Organisms function in particular environments, the properties of which are
reflected in the structure of their nervous systems. Therefore, sensory inf
ormation may directly specify motor behaviors. We argue that such specifica
tion involves the coupling of sensory information into appropriately struct
ured control systems that generate action. The nature of this coupling as w
ell as the structure of the control systems reflect properties of the envir
onment. This is most dramatically demonstrated when adaptive processes adju
st the underlying control system in response to changes in the environ ment
. Experimental and modeling work on posture in perturbed visual and haptic
environments is reviewed to provide evidence for these arguments. Theoretic
al modeling and autonomous robotics work that goes beyond the posture examp
le of perception-action coupling is briefly discussed, primarily to point o
ut that the integration of multiple behavioral constraints is a nontrivial
problem that has received too little attention.