Listeners Detect Deviant Beats Better in Musical Rhythm Contexts with Fewer Subdivision Levels: an MMN and Behavioral Study

Poster Session A - Saturday, April 13, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Julia Yu¹, Aditi Tuli¹, Naomi Shi Yan Gong¹, Takako Fujioka¹; ¹Stanford University

In rhythm perception, patterns with fewer subdivisions allow listeners to extract the underlying beat structure more easily via sequential processing, whereas increased levels of subdivisions require hierarchical processing. We hypothesized that different subdivision levels would influence listeners’ ability to detect deviant beats, as reflected in higher behavioral performance as well as a larger amplitude of mismatch negativity (MMN). We recorded EEG while participants passively listened to a variety of rhythms. Each 2/4 rhythm contained a prime part and subsequent steady beats. We used four different primes; (prime1) two quarter notes, (prime2) two 8th and one quarter note, (prime3) four 8th notes, and (prime4) a dotted 8th and a 16th note pattern twice repeated, where the subdivision level increased from one (prime1), two (prime2&3), to three (prime4). The subsequent pattern was always the same, consisting of three quarter notes in standard trials, or the final note occurring an 8th or 16th note earlier in deviant trials. Afterwards, participants also determined whether two rhythms were the same or different. The MMN was primarily evident in the frontocentral electrodes. Deviant 8th elicited a significantly larger MMN than deviant 16th across all primes. Behaviorally, listeners also more easily detected the larger deviation of 8th than 16th. When primes contained more subdivisions such as the dotted pattern, behavioral accuracy significantly decreased, indicating a Prime x Deviant interaction. These results support our hypothesis that different subdivision levels affect one’s ability to extract beats, pointing to the interplay between sequential and hierarchical processing.

Topic Area: ATTENTION: Auditory