Concomitant motor responses facilitate the acquisition of multiple timing priors beyond upper-limb contexts

The brain acquires prior distributions of target timing to improve performance in timing tasks. In everyday life, multiple events with distinct temporal statistics occur, requiring the acquisition of multiple priors. Previous work has shown that multiple-prior acquisition is facilitated when a concomitant motor response (CMR)-a nondominant hand movement or vocalization-is performed alongside a dominant-hand timing response, selectively for either of the priors. Notably, CMR effects have been observed in reaching movements, but these were specific to upper-limb contexts and absent when a foot movement was used as the CMR. Here, we show that a concomitant foot response also facilitated multiple-prior acquisition in a manual timing task. Therefore, in timing, CMR effects are not restricted to a specific motor effector combination but generalize across various effector combinations. This flexibility, coupled with the multiple motor effectors in the human body, can support adaptability to diverse temporal statistics in real-world environments.