Just as our muscles atrophy with inactivity, our ability to connect with other human beings weakens if we spend too much time alone or engage them only via technologies like smart phones, according to Barbara L. Fredrickson, psychologist at the University of North Carolina, and her team of researchers. Social connection also enhances health. “When you share a smile or laugh with someone face to face, a discernible synchrony emerges between you, as your gestures and biochemistries, even your respective neural firings, come to mirror each other,” Fredrickson wrote. “It’s micro-moments like these, in which a wave of good feeling rolls through two brains and bodies at once, that build your capacity to empathize as well as to improve your health” (New York Times, March 23).