Physical action, also called motor behavior, is the output side of the input/output system of the brain. Sensation/perception is our input and action is our output. Our physical behavior ranges from simple reflexive movements up to intentional, planned, and complex movements.

Voluntary movements are those movements that are potentially under conscious control. Examples include walking, standing up, raising our arm, getting dressed, shaking our head, etc. Involuntary movements are those movements that are not under conscious control or that generally happen automatically without conscious thought. Examples include breathing, heartbeat, posture, and motor coordination.