Why do we like sad music?

The Sunday New York Times has an interesting article by Professor Ai Kawakami describing a study on listeners' reactions to music the author characterizes as sad. The conclusion — that there is a disconnect between the emotion we feel while listening and the emotional content we think a piece music expresses — may have a certain plausibility, but I can't believe these researchers have ever listened to music. Consider the methodology:

A participant would listen to an excerpt and then answer a question about his felt emotions: “How did you feel when listening to this music?” Then he would listen to a “happy” version of the excerpt — i.e., transposed into the major key — and answer the same question. Next he would listen to the excerpt, again in both sad and happy versions, each time answering a question about other listeners that was designed to elicit perceived emotion: “How would normal people feel when listening to this music?”

Our participants answered each question by rating 62 emotion-related descriptive words and phrases — from happy to sad, from bouncy to solemn, from heroic to wistful — on a scale from 0 (not at all) to 4 (very much).

Who ever listens to music in this way? I rarely talk about my own reactions to music in emotional terms, but my response, especially with longer pieces, depends long-term direction. In other words, the one moment of ecstasy (no jokes, please) grows out of everything that has come before it, as well as the mood I bring to it. I don’t see how much emotion I could experience listening to one excerpt after another in a clinical setting. It would be too much like taking a test, and nothing like an aesthetic encounter. After a while, and not a very long while, I’d stop feeling anything at all.

And how unstable would a listener have to be to shift mood every few minutes just because the music changed? "Now I feel happy! Now I feel sad!" The music used in the study — Glinka’s “La Séparation” (F minor), Felix Blumenfeld’s “Sur Mer” (G minor) and Enrique Granados’s “Allegro de Concierto” (in C sharp major and G major versions — must have been extraordinary if it could flip emotions on and off like a light switch. I've got to get me some of that.