The nature of altered vision near the hands: evidence for the magnocellular enhancement account from object correspondence through occlusion

Abstract

There is a growing body of evidence that the perception of visual stimuli is altered when they occur near the observer’s hand relative to other locations in space (see Brockmole, Davoli, Abrams, & Witt, 2013; for a review). Several accounts have been offered to explain the pattern of performance across different tasks. These have typically focused on attentional explanations (attentional prioritization and detailed attentional evaluation of stimuli in nearhand space), but more recently, it has been suggested that near-hand space enjoys enhanced magnocellular (M) input. Here we differentiate between the attentional and M-cell accounts, via a task that probes the roles of position consistency and color consistency in determining dynamic object correspondence through occlusion. We found that placing the hands near the visual display made observers use only position consistency and not color in determining object correspondence through occlusion, which is consistent with the fact that M-cells are relatively insensitive to color. In contrast, placing observers’ hands far from stimuli allowed both color and position contribute. This is evidence in favor of the M-cell enhancement account of altered vision near the hands.