psychotherapy:

…in recent years some researchers have begun to focus on a different, often more subtle kind of wordless communication: physical contact. Momentary touches, they say — whether an exuberant high five, a warm hand on the shoulder, or a creepy touch to the arm — can communicate an even wider range of emotion than gestures or expressions, and sometimes do so more quickly and accurately than words.

“It is the first language we learn,” said Dacher Keltner, a professor of psychology at the University of California, Berkeley, and the author of “Born to Be Good: The Science of a Meaningful Life” (Norton, 2009), and remains, he said, “our richest means of emotional expression” throughout life.

The evidence that such messages can lead to clear, almost immediate changes in how people think and behave is accumulating fast. Students who received a supportive touch on the back or arm from a teacher were nearly twice as likely to volunteer in class as those who did not, studies have found. A sympathetic touch from a doctor leaves people with the impression that the visit lasted twice as long, compared with estimates from people who were untouched. Research by Tiffany Field of the Touch Research Institute in Miami has found that a massage from a loved one can not only ease pain but also soothe depression and strengthen a relationship.

In a series of experiments led by Matthew Hertenstein, a psychologist at DePauw University in Indiana, volunteers tried to communicate a list of emotions by touching a blindfolded stranger. The participants were able to communicate eight distinct emotions, from gratitude to disgust to love, some with about 70 percent accuracy.

“We used to think that touch only served to intensify communicated emotions,” Dr. Hertenstein said. Now it turns out to be “a much more differentiated signaling system than we had imagined.”