Shared Neural Mechanisms Underlying Social Warmth and Physical Warmth

Abstract

Many of people’s closest bonds grow out of socially warm exchanges and the warm feelings associated with being socially connected. Indeed, the neurobiological mechanisms underlying thermoregulation may be shared by those that regulate social warmth, the experience of feeling connected to other people. To test this possibility, we placed participants in a functional MRI scanner and asked them to (a) read socially warm and neutral messages from friends and family and (b) hold warm and neutral-temperature objects (a warm pack and a ball, respectively). Findings showed an overlap between physical and social warmth: Participants felt warmer after reading the positive (compared with neutral) messages and more connected after holding the warm pack (compared with the ball). In addition, neural activity during social warmth overlapped with neural activity during physical warmth in the ventral striatum and middle insula, but neural activity did not overlap during another pleasant task (soft touch). Together, these results suggest that a common neural mechanism underlies physical and social warmth.

Embodied motivation: Using a goal systems framework to understand the preference for social and physical warmth.

“…Inagaki and Eisenberger (2013) found that social warmth can make people feel physically warmer, which suggests that socially warm activities may effectively reduce physical coldness. Other research also hints at this possibility, suggesting that social warmth can be used as a buffer for physical coldness (Kolb et al, 2012;Zhou et al, 2012).…”

“…Similarly, Ijzerman and Semin (2009) found that participants seated in a warm room report feeling interpersonally closer to the experimenter than do those seated in a colder room. Conversely, experiencing social rejection makes people feel physically cold (IJzerman et al, 2012;Zhong & Leonardelli, 2008), experiencing social connection makes people feel physically warm (Hahn et al, 2012;Inagaki & Eisenberger, 2013), and thinking about a target's sociability traits increases estimates of room temperature (Szymkow et al, 2013).…”

Blocking opioids attenuates physical warmth-induced feelings of social connection.

“…Beyond mere metaphor, a growing body of research now suggests that changes to actual physical warmth can also affect perceptions of “social warmth,” feeling loved by and connected to others. For example, after holding warm objects, participants rated another person as interpersonally warmer (Williams & Bargh, 2008), reported feeling closer to other people (IJzerman & Semin, 2009), increased their trusting behavior (Kang, Williams, Clark, Gray, & Bargh, 2011), and felt more socially connected (Inagaki & Eisenberger, 2013). While these results suggest an overlap between experiences of social and physical warmth, the mechanisms, particularly the neurochemical mechanisms, linking these two concepts are unknown.…”

“…In addition, opioid-rich neural regions, such as the insula and ventral striatum (VS), show increased activity to innocuous physical warmth. For instance, participants asked to hold warm (vs. neutral) stimuli show increased activity in the insula (Becerra et al, 1999; Davis, Kwan, Crawley, & Mikulis, 1998; Inagaki & Eisenberger, 2013; Olausson, Charron, Marchand, Villemure, Strigo, & Bushnell, 2005; Rolls, Grabenhorst, & Parris, 2008; Verhagen, Kadohisa, & Rolls, 2004), and increases in self-reported pleasure in response to holding a warm stimulus are associated with increased ventral striatum activity (Rolls et al, 2008). …”

“…Moreover, viewing images of a loved one activates a number of opioid-rich regions, including the VS and mid-insula (Acevedo, Aron, Fisher, & Brown, 2012; Aron, Fisher, Mashek, Strong, Li, & Brown, 2005; Bartels & Zeki, 2000, 2004). Finally, in the first neuroimaging study to examine physical and social warmth together, the VS and mid-insula were the only two regions that showed overlapping neural activity between the two tasks (Inagaki & Eisenberger, 2013). Together, these studies suggest that opioids may be a critical neurochemical substrate underlying physical and social warmth and may contribute to the feelings of connection that come from physical warmth.…”