Task-relevant and Task-irrelevant Dimensions Are Modulated Independently at a Task-irrelevant Location

Abstract

Single-cell and fMRI experiments indicate that task-relevant features are enhanced globally across the visual field (VF). Moreover, this global feature-based attention can spread to task-irrelevant features of the attended object. Here we ask whether a task-irrelevant feature, by virtue of being bound to a task-relevant feature, can also be enhanced at a task-irrelevant location. Specifically, we asked whether attending to the color of moving dots in one VF would influence the motion signal to colored moving dots in the other VF. Participants attended to either red or cyan dots, superimposed and moving in opposite directions. Critically, the color and motion of dots present in the opposite VF varied as a function of the attended dots such that they were either the same color/same direction, same color/opposite direction, opposite color/same direction, or opposite color/opposite direction as the attended dots. We found greater activity in ventral visual cortex when either the color or direction of motion matched the color or direction of motion at the attended location. Similar effects were found for direction of motion in human medial temporal/medial superior temporal cortex. Moreover, the color and motion effects did not interact in any region. Together, these results suggest that the coselection of an object's features modulates those features independently beyond the selected object.