We all know that when we're in a bad mood, a joke can temporarily lift our spirits. But Dutch researchers set out to figure out precisely why. And although you may think, as many researchers do, that it's because positive emotions counteract negative ones — the researchers set out to prove that it's more than that.

They showed a group of men and women a series of pictures. First, they were shown negative images, and then two kinds of positive stimuli — funny and nonfunny. More people said that their moods were lifted by the funny stimuli (the jokes) than the merely positive stimuli.

The reason, according to the researchers, is in the actual cognitive work it takes for us to "get" a joke. Take this joke, for example. A terrified father calls a doctor and tells him, "Doctor, my child just swallowed a fountain pen!" When the doctor tells him he'll rush right over and asks, "What are you doing in the meantime?" The father replies: "Using a pencil."

Figuring out the punch-line is the kind of distraction that can make us feel better. "What they are suggesting is that humor," says Ed Dunkelblau, PhD, a psychologist and past president of the Association for Applied and Therapeutic Humor, "is an effective way to redirect anxiety."

So let's toast to (corny) jokes that make our brains work a little harder!