For the study, which was recently published in the British Journal of Psychiatry, Luhrmann and her colleagues interviewed 60 adults diagnosed with schizophrenia—20 each in San Mateo, California; Accra, Ghana; and Chennai, India. The patients were asked how many voices they heard, how often they heard them, and what the voices were like.

There were a number of cross-cultural similarities: Everyone from the Ghanians to the Californians reported hearing both good and bad voices and hearing unexplained hissing and whispering.

But there was one stark difference, as Stanford News points out: "While many of the African and Indian subjects registered predominantly positive experiences with their voices, not one American did. Rather, the U.S. subjects were more likely to report experiences as violent and hateful—and evidence of a sick condition."

The Americans tended to described their voices as violent—"like torturing people, to take their eye out with a fork, or cut someone's head and drink their blood, really nasty stuff," according to the study.

Meanwhile, the Indians and Africans were more likely to say that their hallucinations reminded them of friends and family, and that the voices were playful or even entertaining. "Mostly, the voices are good," said one Ghanian participant.

A Chennai participant said, "I have a companion to talk [to] . . . [laughs] I need not go out to speak. I can talk within myself!"

Luhrmann and her colleagues chalked up the differences in how the voices were perceived to distinct societal values. Americans desire individuality and independence, and the voices were seen as an intrusion into a self-made mind. Eastern and African cultures, meanwhile, tend to emphasize relationships and collectivism. There, a hallucination was more likely to be seen as just another point in the schizophrenic person's already extensive social network. In fact, the participants were sometimes so sympatico with their hallucinations that they didn't even see themselves as mentally ill:

Many in the Chennai and Accra samples seemed to experience their voices as people: the voice was that of a human the participant knew, such as a brother or a neighbor, or a human-like spirit whom the participant also knew. These respondents seemed to have real human relationships with the voices—sometimes even when they did not like them.

Luhrmann says she thinks her insights might help in the development of new therapies for schizophrenia sufferers the world over. There's no cure for schizophrenia, but some therapies urge patients to develop relationships with their hallucinated voices and to negotiate with them.

In an article for the American Scholar, Luhrmann describes one such patient, a 20-year-0ld Dutch man named Hans, whose inner voices were urging him to study Buddhism for hours each day. He cut a deal with his demons, telling them he'd say Buddhist prayers for one hour per day, no more, no less. And it worked—the voices subsided and he was able to taper his dose of psychosis medications.

At one support group for schizophrenic patients, Hans said a new, "nice" voice he had been hearing recently threatened to get mean.

"This new voice seemed like it might get nasty," Luhrmann writes. "The group had told [Hans] that he needed to talk to it. They said that he should say, 'We have to live with each other and we have to make the best of it, and we can do it only if we respect each other.' He did that, and this new voice became nice."