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Abstract:
We investigated whether velocity information is used to predict target position when hitting moving targets. Subjects hit spiders which ran from left to right at three different velocities. The spiders disappeared from view after 150, 250, or 350 ms. For each presentation time, the distance that subjects hit ahead of the disappearance point depended on spider's velocity. This means that target velocity is used. However, spiders that disappeared at different times but moved at the same speed were hit at different positions. This means that differences in target velocity are only partly accounted for.
Two models seem to be able to explain the present data reasonably well. The first assumes that velocity is not really used to predict target position, but that the position at which the target disappeared is misperceived in the direction of ocular pursuit. The second proposes that target velocity is used to predict the position at which to hit, but that such information becomes available only gradually during target presentation and therefore manifests itself only during the course of the movement.
