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Valerie Beck, Steven Luck; Temporal dynamics of the attentional template during visual search. Journal of Vision 2009;9(8):1185. doi: 10.1167/9.8.1185.
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© ARVO (1962-2015); The Authors (2016-present)
Extensive evidence indicates that an attentional template is used to guide attention to items that contain task-relevant features. To explore the temporal dynamics of this template, we recorded eye movements during a visual search task in which observers searched for a Landolt-C target in a 24-item array. Half of the items were red and half were blue, and we varied the probability that the target was a cued color (100%, 80%, or 50%) versus an uncued color (0%, 20%, or 50%). When the cue was 100% predictive, the first saccade was occasionally directed toward the uncued color, but almost all subsequent saccades were directed toward the cued color. The same pattern was observed when the cue was 80% predictive, except that observers switched to the uncued color if they searched most of the items of the cued color without finding the target (and then they sometimes switched back to the cued color). Thus, the template remains constant for long runs of saccades, even though this leads to long-distance saccades that skip over nearby items of the color not currently specified by the template. When the cue was non-predictive, however, observers exhibited no momentum to continue searching the same color on consecutive saccades, and they even exhibited a slight tendency to alternate between the two colors more than would be expected by chance. This is surprising from the biased competition perspective, given that the currently fixated item is presumably stored in visual working memory, which might be expected to bias subsequent saccades toward matching items. Together, these results show that the attentional template may change over the course of a single trial of visual search, and that task-irrelevant features of the currently fixated item do not have an obligatory effect on subsequent shifts of gaze.
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