Heading judgement from second-order motion

We examined human heading judgement from second-order motion which was gene rated by random-dots with the contrast polarity determined randomly on each frame. It was found that human observers can judge heading fairly accurate ly from second-order motion when pure translation is simulated or when self -motion toward a ground plane with gaze rotation is simulated but they cann ot when self-motion toward cloud-like random dots with gaze rotations is si mulated. It is suggested that the human visual system cannot decompose the flow fields into rotational and translational components by using second-or der motion information alone, but it can do in some ways from the flow fiel d of the ground plane. (C) 2000 Elsevier Science Ltd. All rights reserved.