I have long suspected that it may be a brain hemispheres thing.

For most people (essentially all right-handed people and the majority of left-handers), language is primarily in the left brain. According to an article in the July 2009 Scientific American:

Thus, writing and designing tend to use different parts of the brain.

So how does music fit in?

Well… Until I started doing the research for this post, I had the impression that music is processed primarily in the right brain, and I was thinking that it thus competed with a left-brain activity (writing) and complemented a right-brain activity (designing). This idea is supported by various sources, such as the Encyclopedia of Psychology, which states: “While the left-brain hemisphere performs functions involving logic and language more efficiently, the right-brain hemisphere is more adept in the areas of music, art, and spatial relations.”

But it turns out that things are not that simple, and that piece from the Encyclopedia of Psychology is nine years old. I came across a lot of contradictory research findings, exemplified by the following:

• “Findings … revealed a high correlation between perception of musical ability and right brain function… .” (from the abstract of “Brain hemisphere dominance and vocational preference: A preliminary analysis”, 2007)
• “…these data contradict a strong hemispheric specificity for music perception, but indicate cross-hemisphere, fragmented neural substrates underlying local and global musical information processing in the melodic and temporal dimensions.” (from the abstract of “Receptive amusia: evidence for cross-hemispheric neural networks underlying music processing strategies”, 2000)
• “Our data suggest that musicians and non-musicians have different strategies to lateralize musical stimuli, with a delayed but marked right hemisphere lateralization during harmony perception in non-musicians and an attentive mode of listening contributing to a left hemisphere lateralization in musicians.” (from the abstract of “The cerebral haemodynamics of music perception” (PDF), 1999)
• Other findings showing differences between musicians and non-musicians, between men and women, and even between adults and children

But the kicker is Daniel Levitin’s work, as described in his book “This Is Your Brain on Music: The Science of an Obsession”:

So why do so many of us designers find it difficult to listen to music while we write but helpful while we design? The answer is apparently not as simple as I had imagined.

Oh well, there goes a nice hypothesis. (At least I know better than to call it a theory. But here comes a potential research project.

And oh, btw — I would never say that “mathematics” is in the left brain. Having a graduate degree in mathematics, I know all too well that it depends on what kind of mathematics. I would place computation primarily in the left brain, but would suggest that geometry, abstract algebra, and possibly number theory are solidly in the right brain. (I remember that after struggling with multivariate calculus — as left-brained an activity as ever there was — I felt a great sense of relief to get into abstract algebra and find it so fascinating I couldn’t wait to get back to the dorm to do the homework. But most of my classmates didn’t see it that way.)