On the Oxford University Press blog (link), [Link checked on 3-08-2024.] Professor Si-Liu Tan reports on an experiment she ran with collaborators Matthew Spackman and Elizabeth Wakefield. They used a scene from Minority Report (2002) in which the two lead characters are in a mall attempting to evade the police while "Moon River" is played softly (so it would seem to be diegetic, coming from the mall's sound system). The researchers re-recorded "Moon River" to play louder and more crisply, trying thereby to simulate non-diegetic music. As a foil to that, they also played non-diegetic generic chase music.
Experiment participants listened to these different versions. Questions focused on the relationship between the two characters, and results showed surprisingly different reactions to "Moon River" depending on its presumed diegetic or non-diegetic status.
Professor Tan says it was
not our intention to draw any grand conclusions about the definitive and predictable effects of diegetic versus nondiegetic music. . . . The specific effects of migrating a piece of music from diegetic to nondiegetic depend on the unique interplay of music and moving images. However, our study suggests that the diegetic/nondiegetic distinction is perceptually salient to a general film audience. In some cases, it may lead to dramatically different perceptions of the tension of a scene, the attitudes, motives, and relationships of characters, and other judgments fundamental to one’s understanding of the unfolding film narrative.
