Observer translation relative to the world creates image flow that expands from the observer's direction of translation (heading) from which the observer can recover heading direction. Yet, the image flow is often more complex, depending on rotation of the eye, scene layout and translation velocity. A number of models [1-4] have been proposed on how the human visual system extracts heading from flow in a neurophysiologic ally plausible way. These models represent heading by a set of neurons that respond to large image flow patterns and receive input from motion sensed at different im(cid:173) age locations. We analysed these models to determine the exact receptive field of these heading detectors. We find most models predict that, contrary to widespread believe, the contribut ing mo(cid:173) tion sensors have a preferred motion directed circularly rather than radially around the detector's preferred heading. Moreover, the re(cid:173) sults suggest to look for more refined structure within the circular flow, such as bi-circularity or local motion-opponency.