Why inflammation and the activities of the immune system matter for social and personality psychology (and not only for those who study health)

Abstract A growing body of research finds that the activities of the immune system—in addition to protecting the body from infection and injury—also influence how we think, feel, and behave. Although research on the relationship between the immune system and psychological and behavioral outcomes has most commonly focused on the experiences of those who are ill or experiencing an acute immune response, we propose that the immune system may also play a key role in influencing such outcomes in those who are healthy. Here, we review theory and research suggesting that inflammation—a key component of the immune response to pathogens and stressors—may play an important modulatory role in shaping emotions, motivation, cognition, and behavior, even among those without symptoms of illness. Moreover, because inflammation occurs in response to a number of everyday social experiences (e.g., loneliness and stress), we propose that it may be an important mediator of many psychological and behavioral outcomes that are of interest to social and personality psychologists. We close by discussing potential opportunities for researchers looking to incorporate psychoneuroimmunology (PNI) into their area of inquiry.