No Vertical Visual Field Asymmetry in Online Control: Evidence from Reaching in Depth

We sought to determine whether a putative lower-visual field (loVF) advantage for projections to the visuomotor networks of the dorsal visual pathway influences online reaching control. Participants reached to 3-dimensional depth targets presented in the loVF and upper-visual field (upVF) in binocular and monocular visual conditions, and when online vision was available (i.e., closed-loop) or unavailable (i.e., open-loop). To examine the degree to which responses were controlled online we computed the proportion of variance (R2) explained by the spatial position of the limb at distinct stages in the reaching trajectory relative to a response's ultimate movement endpoint. Results showed that binocular and closed-loop reaches exhibited shorter movement times and more online corrections (i.e., smaller R2 values) than their monocular and open-loop counterparts. Notably, however, loVF and upper-visual field reaches exhibited equivalent performance metrics across all experimental conditions. Accordingly, results provide no evidence of a loVF advantage for online reaching control to 3-dimensional targets.