Emotional arousal when watching drama increases pain threshold and social bonding
R. I. M. Dunbar, Ben Teasdale, Jackie Thompson, Felix Budelmann, Sophie Duncan, Evert van Emde Boas, Laurie Maguire
Published 21 September 2016. DOI: 10.1098/rsos.160288
Fiction, whether in the form of storytelling or plays, has a particular attraction for us: we repeatedly return to it and are willing to invest money and time in doing so. Why this is so is an evolutionary enigma that has been surprisingly underexplored. We hypothesize that emotionally arousing drama, in particular, triggers the same neurobiological mechanism (the endorphin system, reflected in increased pain thresholds) that underpins anthropoid primate and human social bonding. We show that, compared to subjects who watch an emotionally neutral film, subjects who watch an emotionally arousing film have increased pain thresholds and an increased sense of group bonding.
Fiction, in the form of both storytelling and drama, is an important feature of human society, common to all cultures. Though widely studied in the humanities, the reasons why we become so engrossed in fiction, and the likely functions for this, have attracted very little attention from either psychologists or behavioural biologists. Yet, it is evident that people are willing to spend a great deal of time, and often money, to be entertained in this way, whether casually in social contexts or formally in the theatre or cinema, often incurring significant costs when doing so. Storytelling forms a major component of evening conversations around the campfire in hunter–gatherer societies . One important function is that it enables us to pass on, in the form of origin stories or a corpus of commonly held folktales and folk knowledge, the cultural ideologies that create a sense of community. Shared knowledge forms part of the mechanism that binds friends [2–5] as well as communities [6,7].
As important as these cognitive aspects of storytelling may be for community bonding, they do not explain why we are willing to return again and again to be entertained by storytellers and dramatists. One plausible explanation for our enjoyment of comedy might be that comedy makes us laugh, and laughter activates the endorphin system [8–11], thereby providing a sense of reward and pleasure. Endorphins act as analgesics and increase tolerance of pain , being responsible for well-known phenomena like the ‘runner's high’ . As a result, comedy that makes us laugh out loud results in an increase in pain threshold [8–10]. But why should we be just as engaged by emotionally stirring plots that ‘reduce us to tears’ (i.e. tragedies)? One possibility is that the emotional arousal triggered by such stories also activates the endorphin system, because the same areas of the brain that support or respond to physical pain are also involved in psychological pain [14–17]. There is now an extensive literature suggesting that social rejection or viewing emotionally valenced pictures, and even just musically induced mood change, elevate pain thresholds, thereby seeming to allow subjects to attenuate their responses to negative emotional experiences [18–22]. There is even some suggestion that watching a dramatic film increases pain threshold, albeit with small samples and somewhat mixed results [23,24].
While the cognitive component of social bonding is important in maintaining relationships through time in humans, primate social relationships and the bonding of social groups in humans, it is also underpinned by a psychopharmacological mechanism in what is effectively a dual mechanism process . Endorphins, while part of the brain's pain management system [12,26–29], also play a central role in social bonding in anthropoid primates [30–33]. This latter effect is mediated through the afferent c-tactile neural system  by the light stroking that occurs during social grooming, and PET imaging has confirmed that this behaviour activates the endorphin system in humans . It seems that a number of other social activities, including laughter , singing  and dancing , also activate this system and, through this, enhance the sense of bonding to the other individuals present.
We used live audiences to test the hypothesis that emotionally arousing film drama triggers an endorphin response (indexed by change in pain threshold) and, at the same time, increases the sense of belonging to the group (social bonding).