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Fook K. Chua; Capturing attention without onset transients. Journal of Vision 2011;11(11):84. doi: 10.1167/11.11.84.
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© ARVO (1962-2015); The Authors (2016-present)
An object appearing abruptly in an unoccupied location captures attention. There are two possible explanations: (a) the transients that accompany the abrupt onset of the object cause attention to be deployed at the site of the onset; (b) as the onset represents a new entity it behooves the visual system to discover immediately aspects of the new object. Using a visual search task designed for inefficient search, we addressed the question whether onset transients are necessary for attentional capture. Observers first saw a display containing several static placeholders. A mask made up of random lines was then applied over the display. Next, the mask disappeared, revealing the search letters occupying the same locations as the placeholders. Search_set size was manipulated. To test the new object hypothesis, an additional object was inserted into the display behind the mask, making the objects's onset transients invisible. The critical comparison was between the condition where the additional object was a target, and where it was a distractor. If the new object succeeded in capturing attention, search latencies should be independent of set size if the additional object was a target. But, if onset transients are crucial, the new object, added without its onset transients visible, should fail to capture attention. The search function, therefore, would have a positive slope. But for this paradigm to constitute an effective test of the new object hypothesis, the observer must be able to establish correspondence between the pre_mask, and post_mask, objects. Only then will the new object stand out as the entity for which there was no correspondence to the pre_mask set. We show in these experiments that when conditions favored encoding of the pre-mask objects, the additional object successfully captured attention even when its onset transients were invisible. Otherwise, attentional capture by the additional object failed.
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