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Charles Folk, Andrew Leber, Howard Egeth; A blip in the blink: Novel distractors produce sparing at lag 2, but not lag 1. Journal of Vision 2009;9(8):160. doi: 10.1167/9.8.160.
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© ARVO (1962-2015); The Authors (2016-present)
In the typical Attentional Blink (AB) paradigm, identification of the second of two targets in a rapidly presented visual stream is impaired at short inter-target lags, with the exception that performance is typically high when the second target appears directly after the first, a phenomenon known as lag 1 sparing. In the present studies we report a new phenomenon in which performance is selectively spared at lag 2 instead of lag 1. The paradigm is based on recent study showing that when participants are required to report the red letter in a stream of multicolored letters appearing inside a box at fixation, briefly changing the color of the box to red produces an AB (Folk, Leber, & Egeth, 2008). This effect has been attributed to the involuntary selection of the irrelevant distractor item. The present experiments varied the categorical similarity between the red target letter and the item occurring simultaneously with the red distractor box (i.e., the “distractor item”). Target letters were preceded at varying lags by a distractor item consisting of a letter, a digit, a random dot pattern, or a blank. Relative to letter distractor items, the other three distractor item types produced an enhancement in target identification that was specific to lag 2. Subsequent experiments showed that this effect is sensitive to the categorical heterogeneity of the stream items. Specifically, when the items in the stream were a mix of letters, digits, dots, or blanks, lag 1 sparing was obtained and lag 2 sparing was reduced. It is proposed that the detection of a “novel” item in an otherwise homogeneous stream results in the focusing of spatial attention that (1) requires approximately 200 ms to enact, and (2) can be dissociated from the selection of the distractor item induced by the distractor.
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