The soothing function of touch: experimental and neuroimaging studies

ocial bonding and support are important for human wellbeing. Close social bonds have long been known to serve safety and distress-alleviating functions. Interestingly, evidence from non-human mammals suggests that it is not the mere presence of conspecifics but rather certain active behaviours that are important for affective regulation. However, little is known about how active interpersonal supportive behaviours can buffer physical and psychological threat (e.g., pain) in human mammals. Recent evidence suggests that a specific type of dynamic, low-pressure touch that is associated with the activation of a particular type of peripheral touch receptor may be a particularly effective form of active social support. This type of touch is termed affective touch and this thesis aimed to examine its role on the social buffering of pain. Three experimental studies examined the modulatory role of affective touch on different forms of bodily and psychological threat, including social pain due to ostracism (Study 1), physical pain delivered by a laser device (Study 2), and the immediate space surrounding the body critical for triggering defensive reactions in the face of threat (Study 3). Given that the perception of bodily threat depends on prior beliefs about interpersonal relating, we examined whether the effects in study 2 and 3 were moderated by attachment style. On this basis, one experimental study also examined whether sensitivity to affective touch itself depends on individual differences in attachment style (Study 4). A fifth study presented a novel way to assess affective touch accuracy and meta-cognitive awareness (Study 5). Findings suggest that affective touch is a potent form of active social support, capable of attenuating pain. However, such effects were moderated by attachment style and depend on social context. Findings are discussed within a recent, Bayesian predictive coding theory of brain function, namely the Free Energy Principle, that allows to put forward a unifying model of bottom-up and top-down determinants of pain and affective touch, while emphasizing the interdependence of perception, action and relevance of social factors