UC San Diego

As inextricably social beings, humans harbor (perceptions of) quality social connection as a vital homeostatic need. Our evolved fundamental need to belong drives much of our emotion, perception, and cognition, since quality social connection is required for optimal physiological and psychological functioning.Research on loneliness—perceived social isolation—reveals widespread physiological degradation and increased mortality risk when loneliness persists, situating social connection as a core component of psychosocial health. Loneliness, pervasive and dangerous, is a growing public health concern, yet it has proven difficult to ameliorate. Loneliness underlies many illnesses and more research on its mechanisms and frailties is urgently needed. Research on interoception—perception, regulation, and appraisal of bodily states—has recently surged driven by recognition of interoceptive mechanisms supporting emotional clarity, with promise of improving clinical disorders and psychosocial health. The burgeoning field of “social interoception” has just begun to examine interoception in loneliness, and our research represents some of the first studies on interoceptive mechanisms supporting social connection. However, what comprises perceptions of connection? Does quality social connection depend, in part, on a sense of intra-personal integration, clarity, or “connection”? This dissertation addresses these questions by focusing on a range of intra-personal and interoceptive mechanisms supporting social connection.

Chapter 1 assesses how different types of comparisons—intra-personal and social—impact perceptions of loneliness, using mixed methodology across diverse populations. Chapter 2 investigates physiological responses in loneliness using facial electromyography (fEMG) to assess spontaneous smiling and frowning activity during emotional perception. Chapter 3 addresses intra-personal affective correlates of loneliness using meta-analysis on 17 samples of cross-sectional survey data, highlighting the role of interoceptive body trust.

Altogether, this dissertation indicates that the common experience of loneliness is associated with maladaptive social cognition, behavior, and emotional processing. Interoception may represent “intra-personal connection” which impacts perceptions and fulfillment of quality social connection. Further investigations of interoception in affective social neuroscience, clinical psychology, and social connection will benefit from this research.