Visually guided locomotion: psychophysical evidence for a neural mechanism sensitive to flow patterns.

Inspecting a radial flow pattern depressed visual sensitivity to changes in the size of a small test square, but only when the square was located near the focus of the flow pattern. The result suggests that precise visual judgments of one's direction of forward motion with respect to the outside world may be mediated by an already known neural organization sensitive to changes in the size of small objects.