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Sharon L. Sally, Zoltan Vidnyanszky, Thomas Papathomas; Feature-based attention: Effects of eccentricity. Journal of Vision 2007;7(9):991. doi: 10.1167/7.9.991.
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© ARVO (1962-2015); The Authors (2016-present)
PURPOSE: Feature-based attention modulates visual processing such that attending to a particular attribute or feature increases the sensitivity to that feature throughout the visual field. The goal of the present study was to examine the magnitude of feature-based attention as a function of eccentricity in a dual-task orientation discrimination procedure.
METHOD: Stimuli were high-contrast Gabor patterns of different sizes presented at 2.5°, 5°, 10° and 15° on both sides of fixation in the horizontal plane. All Gabors were magnified versions of each other. The stimulus size presented at each eccentricity was selected to equate single-task orientation discrimination performance for a small Gabor target at the closest eccentricity. The dual-task procedure consisted of a primary orientation discrimination task that remained constant (e.g., thresholds for vertical stimuli in the primary aperture) while interleaved horizontal and vertical orientation thresholds were measured for the secondary task in the other aperture. Single-task performance was measured using stimuli identical to the dual task.
RESULTS: Single task horizontal and vertical orientation thresholds were similar. In all cases, orientation thresholds increased markedly in the dual task paradigm, particularly for the secondary task. On average, thresholds increased by a factor of 1.46 for the primary task and by a factor of 2 for the secondary task. Performance was not as severely degraded on the secondary task when the primary and secondary tasks involved the same orientation. This indicates an effect of feature-based attention on thresholds. We found proportionately smaller threshold elevations for the secondary task with increasing eccentricity in the same-orientation condition.
CONCLUSION: The effects of feature-based attention on orientation discrimination become more pronounced with retinal eccentricity. This might be explained by inhibitory attentional mechanisms that lead to spatial suppression surrounding the focus of attention
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