This continuation application extends the investigator's research on expressive microstructure (EM). EM refers to the subtle but systematic variations in timing, dynamics, and articulation that make performed music expressive and aesthetically appealing. The present application focuses on the temporal coordination of perception and action. The basic paradigm used in many of the proposed studies is perceptual-motor synchronization. Synchronization is not only important in realistic music performance (such as ensemble playing or following a conductor's beat), but it draws on basic (neuro)psychological processes that subserve timing perception, timing in motor control, and coordination of perception and action. The first proposed series of synchronization experiments using simple auditory sequences follows up on the investigator's recent finding that error correction in synchronization occurs for timing perturbations that are perceptually subliminal (i.e., not available to consciousness). These perturbation experiments will investigate basic questions about the processes underlying the direct coupling of auditory perception with rhythmic action. A second proposed series of experiments concerns synchronization with music, played with or without expressive timing. This series includes studies that will use synchronization accuracy as a measure of temporal pattern learning and musical imagery, investigate the influence of perceived musical structure on motor timing, examine the actual coordination between two pianists playing together, and investigate the imitation of expressive timing. This research is expected to provide new insights into the largely subconscious psychological processes underlying the flexible control of timing in both musical and nonmusical contexts.