Object and space-based attentional selection in three-dimensional space

It has been previously demonstrated that visual attention has an extent in depth (3D space) as well as an extent in the fronto-parallel plane (2D space). Numerous experiments have also demonstrated that attention can be allocated to objects, and that object-based attention can overcome some of the costs associated with moving attention about in 2D space. In real visual environments, objects often have an extent in depth. Four experiments were conducted to examine the nature of object-based attention in 3D space. The experiments demonstrated large object-based attention benefits, as well as costs for switching attention in depth. However, the costs associated with switching attention in depth were eliminated with objects that had an extent in depth. Experiments 2-4 examined the interaction of spatial attention in 3D space and object-based attention. Evidence was found for the spread of spatial attention to objects. However, contrary to other work (Lavie & Driver, 1996), neither non-predictive exogenous spatial cues (Experiment 2) nor predictive exogenous spatial cues (Experiments 3 and 4) were able to eliminate object-based attention, suggesting that object-based attention can remain intact despite the allocation of attention spatially.