Abstract
Directing attention to a peripheral location increases the firing rate of neurons with receptive fields at that location, effectively boosting the gain of objects appearing within the attended region of space (space-based attention, SA). In addition, directing attention to a visual feature (direction of motion, color, etc.) increases the firing rate of all neurons tuned to the attended feature, independent of the neuron's spatial receptive field (feature-based attention, FBA). While both SA and FBA have been studied extensively in isolation, little work has focused on understanding how SA and FBA combine to support efficient visual processing. In the present study, subjects performed a two-interval forced choice task in which they were cued to attend to a peripheral location, to a direction of motion, or to both. Each interval contained four random-dot apertures (200ms exposure, 200ms gap); one of the apertures contained correlated motion during either the first or the second temporal interval (one of four possible directions). Accuracy was higher overall when the cue was valid compared to when the cue was invalid (when the cue indicated incorrect location and/or direction motion). Moreover, cueing effects were largest when both the target location and the target feature were cued, slightly smaller when only the target location was cued, and smallest when only the feature was cued. The results support models in which the effects of SA and FBA combine to jointly influence the representation of attended stimuli in the visual field.
Supported by RO1EY2925 (GMB) and T32-MH20002 (JS)