"During the 1960s, researchers at Cornell University conducted a series of tests on the effects of working with music. They polled a group of computer science students and divided the students into two groups, those who liked to have music in the background while they worked (studied) and those who did not. Then they put half of each group together in a silent room, and the other half of each group in a different room equipped with earphones and a musical selection.Participants in both rooms were given a Fortran programming problem to work out from specification. To no one's surprise, participants in the two rooms performed about the same in speed and accuracy of programming. As any kid who does his arithmetic homework with the music on knows, the part of the brain required for arithmetic and related logic is unbothered by music —there's another brain center that listens to the music. The Cornell experiment, however, contained a hidden wild card. The specification required that an output data stream be formed through a series of manipulations on numbers in the input data stream. For example, participants had to shift each number two digits to the left and then divide by one hundred and so on, perhaps completing a dozen operations in total. Although the specification never said it, the net effect of all the operations was that each output number was necessarily equal to its input number. Some people realized this and others did not. Of those who figured it out, the overwhelming majority came from the quiet room."

(I hope this still counts as fair-use)

The whole part "Creative Space" is longer than my excerpt, so if you have access to Peopleware I recommend reading all of it.

You could reason that if you engage the brain with something, then it cannot do another thing at the same time. So if you engage the areas responsible for creative thought processes, these areas will not be available for other tasks.

Obviously this might not be the same for everyone, I'm just cautioning people and urging everyone to do some testing.

Another example is that many people (including myself) can't dictate, for the same reasons. In my case, whenever I use dictation, I later go back and re-read what I wrote and it is always disappointing. It seems the areas of my brain that process speech are also needed to form thoughts into sentences and I just can't do both well.