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Arvin C. Arman, Geoffrey M. Boynton; Feature specificity of global-feature-based-attention. Journal of Vision 2005;5(8):159. doi: 10.1167/5.8.159.
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Purpose: Previous studies have shown evidence of a global feature-based attentional mechanism in which attention to a particular stimulus feature, such as direction of motion or color, enhances neural responses to unattended stimuli sharing that feature (Saenz, Buracas, and Boynton 2002). We used the motion aftereffect (MAE) to measure this effect psychophysically, and to determine whether this effect is specific to only the attended feature or whether it spreads to other features of the attended stimulus.
Methods: Subjects performed a two-interval-forced-choice (2IFC) speed or luminance discrimination task on a field of moving dots presented either to the left or right of fixation. The attended hemifield also contained a field of overlapping dots moving in the opposite direction. Simultaneously, on the opposing visual hemifield, a field of dots moved either in the direction of the attended dots, in the opposite direction, or had uncorrelated motion. Immediately following each 2IFC trial, subjects were presented with a unidirectional field of slowly moving dots on the previously unattended side and indicated whether the dots appeared to move either upward or downward. The strength of the MAE was measured as the speed in which the slowly moving dots appeared to move upward or downward with equal probability.
Results: We found that for both the speed and luminance discrimination task, there was a systematic influence of the direction of the attended dots on the strength of the MAE. For example, when subjects attended to either the speed or luminance of the upward moving dots on the left side, an unattended field of uncorrelated moving dots on the right side induced a MAE in the downward direction. These results suggest that attention to a stimulus enhances the response to all unattended stimuli that share any feature in common with the attended stimulus.
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