Abstract
Natural tasks, such as catching a fly, require a continuous readout of sensory information to decide whether, when, and where to act. These goal-directed actions are preceded by perceptual decisions relying on brain areas also involved in the planning and execution of eye movements. Recent studies showed that eye movements during or shortly after decision formation are modulated by decision outcome. For example, saccades are initiated earlier and faster in the decision-congruent direction in motion discrimination tasks. However, whether eye movements contribute to decision formation is not yet known. We tested observers in EyeStrike—a rapid manual interception task—allowing us to evaluate eye movements during go/no-go decisions. Observers (n=45) viewed a briefly presented (100–300 ms) moving target that followed a linear-diagonal trajectory either passing (“go” response required) or missing (“no-go” required) a strike box. Observers indicated their choice by intercepting the target inside the strike box (go) or by withholding a hand movement (no-go). The target elicited a combination of smooth pursuit and saccadic eye movements. The first saccade was reliably initiated ~240 ms after target onset. Hand movements were initiated shortly after the initial saccade onset (~180 ms), indicating that decision formation occurred prior to the initial saccade. Importantly, more accurate early pursuit was related to higher decision accuracy, reflected in a negative correlation between eye velocity error (between target onset and initial saccade) and decision accuracy. These results suggest that pursuit eye movements continuously update decision processes until the initiation of the first saccade.
Acknowledgement: Natural Sciences and Engineering Research Council Discovery Grant and Accelerator Supplement to MS