Object-based allocation of visual attention in response to exogenous, but not endogenous, spatial precues

Two rectangular objects were presented in the visual field, and subjects' attention was directed to a location on one rectangle by either an endogenous or an exogenous spatial precue. Similar experiments by Egly, Driver, and Rafal (1994) have shown an object-based effect: slower target identification when the target was presented on the uncued abject, even when the spatial proximity of the target's and the cue's location was controlled. The experiment reported here showed that this object-based effect occurs only for exogenous cues, Considered in the light of other literature on spatial cuing, it seems that attention is influenced by nearby objects when exogenously directed to a location, but it is independent of such objects when endogenously directed to a location.