Mozart's Sonata for Two Pianos in D Major (KV 448) is one of the most used compositions in music psychology research. Since the publication of the study Music and Spatial Task Performance in Nature in 1993, numerous researchers have tried to replicate the so-called "Mozart effect" using this composition. And often with little success. The idea is of course compelling: to become smarter by simply listening to Mozart's music. It could be a helpful fact in the much needed support for a more prominent place of music in the curricula. However, the effect has been shown to appear not only with the music of Mozart, but also that of Beethoven, Sibelius, and even a 'Blur effect' was shown (based on a study by Glenn Schellenberg from the University of Toronto using 8,000 teenagers).

Currently, the most likely interpretation of the effect is that music listening can have a positive effect on our cognitive abilities when the music is enjoyed by the listener. Apparently (and in a way unfortunately), it is not so much the structure of the music that causes the effect, but a change in the mood of the listener. While this indirectness might be disappointing for admirers of Mozart's music, it is important to note that, at the same time, it leaves uncovered an important aspect of music appreciation. What makes certain music so effective in changing or intensifying our mood? It seems that while we are all experienced and active users of music as a kind of mood regulator (widely ranging from energizer to consoler of grief), music research has only just begun to explore the how and why of the relation between music and emotion.