information in locomotor control was explored. First, the recovery of heading from RF was examined when ER information was manipulated; results confirmed that ER signals affect heading judgments. Then the task was translated to steering curved paths and the availability and veracity of VD was manipulated with either degraded or systematically biased RF. Large steering errors resulted from selective manipulation of RF and VD, providing strong evidence for the combination of RF, ER, and VD. The relative weighting applied to RF and VD was estimated. A point-attractor model is proposed that combines redundant sources of information for robust locomotor control with flexible trajectory planning through active gaze. We routinely locomote through the world and reach our goals successfully despite course changes and variable eye or body positions. This requires a highly efficient system for processing visual information to pick a path, maintain a course, and arrive at our desired destination. Solutions to these problems have centered on the

Fajen & Warren 5) has been useful in drawing out what is and isn’t known about the roles of optic flow and perceived egocentric direction in the visual guidance of locomotion. The proposal that perceived egocentric direction has a central role in the guidance of locomotion 6 appears to no longer be disputed. Here we wish to clarify some implications of the strong version of this proposal, that locomotion relies exclusively on perceived egocentric direction. How does an observer perceive the egocentric direction of an object? The direction relative to the trunk is minimally given by the orientation of the head on the trunk, the orientation of the eye in the head and the retinal location of the target (note that, lest there be any confusion, current direction of locomotion is not required). However, there are other influences on perception of egocentric direction. The structure within the optic array, or retinal image, can affect perception of egocentric direction 7,8. Furthermore, and of special interest, changes within the optic array (‘optic flow’) can also influence perception of direction. Natural optic flow experienced when walking has been shown to change perceived egocentric direction 9. Artificially generated translational flow has also been shown to have a fast-acting influence on perceived direction 10,11. A simple interpretation of these effects is that in the former case optic flow recalibrates perceived egocentric direction, whereas in the