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Viola S. Störmer, George A. Alvarez; Feature-based attention elicits surround-suppression in color space. Journal of Vision 2014;14(10):21. doi: https://doi.org/10.1167/14.10.21.
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When focusing on a particular spatial location, input at the attended location is enhanced, and information at nearby locations is suppressed. While this surround suppression is well documented for spatial attention (e.g., Hopf et al., 2006), it is less clear whether similar mechanisms operate in feature-based attention. We investigated whether surround suppression exists in color space when attending to particular colors. Observers viewed overlapping sets of colorful moving dots in the left visual field (e.g., yellow among blue dots), and separate overlapping sets of dots in the right visual field (e.g., orange among blue dots). The task was to attend to two colors (e.g., yellow and orange) and to detect brief intervals of coherent motion. The colors were randomly chosen from the CIElab color space on each trial, such that target and distractor colors were on opposite sides of the color wheel. The two target colors were either the same color, or differed from each other in steps of 10° on the color wheel, up to 60° apart. We found that accuracy was highest when the target colors were identical, and decreased as the difference in color increased, reaching a minimum at 30° (identical vs. 30°, t(19)=2.4; p=0.03). Interestingly, performance gradually increased when the target colors became more distinct from each other (i.e., 30° vs. 60°; p=0.03), with performance at 60° no worse than when attending to a single color (p=.68). Thus, selecting two perceptually similar (but subtly different) colors is more difficult than selecting two perceptually distinct colors. Similar results were obtained using a visual search task. These results suggest that feature-based attention contains a narrow inhibitory surround in color space that operates across the entire visual field, supporting models of attention in which local inhibition in feature space enhances top-down selection of task-relevant objects.
Meeting abstract presented at VSS 2014
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