Abstract
We used the double-rectangle cueing paradigm of Egly, Driver, and Rafal (1994) to examine the effect of cue validity on object-based and space-based attention. This paradigm has the advantage that both the spatial cueing effect (i.e., shorter RT at the cued location than at the uncued location) and the same-object effect (i.e., shorter RT for the cued object than for the uncued object), which are indicative of space-based and object-based selection respectively, can be demonstrated in the same task. However, in previous studies the cue informativeness is almost always co-varied with respect to the objects and to the locations. We dissociated the two kinds of cue informativeness by controlling the cue validity of the locations while manipulating that of the objects, or vice versa. Results from the two experiments with the object configuration in the display were compared with two control experiments in which the object configuration was removed to reveal the pure space-based attentional effect. Results showed that when the target appeared at all possible locations with equal probability, the cue validity of different parts within an object is additive. When the target appeared at the two objects with equal probability, however, response to locations with different validity was modulated by the object configuration. These results suggest that the effective cue of the same-object effect is a cue which predicts a high probability that sums the cued part and the uncued part of an object. Object configuration constrains the extent to which the location-based probability is of use.
[Supported by the National Science Council of Taiwan, NSC93-2752-H-002-008-PAE]