Kawakami and colleagues asked 44 volunteers, including both musicians and non-specialists, to listen to two pieces of sad music and one piece of happy music. Each participant was required to use a set of keywords to rate both their perception of the music and their own emotional state.
The sad pieces of music included Glinka's "La Séparation" in F minor and Blumenfeld's Etude "Sur Mer" in G minor. The happy music piece was Granados's Allegro de Concierto in G major. To control for the "happy" effect of major key, they also played the minor-key pieces in major key, and vice versa.
The researchers explained that sad music evoked contradictory emotions because the participants of the study tended to feel sad music to be more tragic, less romantic, and less blithe than they felt themselves while listening to it.
"In general, sad music induces sadness in listeners, and sadness is regarded as an unpleasant emotion. If sad music actually evokes only unpleasant emotions, we would not listen to it," the researchers wrote in the study.
"Music that is perceived as sad actually induces romantic emotion as well as sad emotion. And people, regardless of their musical training, experience this ambivalent emotion to listen to the sad music," added the researchers.
Also, unlike sadness in daily life, sadness experienced through art actually feels pleasant, possibly because the latter does not pose an actual threat to our safety. This could help people to deal with their negative emotions in daily life, concluded the authors.
"Emotion experienced by music has no direct danger or harm unlike the emotion experienced in everyday life. Therefore, we can even enjoy unpleasant emotion such as sadness. If we suffer from unpleasant emotion evoked through daily life, sad music might be helpful to alleviate negative emotion," they added.