Abstract
In addition to spatial locations, perceptual groups (i.e., objects) within a visual scene can guide shifts of attention (e.g., Egly et al., 1994; Vecera, 1994). One common method used to observe both space-based attention and object-based attention (OBA) effects is a spatial cuing paradigm where attention is summoned to one of two objects using a peripheral cue. Targets then appear at 1) the cue’s location (valid), 2) an uncued location on the attended object (invalid same-object), or 3) an uncued location on the unattended object (invalid different-object). OBA is illustrated by faster responses to invalid same-object trials than invalid different-object trials. One explanation for this effect is that attention spreads through the object, enhancing its representation (see Richard et al., 2008, for discussion). If attentional spreading produces the OBA effect, is it impacted by the complexity of the object? The current experiments examined the influence of an object’s structure on object-based shifts of visual attention. Observers viewed single-part objects and three-part objects in a spatial cuing paradigm. Critically, we varied the inter-stimulus interval (ISI) between the cue’s offset and the target’s onset (0, 100, 350 ms). OBA effects emerged at all ISIs for single-part objects. In comparison, an OBA effect was only observed at a 350 ms ISI for multipart objects. Because response times for invalid same-object trials decreased as ISI increased, these results suggest that attention requires time to spread through complex objects in order to observe the OBA effect in a spatial cueing paradigm. Furthermore, OBA is a mechanism that does not operate identically over all perceptual groups; rather, it is further influenced by the nature of a selected perceptual group.
Meeting abstract presented at VSS 2012