Evidence for flow-parsing in radial flow displays.

Retinal motion of objects is not in itself enough to signal whether or how objects are moving in the world; the same pattern of retinal motion can result from movement of the object, the observer or both. Estimation of scene-relative movement of an object is vital for successful completion of many simple everyday tasks. Recent research has provided evidence for a neural flow-parsing mechanism which uses the brain's sensitivity to optic flow to separate retinal motion signals into those components due to observer movement and those due to the movement of objects in the scene. In this study we provide further evidence that flow-parsing is implicated in the assessment of object trajectory during observer movement. Furthermore, it is shown that flow-parsing involves a global analysis of retinal motion, as might be expected if optic flow processing underpinned this mechanism.