A lower visual field advantage for endpoint stability but no advantage for online movement precision.

It has been proposed that visually guided reaching movements performed in the lower visual field (LVF) of peripersonal space are more effective and efficient than their upper visual field (UVF) counterparts (Danckert and Goodale 2001). In the present investigation we sought to determine whether this purported visual field asymmetry reflects advantaged processing of online visual feedback. To accomplish that objective, participants performed discrete reaching movements to each of three target locations in the LVF and UVF. In addition, reaches were completed under conditions wherein target location remained constant throughout a reaching response (i.e., control trials) and a separate condition wherein target location unexpectedly perturbed at movement onset (i.e., experimental trials). We reasoned that the target perturbation paradigm would provide a novel means to assess a possible superior-inferior visual field asymmetry for online reaching control. In terms of the impact of a target perturbation, both visual fields demonstrated equal proficiency integrating visual feedback for online limb adjustments. Interestingly, however, the spatial distribution of movement endpoints in the LVF was less than UVF counterparts (cf. Binsted and Heath 2005). Taken together, the present findings suggest that although LVF and UVF reaches readily use visual feedback to accommodate an unexpected target perturbation, reaches in the LVF elicit advantaged spatial benefits influencing the effectiveness of online limb corrections.