アイテム詳細

要旨

Owing to the delays incurred by neural transmission and processing, there is an inevitable delay between the occurrence of an event and our ability to perceive or respond to it. Thus, if we attempt to catch (or avoid) a moving object, we must extrapolate its trajectory in order to produce an appropriate response: if we were simply to attempt to respond according to our representation of its instantaneous position, the object would have moved by the time that representation could be computed. This study concerns mechanisms by which the brain might extrapolate motion trajectories. The project examines the spatial relations among the perceived locations of moving, flashed and static stimuli. From developments of the paradigm described by Nijhawan (1994), data from three observers suggest a low-level “motion capture” mechanism which may be useful for motion extrapolation. In addition, there appears to be a temporal pooling mechanism which affects the subjective appearance of the stimulus array: although, when measured separately, the apparent locations of the flashed and moving stimuli are affected roughly equally by motion capture, there is still a striking subjective disparity between the two. Comparison of uni-directional and bi-directional stimulus arrays suggests that neither mechanism depends crucially upon eye movements.