Event-Related Potentials to Expectancy Violation in Musical Context

Abstract

The present study addressed neuronal processing of musical tones that violate expectancies primed by auditorily and visually presented musical material. Event-related brain potentials (ERPs) were recorded while the musically trained subjects were presented with short melodies composed for the experiment. The subject's expectations for the most likely ending were strengthened by displaying the melody score on a computer screen simultaneously with its auditory presentation. In about half of the melodies, the expected ending was randomly replaced by a tone violating the subjective expectancies in physical (frequency) and cognitive (harmonic) dimensions. The present ERP results indicate that the melodic expectations cover the tone pitch as well as its harmonic function. At least with highly repetitive melodies when the listener is provided with simultaneous visual information of the expected ending of the melody, the expectations are predominantly formed in the physical dimension: Significant effects of expectancy violation were found in N1, N2, P3, and N4 ERP deflections for physically most distant but harmonically best fitting ending tone. In addition to physical distance between the expected and unexpected ending tone, harmonic context of the given melody modulated N2 deflection already at 200 ms after the unexpected ending.