Individual differences in affective touch: Behavioral inhibition and gender define how an interpersonal touch is perceived

Virtually simulated interpersonal touch negatively affects perceived closeness and social affiliation to an avatar partner

Interpersonal touch is an essential component of human non-verbal communication, facilitating social affiliation and bonding. With the widespread use of digital interfaces and online platforms in all realms of human interactions, there are fewer opportunities for communicating through touch. Popular online platforms that virtually simulate human interactions rely primarily on visual and auditory modalities, providing limited or no capacity for the exchange of tactile cues. Previous studies of virtual interactions have explored the simulation of social touch using haptic devices, but little is known about how the visual representation of interpersonal touch is perceived and integrated into a virtual social experience. In two studies we examined how the exchange of virtual touch mediated by simulated 3-dimensional human characters, or avatars, within an online virtual environment influenced affiliation towards an unfamiliar interaction partner. Surprisingly, the exchange of virtual touch negatively affected the perceived closeness and affiliation to the partner and the social evaluation of the interaction but did not affect the level of physiological arousal during the interaction. These results indicate that the visual representation of social touch is sufficient to virtually communicate touch-related cues that impact social affiliation, but the influence of touch may be dependent on the interaction context.

Role of medial prefrontal cortex and primary somatosensory cortex in self and other-directed vicarious social touch: a TMS study

Conflicting evidence points to the contribution of several key nodes of the 'social brain' to the processing of both discriminatory and affective qualities of interpersonal touch. Whether the primary somatosensory cortex (S1) and the medial prefrontal cortex (mPFC), two brain areas vital for tactile mirroring and affective mentalizing, play a functional role in shared representations of C-tactile (CT) targeted affective touch is still a matter of debate. Here, we used offline continuous theta-burst transcranial magnetic stimulation (cTBS) to mPFC, S1 and vertex (control) prior to participants providing ratings of vicarious touch pleasantness for self and others delivered across several body sites at CT-targeted velocities. We found that S1-cTBS led to a significant increase in touch ratings to the self, with this effect being positively associated to levels of interoceptive awareness. Conversely, mPFC-cTBS reduced pleasantness ratings for touch to another person. These effects were not specific for CT-optimal (slow) stroking velocities, but rather they applied to all types of social touch. Overall, our findings challenge the causal role of the S1 and mPFC in vicarious affective touch and suggest that self- vs other-directed vicarious touch responses might crucially depend on the specific involvement of key social networks in gentle tactile interactions.

Under the thin skin of narcissus: Facial muscle activity reveals amplified emotional responses to negative social evaluation in individuals with grandiose narcissistic traits

Individuals with grandiose narcissism exhibit enhanced antagonism and a defensive pattern of discordance between their emotional and physiological reactions to self-threatening evaluations. Although theoretical perspectives link narcissistic defensiveness to negative emotions, empirical evidence linking grandiose narcissism to emotional reactivity remains mixed. The current study used self-reported affect, electrocardiography, and facial electromyography (fEMG) to examine whether people scoring high in grandiose narcissism show amplified physiological and self-reported emotional reactivity to negative social evaluation. Following two challenging cognitive tasks, participants received negative and neutral feedback in a face-to-face evaluation situation. Receiving negative feedback decreased self-reported positive affect and dominance, slowed heart rate, and amplified fEMG activity related to frowning and eye constriction. Although self-reported emotional reactions were unrelated to grandiose narcissism, fEMG activity associated with negative affect was significantly enhanced by grandiose narcissism. In conclusion, individuals with higher levels of grandiose narcissism may not be willing to report overt emotional reactivity to self-threatening feedback, but physiological responses "beneath their thin skin" reveal amplified threat-related facial muscle activity suggestive of a negative emotional state.

Hedonic and autonomic responses in promoting affective touch

Interpersonal touch is intrinsically reciprocal since it entails a person promoting and another receiving the touch. While several studies have investigated the beneficial effects of receiving affective touch, the affective experience of caressing another individual remains largely unknown. Here, we investigated the hedonic and autonomic responses (skin conductance and heart rate) in the person promoting affective touch. We also examined whether interpersonal relationship, gender, and eye contact modulate these responses. As expected, caressing the partner was perceived as more pleasant than caressing a stranger, especially if the affective touch occurred together with mutual eye contact. Promoting affective touch to the partner also resulted in a decrease of both autonomic responses and anxiety levels, suggesting the occurrence of a calming effect. Additionally, these effects were more pronounced in females compared to males, indicating that hedonic and autonomic aspects of affective touch are modulated by both social relationship and gender. These findings show for the first time that caressing a beloved one is not only pleasant but also reduces autonomic responses and anxiety in the person promoting the touch. This might suggest that affective touch has an instrumental role for romantic partners in promoting and reinforcing their affective bonding.

Decomposing Neural Representational Patterns of Discriminatory and Hedonic Information during Somatosensory Stimulation

The ability to interrogate specific representations in the brain, determining how, and where, difference sources of information are instantiated can provide invaluable insight into neural functioning. Pattern component modeling (PCM) is a recent analytic technique for human neuroimaging that allows the decomposition of representational patterns in brain into contributing subcomponents. In the current study, we present a novel PCM variant that tracks the contribution of prespecified representational patterns to brain representation across areas, thus allowing hypothesis-guided employment of the technique. We apply this technique to investigate the contributions of hedonic and nonhedonic information to the neural representation of tactile experience. We applied aversive pressure (AP) and appetitive brush (AB) to stimulate distinct peripheral nerve pathways for tactile information (C-/CT-fibers, respectively) while patients underwent functional magnetic resonance imaging (fMRI) scanning. We performed representational similarity analyses (RSAs) with pattern component modeling to dissociate how discriminatory versus hedonic tactile information contributes to population code representations in the human brain. Results demonstrated that information about appetitive and aversive tactile sensation is represented separately from nonhedonic tactile information across cortical structures. This also demonstrates the potential of new hypothesis-guided PCM variants to help delineate how information is instantiated in the brain.

Uncovering terra incognita in the AHD design space: A review of affective haptic devices

Affective haptic devices (AHDs) have been developed with the aim of communicating touch acts, symbolic messages, emotions, and/or providing a sense of social awareness. Within AHDs, three categories can be distinguished: mediated social touch (MST), symbolic communication systems, and awareness systems. For each of these categories, prototypes have been developed and discussed in the literature. Each such prototype, however, describes but a small part of the design space of AHDs. What is lacking is a description of the design space itself—of all choices that can be considered during the design process. Such a description will allow for a more systematic exploration of AHD designs and provides a means of combining insights gained from individual point solutions (i.e., existing prototypes). Therefore, in this article, we provide a systematic description of the design space of AHDs and its underlying dimensions based on general (e.g., revisability or synchronicity) and AHD-specific (e.g., actuation type) communication system characteristics. This resulted in 17 design dimensions, each consisting of two or more categories (the design characteristics). Based on a systematic literature search from devices up to 2019, 89 AHD prototypes were identified, and each was classified on the design dimensions. The empirical analysis of where these AHDs are located in the design space revealed, first, that potentially interesting characteristics from mediated communication, such as revisability and reviewability, are underexplored in AHDs. Second, MST devices were found to often lack those system characteristics, such as real-time modalities, that seem crucial for providing the affordances needed to simulate social touch. In particular, when comparing symbolic and awareness devices to MST devices, we found the latter to more frequently lack some of the key characteristics of face-to-face communication (i.e., bi-directional and symmetric communication). Limitations and implications are discussed.

Vicarious ratings of self vs. other-directed social touch in women with and recovered from Anorexia Nervosa

Anorexia Nervosa (AN) is an eating pathology characterized by restricted eating, body image distortions and impaired socio-cognitive abilities. Altered responses to affective touch—a pleasant interoceptive stimulus hypothesised to involve activation of the C-Tactile (CT) system, may contribute to the aetiology and maintenance of this disorder. Here, we investigated whether third-party social touch vicarious ratings of different body sites at CT-optimal vs. non-CT optimal velocities differed in women with and recovered from AN (RAN) and healthy controls (HCs). Thirty-five HCs, 27 AN and 29 RAN provided pleasantness ratings for two different tasks designed to probe expectations of how touch is perceived by self (self-directed touch) vs. others (other-directed touch). Findings revealed that both clinical groups, compared to HCs, did not differ in their pleasantness ratings to touch for another but when evaluating touch for self, both clinical groups rated CT-optimal touch as less pleasant than HCs. These findings suggest that AN and RAN women demonstrate an atypical vicarious pleasantness response to affective touch involving self, but not others. Novel therapeutic approaches that help anorexics to better interpret or improve tolerance of affective tactile experiences involving the self may be an important addition to current standard treatments.

Exploring views on affective haptic devices in times of COVID-19

Affective haptic devices (AHDs) are communication technologies utilizing the sense of touch, and include mediated social touch (MST), symbolic haptic messaging, and awareness systems that, for example, let one feel another person's heartbeat. The COVID-19 pandemic and consequent social distancing measures have led to a reemphasis of the importance of social touch, and many people have experienced firsthand what it is like to miss touching loved ones. This offers an excellent opportunity to study people's intention to use AHDs. For this purpose, a survey study (n = 277) was conducted combining qualitative and quantitative data analysis methods. Touch deprivation, resulting from not being able to touch a loved one, was associated with intention to use AHDs: the more deprived an individual, the higher his or her intention to use AHDs. Technology readiness and touch aversion did not affect intention to use AHDs. AHDs for symbolic messaging gained higher interest than MST and awareness devices, and long-distance relationships were seen as the most likely scenario for using AHDs. Bi-directionality, synchronicity, and symmetry were regarded as important features for providing shared meaning and a sense of connectedness. Reviewability, multimodality, and actuation type were also deemed important. Limitations of the study and implications for the design of AHDs are discussed.

The off-line effect of affective touch on multisensory integration and tactile perceptual accuracy during the somatic signal detection task

Affective touch refers to the emotional and motivational facets of tactile sensation and has been linked to the activation of a specialised system of mechanosensory afferents (the CT system), that respond optimally to slow caress-like touch. Affective touch has been shown to play an important role in the building of the bodily self: the multisensory integrated global awareness of one’s own body. Here we investigated the effects of affective touch on subsequent tactile awareness and multisensory integration using the Somatic Signal Detection Task (SSDT). During the SSDT, participants were required to detect near-threshold tactile stimulation on their cheek, in the presence/absence of a concomitant light. Participants repeated the SSDT twice, before and after receiving a touch manipulation. Participants were divided into two groups: one received affective touch (CT optimal; n = 32), and the second received non-affective touch (non-CT optimal; n = 34). Levels of arousal (skin conductance levels, SCLs) and mood changes after the touch manipulation were also measured. Affective touch led to an increase in tactile accuracy, as indicated by less false reports of touch and a trend towards higher tactile sensitivity during the subsequent SSDT. Conversely, non-affective touch was found to induce a partial decrease in the correct detection of touch possibly due to a desensitization of skin mechanoreceptors. Both affective and non-affective touch induced a more positive mood and higher SCLs in participants. The increase in SCLs was greater after affective touch. We conclude that receiving affective touch enhances the sense of bodily self therefore increasing perceptual accuracy and awareness. Higher SCLs are suggested to be a possible mediator linking affective touch to a greater tactile accuracy. Clinical implications are discussed.

Affective touch topography and body image

Recent evidence suggests that altered responses to affective touch—a pleasant interoceptive stimulus associated with activation of the C-Tactile (CT) system—may contribute to the aetiology and maintenance of mental conditions characterised by body image disturbances (e.g., Anorexia Nervosa). Here, we investigated whether tactile pleasantness and intensity differ across body sites, and if individual differences in dysmorphic appearance concerns and body and emotional awareness might be associated with touch perceptions across body sites. To this end, we measured perceived pleasantness and intensity of gentle, dynamic stroking touches applied to the palm, forearm, face, abdomen and back of 30 female participants (mean age: 25.87±1.17yrs) using CT-optimal (3 cm/s) and non-CT optimal (0.3 and 30 cm/s) stroking touch. As expected, participants rated CT-targeted touch as more pleasant compared to the two non-CT optimal stroking touch at all body sites. Regardless of stroking velocity, touch applied to the abdomen elicited the lowest pleasantness ratings. Lower levels of emotional awareness, greater levels of interoceptive sensibility and of dysmorphic concerns were associated with lower preference for CT-optimal stroking touch applied to the forearm and the back. These findings begin to elucidate the link between CT sensitivity, dysmorphic appearance concerns and body and emotional awareness, which may have implications for future research looking to inform early interventions. Addressing impaired processing of affective interoceptive stimuli, such as CT-targeted touch, may be the key to current treatment approaches available for those populations at risk of disorders characterised by body image disturbance.

The influence of duration, arm crossing style, gender, and emotional closeness on hugging behaviour

Hugging is one of the most common types of affective touch encountered in everyday life. However, little is known about the factors that influence hugging evaluation and behaviour. Here, we aimed to assess how different hugs would be evaluated and whether they can affect mood. Furthermore, we aimed to investigate what kind of arm crossing is common in a naturalistic setting and whether arm crossing style could be predicted from gender, emotional closeness, and the height difference of huggers. We conducted two studies addressing these questions. In study 1, participants hugged a confederate for 1 second (s), 5 s or 10 s with two different arm crossing styles and reported how pleasant, arousing and under control the touch felt. Additionally, participants were asked about their mood ("self-ratings") immediately after, 3 minutes (min) after and 6 min after each hug. In study 2, participants were approached on campus and asked to share a hug, with arm crossing style being the dependent variable. The height difference, gender and self-rated emotional closeness to the hug partner were recorded as possible predictors for arm crossing style. Results from study 1 indicate that duration matters more than arm crossing style for hug pleasure, arousal, and control, with 1 s hugs being rated as least pleasant and under control than 5 s and 10 s hugs. Accordingly, 1 s hugs also resulted in lower pleasure self-ratings immediately post hug than 5 s and 10 s hugs. Arousal self-ratings were higher immediately post hug than several minutes after a hug. In study 2, gender was linked to arm crossing style, with male-male hug dyads exhibiting a different hugging style from female-female dyads. These findings are discussed in relation to previous hug research and gender differences in touch behaviour.

Affective Touch Reduces Electrically Induced Itch Experience

Introduction: Itch is a common symptom in dermatologic and other diseases and can have a severe impact on quality of life and mental health. As a proportion of patients with itch-symptoms is resistant to commonly used anti-histamine treatments, development of new treatments is desirable. Past research on pain, itch and affective touch (i.e. slow, gentle stroking of the skin activating C-tactile fibers) revealed an inhibitory relationship between affective touch and pain and between pain and itch. Given the overlap in neural processing between these three sensory submodalities, a possible interaction between affective touch and itch might be expected. This study investigated whether there is a relationship between itch and affective touch, and if so, whether affective touch inhibits itch.

Methodology: Itch was electrically induced with the use of electrodes that were placed at the ventral side of the wrist of 61 participants. A within-subject design was conducted with two conditions. An experimental -affective touch- condition (stroking the forearm with a soft brush at 3 cm/s) and a control -non-affective touch- condition (stroking the forearm with a soft brush at 18 cm/s). Touch was applied on the dorsal side of the forearm, the same arm as were the electrodes were placed. For each condition itch was induced for 20 min, with every 2 min a VAS-scale measurement of the level of experienced itch.

Results: Both types of touch reduced the experienced itch compared to baseline (p < 0.01, partial η² = 0.67). However, affective touch had an additional significant relieving effect compared to non-affective touch (p = 0.03, partial η²= 0.08). The alleviation of itch started after 2 min of stroking and continued to increase up till 6 min, where after the relieving effect stabilized but still persisted.

Conclusion: This finding suggest that affective touch, as with acute pain, has a relieving effect on electrically induced itch.

Bliss in and Out of the Body: The (Extra)Corporeal Space Is Impervious to Social Pleasant Touch

Slow, gentle stimulation of hairy skin is generally accompanied by hedonic sensations. This phenomenon, also known as (positive) affective touch, is likely to be the basis of affiliative interactions with conspecifics by promoting inter-individual bindings. Previous studies on healthy humans have demonstrated that affective touch can remarkably impact behavior. For instance, by administering the Rubber Hand Illusion (RHI) paradigm, the embodiment of a fake hand enhances after a slow, affective touch compared to a fast, neutral touch. However, results coming from this area are not univocal. In addition, there are no clues in the existing literature on the relationship between affective touch and the space around our body. To overcome these lacks, we carried out two separate experiments where participants underwent a RHI paradigm (Experiment 1) and a Visuo-Tactile Interaction task (Experiment 2), designed to tap into body representation and peripersonal space processing, respectively. In both experiments, an affective touch (CT-optimal, 3 cm/s) and neutral touch (CT-suboptimal, 18 cm/s) were delivered by the experimenter on the dorsal side of participants’ hand through a “skin to skin” contact. In Experiment 1, we did not find any modulation of body representation—not at behavioral nor at a physiological level—by affective touch. In Experiment 2, no visuo-tactile spatial modulation emerged depending upon the pleasantness of the touch received. These null findings are interpreted in the light of the current scientific context where the real nature of affective touch is often misguided, and they offer the possibility to pave the way for understanding the real effects of affective touch on body/space representation.

Keeping in Touch with Mental Health: The Orienting Reflex and Behavioral Outcomes from Calatonia

Physical and psychological therapy based on touch has been gradually integrated into broader mental health settings in the past two decades, evolving from a variety of psychodynamic, neurobiological and trauma-based approaches, as well as Eastern and spiritual philosophies and other integrative and converging systems. Nevertheless, with the exception of a limited number of well-known massage therapy techniques, only a few structured protocols of touch therapy have been standardized and researched to date. This article describes a well-defined protocol of touch therapy in the context of psychotherapy-the Calatonia technique-which engages the orienting reflex. The orienting reflex hypothesis is explored here as one of the elements of this technique that helps to decrease states of hypervigilance and chronic startle reactivity (startle and defensive reflexes) and restore positive motivational and appetitive states.