It’s not clear where exactly ideas come from, but it is clear that they come more readily after exercise. Writing in the New York Times, Gretchen Reynolds directs us to research conducted at Stanford University that required students to sit while they took tests of creativity, which involved finding alternative uses for an object. The same students then took a similar test while walking on a treadmill. Reynolds reports that “for almost every student, creativity increased substantially when they walked. Most were able to generate about 60 percent more uses for an object.” Next, the researchers gave a creativity test to one group of students after they had gone for walk on a treadmill and to another group that had not walked. Yes, you guessed it. Reynolds tell us that “walking markedly improved people’s ability to generate creative ideas, even when they sat down after the walk. In that case, the volunteers who had walked produced significantly more and subjectively better ideas than in their pre-exercise testing period.” And now the surprising part: when the researchers asked the students to walk outside rather than inside, they found that the clean air and blue sky of the Stanford campus had no influence on creativity. The outside walk left students no more creative than did walking on a treadmill. Read more in the New York Times.