At its core, a joke or a prank is funny because it defies expectations. That is, you predict a certain outcome and another happens instead requiring resolution by associating the unexpected outcome with an alternative meaning. This involves multiple brain areas.
Here’s an example:
“I haven’t slept for ten days…because that would be too long.” – Mitch Hedberg
If you found this funny, it’s because you anticipated it would follow a logical progression – that it’s been ten days since you last slept. You’re using your prefrontal cortex – where cognitive processing and pattern recognition occurs – to do this. But when you hear the punch line and the two incompatible thoughts are merged (not sleeping in the last ten days and sleeping for ten days), your brain activity shifts away from information processing toward an emotional response signaled by the nucleus accumbens. And the supplementary motor area coordinates the movements associated with laughter.
Impairment to these specific areas or the connections between them can dampen one’s ability to find things funny. This can result from stroke, brain injury or even psychiatric or psychological disorders. People who are depressed display decreased activity between the prefrontal cortex and the reward center where humor is processed. But the brain still responds to cues of amusement from the body – even if they are forced at first. So even if you don’t feel like laughing or can’t find the humor in a situation, the very act of smiling can improve how you feel.
The benefits of laughter are abundant. So if you hear a good joke today, enjoy a hearty laugh. It will brighten your day and probably someone else’s as well.