Egocentric target direction, minimally specified by gaze direction and retinal location is the priamry source of information used in the visual guidance of locomtion on foot.

Perception of egocentric direction may be influenced by the structure of the visual scene, and the changing structure (retinal flow). I proposed that retinal flow is used as a source of information during the perception of position: global flow provides information about gaze movement, relative motion in the flow field can be used to anticipate future relative position. I will describe data in support of this alternative use of optic flow and outline the consequences that follow.