Processing musical form: Behavioural and neurocognitive approaches

Abstract

Simple melodies and short instrumental pieces largely unfold within the temporal limits of working memory. Within short time-spans (typically from 10 to 15 s), listeners can either subsume form parts into higher-order units (chunking process) or perceive them as sequential, and processes like these can happen while listening or in immediate retrospect. This study investigates the listeners’ chunking abilities as well as their assessment of coherence using two eight-measure theme types in AABB and ABAB forms. Double-letter labels (AA and BB) mark pattern similarity, while two-letter labels (AB) indicate pattern contrast. We measured the event-related brain responses (ERPs) while non-musicians listened to musical themes in real-time. Immediately after presentation, each piece of music had to be evaluated as either sequential or non-sequential (hierarchical). The rating results showed that ABAB compared to AABB forms were significantly more often judged as non-sequential (hierarchical). Independent of form type the tendency to chunk form parts seemed stronger when two aspects coincided: when rhythmical contrast between A-parts and B-parts was high, and when melodic contour was upward-downward. In contrast, the event-related potentials were insensitive to mental chunking processes. They merely reflected the brain’s responses to pattern structure. An anterior negative shift (anterior N300) was observed for immediate (AA) as well as for non-immediate repetition (ABA, ABAB) of similar form parts, suggesting pattern matching at phrase onsets on the basis of rhythmical sameness. To our knowledge, this study is the first neurocognitive approach to musical form perception.