Abstract
It has been previously demonstrated that attention can be allocated to regions of space or perceptual objects. Although they are not mutually exclusive, the exact relationship between the two modes of selection is not fully understood yet. Egly, Driver, and Rafal (1994) first showed both components within one paradigm, but cuing a location inside an object confounded the space/object reference frames. The present study dissociated space and object using two variants of the Egly paradigm. Experiments 1 and 2 were Go/No-Go tasks in which the spatial and object validity was either high or low (80% vs. 20%) and the target appeared at a cued or uncued location inside a cued or uncued object (CLCO, ULCO, CLUO, ULUO). The two objects formed a cross-like display with one occluding the other in Experiment 1, and a ring-like display with two banana-like shapes in Experiment 2. In particular, the design of these stimulus configurations enabled a new condition (CLUO) in which a part of one object could occupy the same spatial location as a previously cued object. We found both space- and object-based effects within these paradigms when object validity was high. More importantly, spatial and object validity interacted – the object-based effect was smaller when the spatial location was cued. In contrast, when attention was allocated to a specific location under high spatial validity, only a space-based component of visual attention was observed. With spatial cuing, a location-based representation appeared to suffice and attention did not spread readily through the whole object. Together, the results are suggestive of selection at different levels of processing and raise questions about the role of perceptual surfaces in object-based attention.
Meeting abstract presented at VSS 2012