The critical physiological mechanism that grounds the sensory input to make it an experience is “corollary discharge”: a reference copy of a motor command sent to a comparator circuit from the action-initiating brain areas. This comparator mechanism allows the brain to examine the relationship between a true change in the sensory input and a change due to self-initiated movement of the sensors. The same corollary discharge mechanism also serves active sensing, the process by which sensory receptors can be most efficiently utilized to sense the environment.
