Abstract
Saccades are rapid, goal-directed, eye movements that typically last less than 140 ms. Due to the short duration of saccades, it is generally believed that they are entirely ballistic (pre-planned) and that information obtained throughout a saccade cannot be used to modify the trajectory of that saccade (e.g., Becker, 1991). Several recent findings, however, have called the ballistic nature of saccades into question. In one study, Gaveau et al. (2003) found that displacing visual targets during saccadic suppression can cause changes in saccadic endpoint. To investigate if feedback-based control contributed to the adjusted saccadic endpoints on these displaced target trials, we conducted detailed kinematic analyses of saccadic eye movements on trials without target displacement (reference trials), trials with target displacement (jump trials), and memory-based trials. Consistent with previous work, we found that the saccadic end-point was displaced in the direction of the target on jump trials. Although the kinematic analyses revealed several differences between the manner in which saccades on reference and memory trials were planned and executed, the analyses did not reveal any differences between the kinematics of saccades on jump and reference trials. Overall, these results support the hypothesis that saccades can be corrected online, but there was no evidence that there is an additional degree of online correction in jump trials relative to reference trials.Acknowledgments: This research was supported by funding from the Natural Sciences and Engineering Research Council of Canada, the Ontario Ministry of Research and Innovation, and the Naitonal Science Foundation.