Social engagement with the physician should engender trust and alleviate unrealistic anxiety. Porges8 has extended Engel's findings and identified 3 well-defined, hierarchically organized, neural circuits linked to the evolution of the autonomic nervous system that evolved to gauge environment risk and regulate human adaptive behavior in response to safe, dangerous, or life-threatening situations.8 Two neuropeptides, oxytocin and arginine vasopressin, are intimately linked to these neural circuits.9 In this neurophysiological model, when the social environment is deemed safe and trustworthy, the patient establishes eye contact with the examiner, listens intently to what is said, and breathes freely; the heart rate is rhythmically synchronized with breathing—increasing during inspiration and decreasing during expiration. This synchronization results from the activation of the myelinated vagus nerve that innervates the lungs and heart and is linked to neural regulation of the facial muscles of emotional expression and the middle ear muscles that extract human voice. When threatened, social engagement is abandoned and the patient becomes hypervigilant, respiration and heart rate increase, and the sympathetic nervous system is engaged (fight or flight). When despairing (Engel's conservation withdrawal), the patient becomes listless then dissociated, physiologic and immune systems begin to disengage, and gastrointestinal symptoms and bradycardia ensue with the activation of the phylogenetically primitive unmyelinated vagus nerve fibers that innervate these structures. If the physician attends to the signs of hopelessness, fear, and emotional disengagement, this primitive giving up response can be averted.