John T. Cacioppo, a psychologist who studies loneliness and directs the Center for Cognitive and Social Neuroscience at the University of Chicago, recently told The Wall Street Journal that the rate of loneliness in America has doubled in the past few decades, up from 11 percent in the 1980s to around 40 percent in 2010. Other research, conducted by the AARP and Harris Polling, puts this number at between 30 and 35 percent for regular loneliness and as high as 72 percent for occasional loneliness.