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Barbara Montagna, Yaffa Yeshurun, Marisa Carrasco; Differential effects of endogenous and exogenous covert attention on texture segmentation. Journal of Vision 2007;7(9):912. doi: 10.1167/7.9.912.
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© ARVO (1962-2015); The Authors (2016-present)
Goal: Transient attention, considered to be automatic, improves or impairs performance in a texture segmentation task constrained by spatial resolution (Yeshurun & Carrasco, 1998). Would endogenous (sustained) attention, considered to be voluntary, also impair performance? While keeping stimuli and task constant, we compared the effects of these two types of attention in this texture segmentation task. In this task, performance peaks at mid-peripheral locations, where spatial resolution is optimal for the texture scale, and decreases towards the periphery and center, where spatial resolution is either too low or too high. Transient attention improves performance in the periphery, where spatial resolution is too low, but actually impairs performance at central locations, where spatial resolution is already too high (Yeshurun & Carrasco, 1998). This counterintuitive central attentional impairment indicates that transient attention increases spatial resolution even when it is detrimental to performance, and suggests that it does so by default. If sustained attention is a more flexible mechanism, can it either increase or decrease spatial resolution depending on task demands?
Methods: In a 2-IFC task, observers indicated which of two texture displays contained a target varying in eccentricity. Observers were assigned to either the endogenous or the exogenous attention condition. To manipulate transient attention, peripheral precues appeared adjacent to the target location; to manipulate sustained attention, symbolic precues indicated to the observers where to voluntarily allocate their attention. Attentional effects were evaluated against a neutral cue.
Results: Transient attention impaired performance at central locations (replicating Yeshurun and Carrasco, 1998). In contrast, sustained attention benefited performance at all eccentricities. These results are consistent with the possibility that sustained attention increased spatial resolution where it was too low (periphery), and decreased resolution where it was too high (central locations), and suggest that sustained attention is flexible and adjusts to task demands to optimize performance.
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