Does Mozart make people significantly smarter? Many people have speculated about a “Mozart effect”—the possibility that listening to music by the classical composer stimulates the brain, thereby raising people’s performance on a variety of intellectual tasks. So is there really a Mozart effect? Specifically, is there a statistically significant effect—a difference between people who listen to Mozart and others that is greater than what would be expected by chance? To find out, researchers asked one group of people to listen to Mozart and another group to listen to a short story. Both groups then attempted some intelligence test items. A statistical test revealed no significant difference between the groups (Nantais & Schellenberg, 1999); on average, people who listened to Mozart did not perform significantly better or worse than others. This reveals an important virtue of statistical tests: They sometimes show that expected differences between groups are not statistically significant.