The action-based theories of perception, reviewed in this entry, challenge the Input-Output Picture. They maintain that perception can also depend in a noninstrumental or constitutive way on action (or, more generally, on capacities for object-directed motor control). This position has taken many different forms in the history of philosophy and psychology. Most action-based theories of perception in the last 300 years, however, have looked to action in order to explain how vision, in particular, acquires either all or some of its spatial representational content. Accordingly, these are the theories on which we shall focus here.