In the 2000 film "Cast Away," Tom Hanks plays an obsessive, clock-watching businessman, Chuck Noland, who by a twist of fate finds himself stranded on an isolated Pacific island. Noland copes with his four years of social disconnection and loneliness in part by befriending a volleyball, which he names Wilson. He jokes with Wilson and confides in Wilson and mistreats Wilson, and at one point he even kicks his companion out of their cave like an angry spouse. When he finally and irretrievably loses his volleyball to the ocean currents, he cries, "I'm sorry, Wilson!"

We've all had fantasies about living alone on a tropical island, far from the din and pressure of modern life. But we should watch what we wish for, because in fact most of us would fare poorly in such isolated conditions. This has been shown time and again: people who live lonely and disconnected lives, even smack in the middle of a modern metropolis, are more depressed, more suicidal and have more physical illnesses than the rest of us. Such longing is especially poignant at holiday time. The lonely are in effect emotional castaways.

And how do emotional castaways cope? What cognitive tools do we have to salve the pain of loneliness? Psychologists are very interested in this question, and one emerging theory is that we do precisely what Chuck Noland knew intuitively to do. We "invent" people to keep us company, humanizing anything we can humanize—pets, supernatural beings, possibly even something as unlikely as a volleyball.

A team of psychologists recently decided to explore the "volleyball hypothesis" in the laboratory. Nicholas Epley, Adam Waytz and John Cacioppo of the University of Chicago and Scott Akalis of Harvard ran three different studies on the link between loneliness and anthropomorphism—the tendency to give human traits to nonhuman things like terriers and alarm clocks. Their findings shed some new light not only on human coping but on the unfortunate human tendency to dehumanize strangers.

The psychologists began by sorting out people who consider themselves chronically lonely from those who feel they are well connected with friends and family. In the first study, they introduced both the lonely and the connected to a few technological gadgets: For example, "Clocky" is a wheeled alarm clock that you must chase around the room in order to stop its ringing. "Pillow mate" is a torso-shaped pillow that can be programmed to give hugs.

Participants then rated each gadget on such traits as: "has a mind of its own" and "exercises free will" and "experiences emotions." They also rated each on nonhuman traits like efficiency and attractiveness.