Does mood affect the "Aha" moment?

Next time you're struggling with a blank spot in a crossword puzzle, have somebody tell you a joke.

Scientists at Northwestern University found that their study subjects were more likely to solve word puzzles quickly, in sudden flashes of insight, immediately after watching a funny video.

Sometimes problem-solving calls for analysis, intellect, a systematic trial-and-error approach. But all good detective fiction also highlights the intuitive moment, the leap of logic that originates deep inside the unconscious mind.

Neuroscientists often use puzzles to try and understand those light-bulb moments. A few of these now-famous studies are highlighted in this New York Times article, Tracing the Spark of Creative Problem-Solving.

In the Northwestern study, researchers observed brain images as subjects watched a timed puzzle unfold, and found that people tended to intuit the solutions faster if their moods were positive. Scientists believe that a joke or amusing video may cause the mind to "widen its attention, in effect making it more open to distraction," which may just ready your brain for the "aha" moment.

You can test your own insight here with this quick, interactive video puzzle at the NYTimes website.