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Shira Tkacz-Domb, Yaffa Yeshurun; The minimal size of the attentional window is larger when measured via the pupillary light response. Journal of Vision 2018;18(10):1189. doi: https://doi.org/10.1167/18.10.1189.
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The goal of this study was to measure the minimal size of the attentional window (i.e., its size when attention is narrowly focused) using attentional modulation of the pupillary light response (PLR) – pupillary constriction when covertly attending a brighter area relative to attending a darker area. This allowed us to avoid confounds and biases involved in relying on observers' response (e.g., RT). Specifically, we presented a continuously rotating T to the right and left of fixation at an eccentricity of 7°. Four task-irrelevant disks surrounded each T with varying inter-stimuli distances (Experiment 1: 1°, 4°, 7° or 11°; Experiment 2: 1°, 2°, 3° or 4°). The disks were bright on one side and dark on the other. Prior to the onset of the Ts and disks, a central cue instructed observers which T to attend. The task was to indicate the number of times the attended T assumed an upright orientation. Overall luminance levels were identical across trials. In both experiments, pupil size was modulated by the disks' luminance only when they were positioned 1° away from the T. That is, with this inter-stimuli distance pupil size was significantly smaller when the disks surrounding the attended T were bright than when they were dark. With larger distances pupil size was not affected by the luminance of the disks at the attended side. Hence, it seems that at a distance of 1° from the target the task-irrelevant disks were nevertheless attended, suggesting that the radius of the attentional window is at least 1°, but less than 2°. These findings reveal that the minimal size of the attentional window is twice as large as that established when relying on RT. Currently, we use PLR to examine whether the size of the attentional window scales with eccentricity.
Meeting abstract presented at VSS 2018
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