Rhythmic perception and performance: A California sea lion spontaneously entrains body movements to match beat sequences with gradually changing tempos

Are nonhumans capable of spontaneously synchronizing to novel and dynamic rhythms? Humans can quickly perceive and adapt motor movements to match beat sequences of varying complexities—a trait previously considered neurologically specialized. Current literature on the neurological processes that support human rhythm perception organize rhythmic difficulty into tiers, and few other species have met these foundational checkpoints. The most accomplished animal subject in this conversation is Ronan, a California sea lion (Zalophus californianus) who has achieved the early milestones of successful entrainment and synchronization to isochronous (evenly timed) sounds. An exploratory probe of Ronan’s entrainment response to a non-isochronous stimulus was conducted using a popular song with a steadily accelerating tempo. Her immediate synchronized performance encouraged further exploration of her ability to perceive and entrain to dynamic stimuli. We then systematically exposed Ronan to metronomic tracks that gradually increase or decrease at set rates of 25%, 50%, 75%, and 100% change. Ronan spontaneously tempo-matched all stimuli, both accelerating and decelerating, revealing potential neurological support for complex rhythm perception. This work continues to demonstrate how conditioned learning paradigms can uncover previously unknown aspects of cognitive auditory processing and provides opportunities to further explore this unique blend of rhythm perception and production.