Tuesday, 20 December 2011

A Grain of Salt

Studying music makes you smarter, right?  If you believe every research study that’s ever been done, music training increases your IQ, makes you better at math, enhances verbal memory, general verbal ability and non-verbal reasoning, improves fine-motor control and motor learning, increases vocabulary and reading ability, enhances visuospatial cognition, and improves executive function.

Musicians, especially classically trained musicians, are generally thought to be smart.  And music and math “go together” so that people who are good at one are good at the other.  These ideas are so frequently touted that many people just assume they are true, without really looking at the evidence.

There have a been a fair number of research studies looking at the question of how musical training affects other abilities.  What I’d like to make clear today is that not all studies are created equal. 

How would you study it?
Imagine you want to test the hypothesis that studying music increases your IQ.  There are two main types of study that you could use.  The first (and weaker) type of study is correlational. Usually the study works something like this:  you would recruit a group of people with musical training (often university students studying music), and a second control group of people with no musical training.  Both groups take an intelligence test.  You expect that the group with musical training would be found to be smarter, and if they are, the conclusion would be that musical training increases your IQ.

Correlation and causation
But have you really shown that?  Correlational studies like this should have an important disclaimer:  the study doesn’t actually prove that musical training makes you smarter.  Scientists like to say that “correlation does not imply causation”.  What this means is that a correlational study shows only that:  a correlation.  The study shows that there is some kind of relationship between musical training and increased intelligence, but it doesn’t show what that relationship is.  There are several possibilities:
1)  Musical training makes you smarter
2)  People who are smarter are more likely to take and continue with musical studies
3)  Both musical training and increased intelligence are caused by some third unknown variable (such as family income, or competitive personality, or strong parental support).

Do you see how correlational studies are kind of weak?  There are a lot of studies in the literature that are conducted this way, because it’s easy to do.  But the studies don’t necessarily tell us all that much.

Longitudinal studies
So what is the better way to do this study?  The second type of research study you could do is a longitudinal study.  This type of study takes two groups of people and follows them over time to see how musical training alters other skills.  You would recruit people for the study and divide them into two groups.  One group would receive music instruction and one group would not.  You give the subjects an IQ test at the beginning and end of the music instruction, which goes for a defined period of time.  Ideally there would be no difference in test scores between the two groups at the beginning of the study, but at the end of the study, the group with musical training would outperform the control group.  The conclusion would be that the musical training has caused the difference in performance on the test, and this would be a much stronger and believable conclusion.

Dividing up the groups
There are a number of issues to consider in this type of study.  The first is:  how are the participants divided into the two groups?  There are different ways of doing this.  One way is to divide them completely randomly, which might seem like it would be the best, but what if you accidentally ended up with all the smartest people in one group?  Then you would find a difference in IQ before you even started the experiment, and that would make your study kind of useless.  If you have a large number of participants in your study, you're probably okay with a random division into groups, because chances are it will work out okay, but if you have a small number of people, you need to be careful about this.

Another option is completely non-random:  you recruit a group of people who were about to start receiving musical training anyway, and then you recruit a group of control people who match them first group in IQ.  This option has the advantage that you don’t have to give the musical training; the subjects were already going to do that.  Of course, the disadvantage here is that by taking away the randomness, you may be preselecting people in your musical training group that have some other variable you can’t control for.  For example, maybe the people in the musical training group have a higher income, which is why they can afford music lessons, and this may affect the way intelligence develops over the course of the study.

The third option is called pseudo-random.  You recruit people, give them the initial intelligence test, and then divide them into two groups in such a way that the two groups are evenly matched for initial intelligence, and also matched for other variables like age, family income, etc.

No matter how you split up your groups, there are other problems to be overcome with this type of study.  The main one is a kind of trade-off.  You want the study to run for as long as possible to ensure the biggest difference between the two groups.  If you only give one week of musical training, you’re less likely to find an effect on IQ.  But if the study runs for too long, you run into other difficulties. First of all, it’s expensive because you have to provide music lessons for all that time.  And second, you start running into problems where people drop out of the study, usually from the group receiving music instruction.  People do drop out of music lessons; it’s a big investment in time and not everybody is willing to make the commitment to daily practice, once they see how much work is involved.  So you have fewer people in your music-training group.  You might think this is not a big deal, but there’s another issue here.  If people who are less inclined to study music drop out, then you are left with people who naturally more inclined to study music.  Maybe these people are more intelligent to start with.  Or there is some other factor (like level of parental support) that could contribute to both continuing with musical training and also increased intelligence.  You see?  If too many people drop out, you lose your randomness.

The Bottom Line
I hope this discussion gives you some perspective on studies about the effects of musical training.  It’s actually hard to design and implement a really good study.  But then, what effect does musical training really have?  What can we believe from all the research that is out there?

I’ll discuss this research more in future posts, but it seems to me that there is pretty clear evidence that musical training improves verbal abilities, probably because music and speech both involve auditory parts of the brain.  And improved verbal abilities enhance reading skills.  A recent study also showed that musical training improved executive function in children.  I haven’t seen any good evidence that musical training improves math or spatial skills.  As for overall IQ, some studies have shown that musical training increases IQ, but some have not seen this increase, so I conclude that the effect is probably quite small.

Does studying music make you smarter?  Maybe a little.


  1. This article is wonderful as it helps me to get the sort of information that i needed.I am thankful as i got your article when was searching iq

  2. Nice blog post, and website! If I ever need to do a real study of something musical, I'll know who to get help from.

    I have a lot of articles on my blog that someone like you would probably find interesting. Here are three articles in particular:

    http://blog.twedt.com/archives/1365 (Questions the conclusions of a musical study about performance attire)

    http://blog.twedt.com/archives/64 (books like the ones mentioned in your post are discussed a bit in the beginning)

    http://blog.twedt.com/archives/1236 ("The Genetic Basis of Talent")