The mixture of pleasure and fear that people experience at Halloween, seeing a scary movie or taking a frightening roller-coaster ride reflects a human desire to navigate or manage emotion, says a Duke University expert on the history of emotion.

"While psychologists don't know why we enjoy certain frightening experiences, my suspicion is that these frightening experiences give us a chance to see how we might handle fear or violence," says William Reddy, professor of history and cultural anthropology. "It's a kind of practice run."

Reddy says ethnographic studies show that even though people in different cultures have varying ideas about what emotions are and use different vocabulary to describe them, they all are interested in shaping emotions and controlling others' emotions. This desire extends to frightening situations.

"It gives us a chance to simulate these kind of managerial tasks safely," he says.

In his book, "The Navigation of Feeling: A Framework for the History of Emotions," Reddy offers a new theory of emotions that draws upon research in anthropology and psychology.

"Generally what people do is try out an expression and hope that it clicks," he says. "Sometimes you say 'I love you' to your mother and you don't really feel it. But you say it because you want it to be the case. And often it works."

Reddy can be reached for additional comment at (919) 684-2497 or by email.