Visual awareness and the on-line modification of action

An influential theory of visually guided action proposes that (a) conscious perception of target displacement disrupts on-line action and (b) small ta rget perturbations are inconsequential, provided the participant is unaware of them. This study examined these claims in a study of rapid aiming movem ents to targets. Novel features included on-line verbal reports of target d isplacement, and the factorial combination of small versus large displaceme nts occurring near peak saccadic velocity or 100 ms later. Although awarene ss of target displacement had no effect on movement kinematics. even small larger displacements near peak saccadic velocity affected kinematic measure s. These results support both a strong view of visual stream separation in the on-line control of action and richer spa tial coding by unconscious pro cesses than has previously been acknowledged.