Western Adults' Neural Responses to an Ambiguous Rhythm: Effects of Priming With and Without Active Attention

Auditory rhythm perception involves bottom-up encoding of timing information and top-down maintenance of a particular interpretation, such as grouping beats to form meter. Top-down meter perception can be measured using electroencephalographic responses like mismatch negativity (MMN), P3a, and Steady-State Evoked Potentials (SSEPs). Previously we primed infants to perceive an ambiguous six-beat rhythm in either duple (two-beat groupings) or triple (three-beat groupings) meter by adding loudness accents to every second or third beat, respectively. For the subsequently presented unaccented rhythm, infants exhibited larger mismatch responses for pitch deviants on primed strong beats, particularly after duple priming. Here we applied the same protocol to adults while exploring the role of attention. Adults were passively primed to perceive the rhythm as duple or triple identically as the infants in the previous study (Experiment 1a), or were instructed to actively imagine the accents (Experiment 1b). Results showed that MMN and P3a were modulated by beat position and priming group, but the pattern depended on participants' music experience. Further, neural tracking (SSEPs) for the primed meter was enhanced for participants who actively imagined the accents for triple meter. Additionally, a strong bias for duple meter was evident in generally larger P3a for beat 5 compared to beat 4, regardless of priming or attention condition. As this was driven by the musically experienced participants, it likely reflects enculturation to Western music, in which duple meter dominates. These results indicate that adults' top-down meter perception is modulated by attention and enculturated biases.