If you’ve had a lot of musical training, you can probably tell the difference between a major and minor key. If you haven’t had much training, even after having the difference explained to you, you’re still not likely to be able to make that determination. Listen the following clip. It plays the same melody in a major and a minor key. Can you tell which is which?
But if the question is phrased differently, even non-musicians can reliably tell the difference: When listeners are told that some music (which happens to be in a major key) sounds “happy” and other music (in a minor key) sounds “sad,” non-musicians can pick out the difference. With that information in mind, do you want to change your answer about the two samples above? If you do, you’re probably a non-musician. If you don’t, you either got lucky in your answer, or you are a musician. Either way, it’s clear that musicians process “major” and “minor” differently from non-musicians. So what’s different about the mental processing of musicians and non-musicians?
A team led by Andrea Halpern created 35 short tunes like the clips above. Each tune was then modified to have a minor-key and major-key variant — this involved changing just a few notes in each tune. Then three expert musicians rated each clip for musicality and how “major” or “minor” each clip sounded. The 24 best examples of tunes with readily-identifiable major and minor keys were selected for study.
The researchers then played the clips for 18 musicians, with over 8 years of musical training, and 18 non-musicians, with less than 6 months of training. The listeners were first briefly trained either to recognize major/minor keys or “happy” and “sad” music. Several examples of each type were played, and then for seven clips, the listeners were asked to identify whether it was major or minor (or happy or sad), and given feedback on whether their answers were correct.
Finally, they were tested on new clips, while wearing a cap which had 30 electrodes designed to measure electrical activity in the brain. The data was collected on an EEG device.
Regardless of whether they were trained to recognize happy and sad music or major and minor keys, the musicians were extremely accurate, averaging about 90 percent correct. But non-musicians had a different result:
When they were trained in the major-minor method, non-musicians averaged just 63 percent correct for tunes in a major key. What’s more, after the experiment, participants were asked what strategy they used to respond, and many non-musicians said they just listened for whether the music sounded happy or sad. Those who used this strategy averaged 75 percent accuracy, while the remainder who used no strategy were just 53 percent accurate — statistically no better than chance.
Meanhwile the musicians nearly all reported using a major/minor strategy, even when trained in the happy/sad approach. Interestingly, this result can be clearly seen in the data from the EEG:
This figure shows a topographic map of electrical activity from 500 – 600 milliseconds after the first diverging note played in a tune (e.g. the note that distinguishes a minor-key from a major-key). As you can see, regardless of the training they received, non-musicians’ brain activity doesn’t look much different for minor tunes and major tunes. But for musicians, again regardless of their training, there was a dramatic difference in activity in the temporal and parietal lobes of the brain (the lower back area of your head).
The researchers suggest that the lack of activity in musicians during major tunes may be due to the fact that most Western music is played in a major key: 97 percent of popular American songs, and 73 percent of classical music is in a major key. So the activity occurs when an relatively unexpected key is used — but only for trained musicians.
Halpern, A.R., Martin, J.S., Reed, T.D. (2008). An ERP Study of Major-Minor Classification in Melodies. Music Perception, 25(3), 181-191. DOI: 10.1525/mp.2008.25.3.181