By Paul J. Rosch, M.D.

President, The American Institute of Stress
Clinical Professor of Medicine and Psychiatry
New York Medical College
Originally published in Health and Stress, the newsletter (November 2005) of The American Institute of Stress

We laugh at jokes or something we see when we expect one outcome and are suddenly surprised by another.

In movie thrillers, as tension and suspense start to peak, directors often break it up by inserting something unanticipated or comical that helps viewers get rid of pent-up feelings.

This is frequently followed by another buildup of anxiety and stress and the process is repeated. Comic relief allows us to cope with such conflicting or incompatible emotions and thoughts by providing a mental break and a feeling of comfort.

In embarrassing or threatening situations, laughter may serve as a conciliatory gesture or as a way to deflect anger, especially if the threatening person joins in. Some believe that laughter may have originated as a signal of shared relief at the passing of danger. Because it results in a sense of relaxation that inhibits fight-or-flight responses, it might also signify trust in others.

One cultural anthropologist proposes that the purpose of laughter is to develop and strengthen connections between people because, "Laughter occurs when people are comfortable with one another, when they feel open and free. And the more laughter, the more bonding within the group."

This "bonding-laughter-more-bonding" feedback loop, combined with a common desire not to be different from others, may help to explain why we are 30 times more likely to laugh when people are present (including watching TV) and why laughter is often contagious.

One study showed that even laughing gas (nitrous oxide), an anesthetic used to prevent pain, loses its punch when taken in solitude. Nitrous oxide dampens the nervous system, which reduces inhibitions and can produce a sense of euphoria that makes some people feel and act so silly and giddy that they laugh often.

The Culture of Laughter 

Some people tend to laugh at jokes or situations that focus on somebody else's stupidity, mistakes or misfortunes because it makes them feel superior. Studies show that dominant individuals like bosses and tribal chiefs use humor more than subordinates.

This helps them exercise power by controlling the emotional climate of the group, which is why workers are much more likely to laugh at a superior's joke even if they don't find it funny.

People don't laugh at the same things depending on their socio-cultural background and age. Toddlers, children, teens and adults show significant differences about what they feel is funny. When someone says, "That's not funny," they either mean that they didn't get the point or that they find it offensive.

Sexist and racist jokes can be repugnant to many who feel strongly about abolishing bigotry and prejudice. 

As noted, we are most likely to laugh at jokes and situations when we are suddenly surprised by a punch line or something that is totally unexpected. This may explain why someone can tickle you into hysterical laughter but, as Aristotle noted, you get no such response by tickling yourself in the same fashion in the identical spot.

Although most young children instinctively giggle when they are tickled, prolonged tickling has been called one of the worst medieval tortures ever devised.

A tickle has been assumed to cause laughter because it is a reflex response and whether you or someone else initiates this stimulus, the information sent through your spinal cord to the brain should be the same. However, for tickling to make you laugh, the brain apparently requires an element of surprise, just like a joke. 

Why this is so important remains a mystery and various types of tickling machines have been constructed to explore this. One researcher reported that when people believe a machine is tickling them they laugh just as hard, suggesting that personal contact is not essential.

Studying Laughter

Gelotologists, researchers who study the physiology of laughter, have also found that other interconnected structures in the brain, such as the amygdala, hippocampus and hypothalamus, may also be involved. The medial portion of the hypothalamus has been identified as a major contributor to the production of loud, uncontrollable laughter. 

Happy people tend to have more activity in the brain's left prefrontal cortex in response to stress while anxious, pessimistic persons typically respond with activity in the right prefrontal lobes that tends to persist longer and delays recovery from negative events.

One study found that an area of the frontal lobe was activated only when people thought a joke was funny. Another reported that people with damage to their frontal lobes were more likely to choose a wrong punch line to written jokes and didn't laugh or smile as much at humorous cartoons. 

The bottom line is that Norman Cousins' hypothesis about the healing power of laughter and optimism has received strong support from scientific studies and is now generally accepted by the medical community.

In 1978, at the age of 62 and despite the lack of a medical degree or any formal training, he was invited to join the UCLA School of Medicine as Professor of Medical Humanities. He continued his studies on the effect of humor and emotions on health and immune system function until his death in 1990.

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