Contributions of parvocellular and magnocellular pathways to visual perception near the hands are not fixed, but can be dynamically altered.

Abstract

Visual perception is altered near the hands, and several mechanisms have been proposed to account for this, including differences in attention and a bias toward magnocellular-preferential processing. Here we directly pitted these theories against one another in a visual search task consisting of either magnocellular- or parvocellular-preferred stimuli. Surprisingly, we found that when a large number of items are in the display, there is a parvocellular processing bias in near-hand space. Considered in the context of existing results, this indicates that hand proximity does not entail an inflexible bias toward magnocellular processing, but instead that the attentional demands of the task can dynamically alter the balance between magnocellular and parvocellular processing that accompanies hand proximity.