Geometric relationships across notes constitute a primitive in melodic processing

How do the notes included in a melody affect its processing? The interactions and relationships among collections of notes are surprisingly intricate, and their impact on perception is not well understood. Theoretical accounts have suggested that musical sets - the relational structures resulting from any collection of notes - constitute a critical aspect of music perception. However, empirical work which directly engages with this foundational construct remains limited. We introduce a simple behavioral protocol to test how musical sets, and their geometric structure, influence melodic sequence processing. Based on data collected from hundreds of participants across three experiments, we demonstrate that certain sets wholly alter our sensitivity to note deviations in melodies. We further show that geometric properties, including the uniformity of note distributions, capture these effects across a variety of musical structures. Altogether, our results firmly position musical sets as a primitive representation in melodic processing and uncover geometric measures that account for their role in music perception.