In a just completed study, researchers at Northwestern University found that people were more likely to solve word puzzles with sudden insight when they were amused, having just seen a short comedy routine. “What we think is happening,” said Mark Beeman, a neuroscientist who conducted the study with Karuna Subramaniam, a graduate student, “is that the humor, this positive mood, is lowering the brain’s threshold for detecting weaker or more remote connections” to solve puzzles. ... The very idea of doing a crossword or a Sudoku puzzle typically shifts the brain into an open, playful state that is itself a pleasing escape.