In this study, event-related brain potentials (ERPs) are used to measure subjects' responses to violations of musical expectancies elicited in seventone sequences. We manipulated the structure of the sequence (strongly vs. weakly constraining), the congruity of the terminal tone (congruent vs. incongruent), the form of sequence presentation (both types intermixed vs. blocked), and subjects' musical training. The degree of expectancy violation was measured by the P300 component of the ERP known to be sensitive to subject's expectations. As predicted, musically trained subjects generate specific expectancies in strongly constraining sequences. Expectancies may also be generated in weakly constraining sequences, however, only when these are intermixed among strongly constraining sequences. Otherwise, musically trained subjects refrain from expectancy generation and rely on their knowledge of the structure of musical scales. Musically naive subjects respond, overall, slower and less accurately than trained subjects but show similar overt behavioral effects, suggesting that these differences reflect only varying degrees of processing efficacy. ERP data, on the other hand, suggest that processing differs significantly between musically trained and untrained subjects. One such difference is that musically naive subjects generate expectancies regardless of the level of constraints in the sequence.
- ©© Regents of the University of California