Abstract
We examined whether the two visual systems (“what” and “how”; Milner & Goodale, 1995) share common object representations by using the double-rectangle cueing paradigm of Egly, Driver, and Rafal (1994). The reliance of the action/perception system on external object presentation was examined, especially the tolerance of disruption of the presentation of objects in view. One of the two oblong objects (a shaver and a remote controller) was cued, followed by a red ant (the target) shown on one end of the two objects. In the action task, participants were asked to lift their finger from the spacebar to grasp the red ant on the screen as soon as possible once they saw it. Reaction times for finger lifting and grasping were measured. In the perception task, participants were asked to press the spacebar as soon as when they detected the ant. Three critical manipulations about the objects were that they were either continuously present in view, disappeared after being cued then reappeared at the target display, or disappeared throughout the trial after being cued. Results indicate robust same-object effects (i.e., shorter reaction times for targets appeared on the cued object compared to the uncued object) for continuously presented objects, and no such effect is observed when the objects disappear from view after being cued. However, the same-object effect observed in the disappear-then-reappear condition occurs only for the perception task but not for the action task. The action system thus seems to rely on continuous object presentation whereas the perception system can tolerate the disruption of object presentation, as long as the object appears with the target. These results suggest different object representations for action and perception during the attentional cueing task used.
Supported by the National Science Council of Taiwan, NSC95-2752-H-002-007-PAE and 95-2413-H-002-020