Competition between salience and informational value for saccade adaptation

Abstract

What we see is influenced by where we look. When confronted with multiple relevant targets, inaccurate saccade target selection can impair perceptual performance. Here we ask whether endpoint selection can be optimized by the mechanism maintaining saccade accuracy: saccade adaptation. Therefore, we introduce a double-target adaptation task, where a presaccadic peripheral stimulus (plaid) splits vertically into its two components (Gabor patches) during horizontal saccades. While both targets were task-relevant, one of them provided more information for the perceptual task, because it could only be identified after the saccade with near-foveal vision. The other target was highly salient and could also be identified in the presaccadic plaid using peripheral vision. This double-target paradigm induced saccade adaptation: Without a perceptual task, participants adapted to the salient target. When both targets were judged sequentially, participants mostly adapted to the target they had to judge first. When targets were judged simultaneously, endpoints were biased toward the informative target but showed no gradual learning and fell short of optimality. We observed gradual adaptation when targets shifted randomly such that a strategic adjustment of endpoints was not possible. Overall, these findings show that when multiple targets compete, our oculomotor system can learn to adjust endpoints in order to maximize information for perception. Yet individual variability and other factors affecting target priority play a crucial role.