapist relationship, the characteristics of the treatment and the overall healthcare setting are all contextual factors influencing clinical outcomes. Since every physiotherapy treatment determines a specific and a contextual effect, physiotherapists should manage the contextual factors as a boosting element of any manual therapy to improve placebo effects and avoid detrimental nocebo effects.

Impact of Mediated Intimate Interaction on Education: A Huggable Communication Medium that Encourages Listening

In this paper, we propose the introduction of human-like communication media as a proxy for teachers to support the listening of children in school education. Three case studies are presented on storytime fieldwork for children using our huggable communication medium called Hugvie, through which children are encouraged to concentrate on listening by intimate interaction between children and storytellers. We investigate the effect of Hugvie on children's listening and how they and their teachers react to it through observations and interviews. Our results suggest that Hugvie increased the number of children who concentrated on listening to a story and was welcomed by almost all the children and educators. We also discuss improvement and research issues to introduce huggable communication media into classrooms, potential applications, and their contributions to other education situations through improved listening.

Intimacy in Phone Conversations: Anxiety Reduction for Danish Seniors with Hugvie

There is a lack of physical contact in current telecommunications such as text messaging and Internet access. To challenge the limitation and re-embody telecommunication, researchers have attempted to introduce tactile stimulation to media and developed huggable devices. Previous experiments in Japan showed that a huggable communication technology, i.e., Hugvie decreased stress level of its female users. In the present experiment in Denmark, we aim to investigate (i) whether Hugvie can decrease stress cross-culturally, i.e., Japanese vs. Danish participants (ii), investigate whether gender plays a role in this psychological effect (stress reduction) and (iii) if there is a preference of this type of communication technology (Hugvie vs. a regular telephone). Twenty-nine healthy elderly participated (15 female and 14 male, M = 64.52 years, SD = 5.67) in Jutland, Denmark. The participants filled out questionnaires including State-Trait Anxiety Inventory, NEO Five Factor Inventory (NEO-FFI), and Becks Depression Inventory, had a 15 min conversation via phone or Hugvie and were interviewed afterward. They spoke with an unknown person of opposite gender during the conversation; the same two conversation partners were used during the experiment and the Phone and Hugvie groups were equally balanced. There was no baseline difference between the Hugvie and Phone groups on age or anxiety or depression scores. In the Hugvie group, there was a statistically significant reduction on state anxiety after meeting Hugvie (p = 0.013). The change in state anxiety for the Hugvie group was positively correlated with openness (r = 0.532, p = 0.041) as measured by the NEO-FFI. This indicates that openness to experiences may increase the chances of having an anxiety reduction from being with Hugvie. Based on the results, we see that personality may affect the participants’ engagement and benefits from Hugvie. We discuss the implications of the results and further elaborations.

Body Image and Anti-Fat Attitudes: An Experimental Study Using a Haptic Virtual Reality Environment to Replicate Human Touch

It is well documented that anti-fat attitudes influence the interactions individuals have with overweight people. However, testing attitudes through self-report measures is challenging. In the present study, we explore the use of a haptic virtual reality environment to physically interact with overweight virtual human (VH). We verify the hypothesis that duration and strength of virtual touch vary according to the characteristics of VH in ways similar to those encountered from interaction with real people in anti-fat attitude studies. A group of 61 participants were randomly assigned to one of the experimental conditions involving giving a virtual hug to a female or a male VH of either normal or overweight. We found significant associations between body image satisfaction and anti-fat attitudes and sex differences on these measures. We also found a significant interaction effect of the sex of the participants, sex of the VH, and the body size of the VH. Female participants hugged longer the overweight female VH than overweight male VH. Male participants hugged longer the normal-weight VH than the overweight VH. We conclude that virtual touch is a promising method of measuring attitudes, emotion and social interactions.

Children's Immediate Postoperative Distress and Mothers' and Fathers' Touch Behaviors

OBJECTIVE

This study examined mothers' and fathers' use of child-directed touch in the postanesthesia care unit.

METHODS

In all, 142 mothers and 112 fathers of 143 children aged 2-11 years undergoing outpatient surgery participated. Parent touch (instrumental, empathic) and child distress were coded. Mothers' and fathers' rates of touch were compared, and interrelations between touch and child distress were examined (overall and sequentially).

RESULTS

The proportion of mothers and fathers who used touch did not differ, but mothers' rates of touch were higher than fathers'. Parental instrumental touch and mothers embracing touch were positively correlated with children's distress. Mothers were more likely to use embracing touch in response to children's distress than at any other time.

CONCLUSIONS

Results point to potential differences in mothers' and fathers' roles in the postoperative setting, and potentially different functions of touch. Results suggest that mothers may provide embracing touch to soothe or prevent children's distress.

Effects of mediated social touch on affective experiences and trust

This study investigated whether communication via mediated hand pressure during a remotely shared experience (watching an amusing video) can (1) enhance recovery from sadness, (2) enhance the affective quality of the experience, and (3) increase trust towards the communication partner. Thereto participants first watched a sad movie clip to elicit sadness, followed by a funny one to stimulate recovery from sadness. While watching the funny clip they signaled a hypothetical fellow participant every time they felt amused. In the experimental condition the participants responded by pressing a hand-held two-way mediated touch device (a Frebble), which also provided haptic feedback via simulated hand squeezes. In the control condition they responded by pressing a button and they received abstract visual feedback. Objective (heart rate, galvanic skin conductance, number and duration of joystick or Frebble presses) and subjective (questionnaires) data were collected to assess the emotional reactions of the participants. The subjective measurements confirmed that the sad movie successfully induced sadness while the funny movie indeed evoked more positive feelings. Although their ranking agreed with the subjective measurements, the physiological measurements confirmed this conclusion only for the funny movie. The results show that recovery from movie induced sadness, the affective experience of the amusing movie, and trust towards the communication partner did not differ between both experimental conditions. Hence, feedback via mediated hand touching did not enhance either of these factors compared to visual feedback. Further analysis of the data showed that participants scoring low on Extraversion (i.e., persons that are more introvert) or low on Touch Receptivity (i.e., persons who do not like to be touched by others) felt better understood by their communication partner when receiving mediated touch feedback instead of visual feedback, while the opposite was found for participants scoring high on these factors. The implications of these results for further research are discussed, and some suggestions for follow-up experiments are presented.

Active Interpersonal Touch Gives Rise to the Social Softness Illusion

Social touch plays a powerful role in human life, with important physical and mental health benefits in development and adulthood. Touch is central in building the foundations of social interaction, attachment, and cognition [1–5], and early, social touch has unique, beneficial neurophysiological and epigenetic effects [6–9]. The recent discovery of a separate neurophysiological system for affectively laden touch in humans has further kindled scientific interest in the area [10, 11]. Remarkably, however, little is known about what motivates and sustains the human tendency to touch others in a pro-social manner. Given the importance of social touch, we hypothesized that active stroking elicits more sensory pleasure when touching others’ skin than when touching one’s own skin. In a set of six experiments (total N = 133) we found that healthy participants, mostly tested in pairs to account for any objective differences in skin softness, consistently judged another’s skin as feeling softer and smoother than their own skin. We further found that this softness illusion appeared selectively when the touch activated a neurophysiological system for affective touch in the receiver. We conclude that this sensory illusion underlies a novel, bodily mechanism of socio-affective bonding and enhances our motivation to touch others.

•

The social softness illusion reflects the sensory hedonics of active social touch

•

Stroking others’ skin feels softer and smoother than stroking our own skin

•

The illusion appears when the touch activates the receiver’s affective touch system

•

The illusion reflects a tactile mechanism of emotional sharing between individuals

Body maps in the infant brain

Researchers have examined representations of the body in the adult brain but relatively little attention has been paid to ontogenetic aspects of neural body maps in human infants. Novel applications of methods for recording brain activity in infants are delineating cortical body maps in the first months of life. Body maps may facilitate infants' registration of similarities between self and other - an ability that is foundational to developing social cognition. Alterations in interpersonal aspects of body representations might also contribute to social deficits in certain neurodevelopmental disorders.

Friendly touch increases gratitude by inducing communal feelings

Communion among people is easily identifiable. Close friends or relatives frequently touch each other and this physical contact helps identifying the type of relationship they have. We tested whether a friendly touch and benefits elicit the emotion of gratitude given the close link between gratitude and communal relations. In Study 1, we induced a communal mindset and manipulated friendly touch (vs. non-touch) and benefit to female participants by a female confederate. We measured pre- and post-benefit gratitude, communal feelings, and liking toward the toucher, as well as general affect. In Study 2, we manipulated mindset, friendly touch and benefit, and measured the same variables in female pairs (confederate and participants). In both studies the results showed a main effect of touch on pre-benefit gratitude: participants who were touched by the confederate indicated more gratitude than those not touched. Moreover, benefit increased gratitude toward a confederate in the absence of touch, but not in the presence of touch. Additionally, perceiving the relationship as communal, and not merely liking the confederate, or a positive mood mediated the link between touch and gratitude. The results further support a causal model where touch increases communal feelings, which in turn increase gratitude at the end of the interaction, after having received a benefit from the interaction partner. These results support a broader definition of gratitude as an emotion embodied in communal relationship cues.

The Relationship between Gentle Tactile Stimulation on the Fetus and Its Temperament 3 Months after Birth

OBJECTIVE

The aim of this study was to evaluate the effect of gentle tactile stimulation on the fetus in its temperament 3 months after birth.

METHOD

A total of 302 mother-3-month-infant dyads enrolled the retrospective cohort study. 76 mothers had regular gentle tactile stimulation on the fetus in their pregnancy; 62 mothers had irregular tactile stimulation on the fetus, and the rest of 164 mothers who had no tactile stimulation served as nonexposure group. Temperament was assessed using the EITS (a nine-dimensional scale of temperament).

RESULTS

Significant difference in temperament type was found among infants in 3 groups at 3 months of age. In the regular practice group, the babies with easy type temperament accounted for 73.7%, which was higher than that in irregular practice group (53.2%, P = 0.012) and that in the control group (42.1%, P < 0.001). Compared to infants in no practice group, the infants who had received regular gentle tactile stimulation before birth were lower in negative mood (P = 0.047) while higher in adaptability (P < 0.001), approach (P = 0.001), and persistence (P = 0.001), respectively.

CONCLUSION

Regular gentle tactile stimulation on fetus may promote the formation of easy type infant temperament.

When in Doubt, Reach Out

Social support is critical to personal and relational well-being. Yet, receiving support appears to be contingent upon adequately conveying need to a receptive partner who both understands and is willing to provide said support. Or is it? We provide the first evidence of a covert haptic support system between adult intimates, showing that literally reaching out to a loved one can result in feeling supported even when the receiver of haptic support requests does not perceive them as bids for comfort. We tested this by unobtrusively observing support interactions between dating partners. As expected, those experiencing distress were more likely to seek touch from their partners, which elicited responsive touch—even though receivers failed to discern need from support-seekers’ touch. Importantly, those who received responsive touch from their romantic partners felt more supported. Because touch begets touch, clear communication between intimates is not always necessary for successful support interactions.

A theory of social thermoregulation in human primates

Beyond breathing, the regulation of body temperature-thermoregulation-is one of the most pressing concerns for many animals. A dysregulated body temperature has dire consequences for survival and development. Despite the high frequency of social thermoregulation occurring across many species, little is known about the role of social thermoregulation in human (social) psychological functioning. We outline a theory of social thermoregulation and reconsider earlier research on people's expectations of their social world (i.e., attachment) and their prediction of the social world. We provide support and outline a research agenda that includes consequences for individual variation in self-regulatory strategies and capabilities. In our paper, we discuss physiological, neural, and social processes surrounding thermoregulation. Emphasizing social thermoregulation in particular, we appeal to the economy of action principle and the hierarchical organization of human thermoregulatory systems. We close with future directions of a crucial aspect of human functioning: the social regulation of body temperature.

Interpersonal touch suppresses visual processing of aversive stimuli

Social contact is essential for survival in human society. A previous study demonstrated that interpersonal contact alleviates pain-related distress by suppressing the activity of its underlying neural network. One explanation for this is that attention is shifted from the cause of distress to interpersonal contact. To test this hypothesis, we conducted a functional MRI (fMRI) study wherein eight pairs of close female friends rated the aversiveness of aversive and non-aversive visual stimuli under two conditions: joining hands either with a rubber model (rubber-hand condition) or with a close friend (human-hand condition). Subsequently, participants rated the overall comfortableness of each condition. The rating result after fMRI indicated that participants experienced greater comfortableness during the human-hand compared to the rubber-hand condition, whereas aversiveness ratings during fMRI were comparable across conditions. The fMRI results showed that the two conditions commonly produced aversive-related activation in both sides of the visual cortex (including V1, V2, and V5). An interaction between aversiveness and hand type showed rubber-hand-specific activation for (aversive > non-aversive) in other visual areas (including V1, V2, V3, and V4v). The effect of interpersonal contact on the processing of aversive stimuli was negatively correlated with the increment of attentional focus to aversiveness measured by a pain-catastrophizing scale. These results suggest that interpersonal touch suppresses the processing of aversive visual stimuli in the occipital cortex. This effect covaried with aversiveness-insensitivity, such that aversive-insensitive individuals might require a lesser degree of attentional capture to aversive-stimulus processing. As joining hands did not influence the subjective ratings of aversiveness, interpersonal touch may operate by redirecting excessive attention away from aversive characteristics of the stimuli.

Somatosensory pleasure circuit: from skin to brain and back

The skin senses serve a discriminative function, allowing us to manipulate objects and detect touch and temperature, and an affective/emotional function, manifested as itch or pain when the skin is damaged. Two different classes of nerve fibre mediate these dissociable aspects of cutaneous somatosensation: (i) myelinated A-beta and A-delta afferents that provide rapid information about the location and physical characteristics of skin contact; and (ii) unmyelinated, slow-conducting C-fibre afferents that are typically associated with coding the emotional properties of pain and itch. However, recent research has identified a third class of C-fibre afferents that code for the pleasurable properties of touch - c-tactile afferents or CTs. Clinical application of treatments that target pleasant, CT-mediated touch (such as massage therapy) could, in the future, provide a complementary, non-pharmacological means of treating both the physical and psychological aspects of chronic skin conditions such as itch and eczema.