Social interoception and social allostasis through touch: Legacy of the Somatovisceral Afference Model of Emotion.

John Cacioppo and colleagues' Somatovisceral Afference Model of Emotion (SAME) highlighted the importance of interoception in emotional experience. Here we compare how the SAME and the more recent theory of constructed emotion (TCE) view the role of interoceptive signals in creating emotional experiences. We describe the characteristics of touch sensations that are carried by thin, unmyelinated fibers called C-tactile afferents (CTs) to the posterior insula, and are thus deemed interoceptive despite their typically social (external) origin. We explore how this social interoceptive input might contribute to the emotion-related effects of social touch more generally, and speculate that all social touch, with or without CT afferent stimulation, can directly influence allostasis, or the predictive regulation of short- and long-term energy resources required by the body. Finally, we describe several features of CT-optimal touch that make it a potentially useful tool to help illuminate basic interoceptive mechanisms, emotion-related phenomena, and disorders involving atypical affect or somatosensation. These proposed ideas demonstrate the long intellectual reach of John Cacioppo and Gary Berntson's highly productive scientific collaboration, which was formative for the fields of social neuroscience, social psychophysiology, and affective neuroscience.