Independent selection of eye and hand targets suggests effector-specific attentional mechanisms

Both eye and hand movements bind visual attention to their target locations during movement preparation. However, it remains contentious whether eye and hand targets are selected jointly by a single selection system, or individually by independent systems. To unravel the controversy, we investigated the deployment of visual attention - a proxy of motor target selection - in coordinated eye-hand movements. Results show that attention builds up in parallel both at the eye and the hand target. Importantly, the allocation of attention to one effector's motor target was not affected by the concurrent preparation of the other effector's movement at any time during movement preparation. This demonstrates that eye and hand targets are represented in separate, effector-specific maps of action-relevant locations. The eye-hand synchronisation that is frequently observed on the behavioral level must emerge from mutual influences of the two effector systems at later, post-attentional processing stages.