Christian F. Hempelmann's research is a barrel of laughs. Well, a village of laughs to be exact. On the 40th anniversary of the Tanganyika Laughter Epidemic of 1962, the Purdue University linguistics doctorate candidate began researching the mythicized event that claims to have paralyzed numerous towns for months while residents were consumed with insatiable laughter. But this yearlong plague of the giggles is no laughing matter. At this month's International Society for Humor Studies Conference at Northeastern Illinois University, Hempelmann argued that it was extensive stress, not bliss, that victimized thousands of residents in the African village. And in today's world of terrorism and 12-hour workdays, he said it could happen again.

Q. What is the popular concept of what happened in Tanganyika in 1962?

A. It started in a little boarding school in the village of Kashasha in what is now Tanzania, Africa. There was an initial event of laughter by a small group of students, possibly due to a joke. Eventually, the whole school was affected by the laughter by contagion. People take this at face value. One person laughs, then another person laughs, then it spreads like an avalanche. So when parents picked up their children from school, they started laughing. Then it spread to other villages, and so on. And depending on where you read about it, the laughing epidemic lasted for anywhere from six months to a year-and-a-half. The original report on the event has been misquoted and exaggerated.

Q. Sounds fun, but not credible. Is this even possible?

A. No. They weren't laughing continuously for a year. People ignore the physiology of laughter. No one can laugh for more than about 20 seconds because laughing is such a strain on respiration. You know when you laugh for so long that it starts to hurt? You just can't do it for that long. So it is impossible for an entire population to laugh for a year because it's impossible for one person to laugh for more than a minute.

Q. So is it all a myth?

A. Something did happen in Tanganyika. The bad news is, it had nothing to do with humor. There was no merriment. Laughter was one of many symptoms.

These people were showing anxiety-related symptoms, from pain, to fainting, to respiratory problems, and sometimes people get rashes. There were attacks of crying as well as laughing.

The incident did last for about a year, but it occurred in relapses, not constantly. It spread to a couple of other schools and another village. The school did close down. You can't know exactly how many people were affected, but it was around several thousand.

Q. What caused it?

A. It's called mass hysteria. This is when a certain behavior is observed in a group of people that is not related to a certain environmental stimulus. There is no specific cause.

Now we call it Mass Psychogenic Illness (MPI). It's psychogenic, meaning it is all in the minds of the people who showed the symptoms. It's not caused by an element in the environment, like food poisoning or a toxin. There is an underlying shared stress factor in the population. It usually occurs in a group of people who don't have a lot of power. MPI is a last resort for people of a low status. It's an easy way for them to express that something is wrong. That may be why it has come to be associated more often with women.

Q. Can something like this happen again?

A. It's more common than you think. It usually starts in a school or in a work place, when people are in a stressful situation and they don't have the power to get out of that situation.

In 1962, Tanganyika had just won its independence. The young people involved reported that they were feeling stressed by the higher expectations of their teachers and parents. It is a common occurrence and a costly occurrence if it occurs at your workplace because it may have to be closed down. This happened in Lafayette, Ind., a couple of years ago. They'll get someone to spray the area to comfort people who were involved. People will say that there were a bunch of bugs and we were all stung by it. They won't admit that it was hysteria.

Q. Will there be anymore research into the Tanganyika epidemic to develop ways to prevent a similar case in the future?

A. This case is dead. No good records were kept on it, so it's going to be hard to get reliable information. I'm going to try to go there to interview people who were there at the time. But the problem with studying MPI is that by the time authorities come in, it's over. It will always be a hard thing to witness.