Seth Roberts has observed that doing two boring things simultaneously is a lot of fun. Unfortunately, I do most of my walking in Philadelphia, where it’s a bit dangerous to study Chinese flashcards at the same time. However, it’s occurred to me that the same theory might make predictions about the pleasurability of various art forms. Reading comics requires simultaneous comprehension of word and image; listening to popular music requires simultaneous comprehension of word and tone. In technical terms, the best comics writers and artists are not as good as the best novel-writers or visual artists; likewise, the best popular lyricists and musicians are not as good as the best poets or classical musicians. But these art forms are at least as vital as their (let’s call them) unimodal counterparts (prose, poetry, fine art, classical music).
You might be able to make the same argument work with TV and cinema, although an interesting difference is that cinema (at least) is a critically respected art form, whereas comics and popular music are mostly not. (TV is mostly not, and to my mind the best TV shares more with novels than with cinema.) To stretch it even further, you might try to explain the popularity of less-well-written genre fiction — e.g. poorly written science fiction is saved by the simultaneous task of understanding a novel-level (i.e. superficial) description of some technology, likewise poorly written epic fantasy and learning (at a relatively superficial level) about the setting and/or magic system the author has created. That might be a bridge too far, though — it seems reasonably likely that even the best-written novel is forcing the reader to keep track of many things at once.
One problem with this observation about art is that it isn’t obviously explained by Seth’s theory. If there is a theory behind it, it’s something along the lines of a flow state — i.e. something that would be boringly simple to do on its own is improved to just the right level of difficulty by the addition of another simple dual task. (Actually, there are probably ways to make Seth’s theory work for me, but I’m pressed for time.) If that form of the explanation is right, then it would suggest that comics and popular music actually select against virtuosic practitioners in single modalities (because simultaneously comprehending virtuosic art in two modalities is too hard), while unimodal art forms select for them. I’m using “virtuoso” in a fairly specific sense here — I certainly don’t mean that comics and pop music can never be any good, or that most people are too stupid to appreciate good work in those media. More that “good” may mean something surprisingly different in multimodal versus unimodal art. Another prediction of the flow theory is that appreciation of multimodal art may be influenced by working memory capacity. But I imagine that WMC has socioeconomic correlates that would make that hypothesis hard to test.