What do you get when you cross a television comedy with a brain scanner? A team led by Joseph Moran and William Kelley at Dartmouth College's Center for Cognitive Neuroscience tried to find out. The researchers used functional magnetic resonance imaging (fMRI) on subjects watching episodes of either Seinfeld or The Simpsons. The resulting scans showed that "getting" a joke occurs in specific brain regions different from those involved in finding it funny.

This dissociation between the cognitive and emotional parts of humor supports the scant previous research on humor's neural underpinnings, but the current study is the first to test the kind of humor people often experience in real life. "The idea of using sitcoms is very nice," comments Vinod Goel, a psychologist at York University in Toronto, noting that they are funnier than the puns and lawyer jokes he has used in his neuroimaging research.

An important feature of the Dartmouth study was that it neither asked the subjects to express what was funny nor tracked laughter or other overt physiological responses. Watching the shows in isolation, subjects weren't exactly busting a gut anyway, says Kelley—a good thing, because raucous laughter might have caused too much head movement for accurate fMRI readings. Asking subjects what was funny, Kelley believes, may have tainted the results of some earlier humor studies. After all, filling out a form or even just thinking about whether something is funny isn't the same as experiencing the pure joy of humor.

"The real trick is how, in the absence of laughter, do you assess humor?" Kelley says. The solution: rather than comparing individual responses with various points in the episodes, Kelley and his team simply assumed that the moments corresponding to the laugh track (or when an audience in a prior viewing laughed) were, on average, funnier than other parts of the episode. In analyzing the scans, they also assumed that humor detection comes just before humor appreciation.

The investigators found that instances of humor detection lit up the left inferior frontal and posterior temporal cortices—the left side of the brain. Humor appreciation, in contrast, led to spikes in activity in the emotional areas deeper inside—specifically, in the bilateral regions of the insular cortex and the amygdala.

Kelley believes that these results make sense. Past research has shown the left inferior frontal cortex to be involved in reconciling ambiguous meanings with prior knowledge. And ambiguity, incongruity and surprise are key elements in many jokes.

Kelley is the first to admit that his is just a preliminary study. Whereas the Dartmouth study assumed that humor detection comes just before humor appreciation, Goel points out that that sequence doesn't always hold true in his current research with single-panel comic strips. And although the laugh track seemed to be a reasonable rule of thumb in the Dartmouth work, that may be only because the subjects had been prescreened to like the cerebral, ironic style of the sitcoms they viewed.

"One of the biggest things that our study does is lead us to more questions," Kelley asserts. Future brain research could investigate whether these results extend to other types of humor, such as slapstick. But does the sitcom study at least help to explain why some people never seem to think a joke is funny, even when they clearly get it? "The individual-differences question is an interesting one," says Goel, but he argues that nonneurological explanations are more apt at this point. "If some people don't find The Simpsons funny, it's premature to say that they have a defective frontal lobe."

COPYRIGHT 2004 © Marina Krakovsky. All Rights Reserved.