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Ashleigh M. Richard, Shaun P. Vecera, Andrew Hollingworth; The role of bbject discontinuity in object-based selection. Journal of Vision 2007;7(9):1074. doi: 10.1167/7.9.1074.
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© ARVO (1962-2015); The Authors (2016-present)
The effect of objects on attentional selection has traditionally been conceived as a cost associated with either dividing or switching attention between discrete object representations. However, in a modification of the Egly et al. task, we have recently found significant effects of object perceptual structure on target discrimination across a gap in a single object. Such an effect could not be attributed to dividing or switching attention across objects, because there was only one object. In the present study, we examined whether a local object discontinuity (i.e., a gap) can account for the entire object effect in the Egly et al. paradigm. Participants were presented with circular tube-shaped stimuli. In the two-object condition, two gaps in the tube created two perceptual objects. Invalidly cued targets appeared either in the same object as the cue or in the different object. The standard same-object benefit was observed. In the one-object condition, the stimuli were identical, except there was a single gap in the tube stimulus and thus a single object. Invalidly cued targets appeared either along the continuous extent of the object or across the gap. The magnitude of the object effect (i.e., the decrement in target detection performance when the target appeared across the gap) was the same as in the two-object condition. These results suggest that local discontinuity is the primary cause of object-based effects. The data are consistent with the grouped-array theory of object-based attention, which holds that object perceptual structure constrains the spatial distribution of attention, limiting the spread of attention to continuous object regions and retarding the spread of attention across object boundaries.
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