Abstract
Both eye and hand movements have been shown to draw visual attention to their goal locations during movement preparation. However, it is still a matter of debate whether a unitary attentional system underlies the selection of both eye and hand targets, or whether they are selected by independent systems. To approach this question we investigated the deployment of visual attention in coordinated eye-hand movements. In a dual movement task we asked participants to reach and look towards two different locations. The discrimination performance at the eye and hand targets was taken as a measure of the distribution of attention during motor goal selection. Our results show that attention is allocated in parallel towards both the future saccade and reach target. Importantly, the attentional benefit at the saccade target in the dual movement task was as high as in a single movement condition, in which subjects only performed an eye but no hand movement. The benefit at the reach target, however, was more pronounced in the single hand movement compared to the combined eye-hand movement condition. Thus, while attentional allocation to the saccade target was not affected by the concurrent preparation of a hand movement, the attentional benefit at the reach target suffered from the need to simultaneously prepare a saccade. Our findings indicate that action selection mechanisms for different effectors compete for attentional resources, with saccade target selection having highest priority, suggesting that targets for both eye and hand movements are represented in a unitary map of action-relevant locations.
Meeting abstract presented at VSS 2016