At Montreal’s McGill University, neuropsychologist Robert Zatorre has a test that suggests a noticeable difference in musical cognition between musicians and non-musicians. “We play a tune in one key,” he explains, “and then repeat it at a different key, and ask if it’s the same or if a note has been changed. What we find is that people with musical training are inclined to do better. If you study people who don’t have training, you’ll find some people who are just as good as the musicians, but others who are just awful at it.”