Perceived object shape affects the perceived direction of self-movement.

The 'direct-perception' model of heading perception posits that heading is computed directly from optic flow without an intervening structural representation of environmental layout. Here, I give an example in which such a representation is seen to play a role in the interpretation of optic flow. Manipulating the outline of concave objects to give an erroneous percept of convexity caused the perceived direction of heading during a stimulated approach to change as well. Thus, the representation of environmental structure provides the context for using and interpreting image motion.