Saccade amplitude influences pointing movement kinematics

THE amplitude of open-loop pointing movements to step displacements in target position is influenced by the amplitude of simultaneously produced saccadic eye movements. The time course over which this occurs was addressed in the present study. Analysis of the pointing kinematics showed that saccade amplitude had its effect only during the initial acceleration of the hand. Moreover, the magnitude of the initial acceleration was correlated with the difference in the onset times of the eye and hand movements: the closer in time the saccadic and pointing responses were initiated the larger the initial hand acceleration. Taken together, these results demonstrate that saccades influence the kinematics of simultaneously produced limb movements but only over a limited time frame.