Submovements

Submovements are discrete, small components that compose a larger voluntary movement. They are commonly observed during reaching, pointing, and tracking tasks and may appear as a sequence of velocity bursts or corrective adjustments nested within a single intended action. The concept captures the idea that motor output is not always a smooth, continuous flow but can be assembled from multiple smaller movement events.

Submovements are typically detected in high-resolution kinematic data by identifying local maxima in speed, abrupt changes in direction, or changes in acceleration or jerk. Researchers may model a trajectory as a succession of short movement segments separated by brief pauses or dwell times. The occurrence, timing, and magnitude of submovements can depend on task characteristics such as speed-accuracy demands, target size, perturbations, or feedback availability.

Interpretations of submovements often frame them as evidence for intermittent control in motor systems, in which the brain updates motor commands in discrete steps rather than in a perfectly smooth manner. They may reflect corrective responses driven by sensory feedback (visual or proprioceptive) or by internal predictions, as well as contributions from noise and biomechanical constraints. Practice, instruction, or easier targets can reduce their number or refine their size, suggesting adaptive changes in control strategy.

Submovements have been studied across domains including hand movements, cursor-based tasks, eye movements, and speech. They provide a useful lens for understanding endpoint accuracy, correction latency, and how motor plans are generated, refined, and executed in real time.