Visual pre-selection of future hand paths in obstacle avoidance

In three experiments we studied the role of visual attention during the preparation of manual movements around an obstacle by analyzing event-related potentials. Participants performed rapid hand movements to a goal position avoiding a central obstacle either to the right or to the left, depending on the pitch of the acoustical go-signal. We used a dot probe paradigm in order to map the deployment of visual attention in the field during the motor preparation. Briefly after the go-signal but still before the hand movement started a visual transient was flashed either on the planned pathway of the hand to the left or right of the obstacle (congruent trials) or on the opposite, movement-irrelevant side (incongruent trials). The P1/N1-components that were induced by the onset of the dot probe were enhanced in congruent trials in which the visual transient was presented on the planned path of the hand. The results indicate that during movement preparation attention is not only allocated to the obstacle itself but also to the planned trajectory the hand is going to take around the obstacle. In Experiment 2 and 3 we quantitatively compared the amount of attention that is deployed to the object’s margin with the attentional selection of the future reach path.