Joseph A. DeVito, The Interpersonal Communication Book, Fourth Edition, 1986, Harper & Row

Touch also serves a primary role in consoling another individual. For example, we put our arms around people, hold their head in our hands, hold their hands, or hug them in an attempt to empathize with them more fully. It seems like an attempt to feel what the other person is feeling by becoming one with them--perhaps the ideal in empathic understanding. Try to console someone, even in role playing, when you are not allowed to touch them, and you will see how unnatural it seems and how difficult it is to say the appropriate words.