Representational Development of Direction in Motion Perception: A Fragile Process

Response to a change in direction is more rapid if the target moves in a predictable direction before the change than if the pre-change direction is not predictable. However, if the target trajectory is viewed for approximately half a second before the change in direction, the effect of directional predictability disappears. Visual information gathered prior to change in direction is used to construct an increasingly more accurate representation of target trajectory. To study this process, we inject various temporal transients into the trajectory prior to the change in direction. We find that extraction of directional information is interrupted if: (i) motion continues along a constant trajectory, but the target disappears briefly behind an implicit or real occluder, (ii) the target pauses briefly, but remains visible, or (iii) the target changes speed briefly, while continuing to move in the same direction. The theoretical implications for motion perception are discussed. These implications include a framework for understanding interactions between stimulus-derived information and a priori information.