Abstract
The present study investigated the mechanisms responsible for the differences between visual processing for stimuli near and far from the hands. The idea that objects near the hands are immediate candidates for action led us to hypothesize that vision near the hands would be biased toward the action-oriented magnocellular (M) visual pathway that supports processing with high temporal resolution but low spatial resolution. Conversely, objects away from the hands are not immediate candidates for action and, therefore, would benefit from the perception-oriented parvocellular (P) visual pathway that supports processing with high spatial resolution but low temporal resolution. We tested this hypothesis using two important psychophysical correlates of the M and P pathways. Namely, we presented subjects with a spatial-gap detection task that involved high spatial frequency signals detectable by the P-cells, and a separate temporal-gap detection task which involved high temporal frequency signals detectable by the M-cells. Consistent with our prediction, we found better performance on the temporal-gap detection task and worse performance on the spatial-gap detection task for stimuli near the hands compared to the far stimuli. These findings suggest that altered visual processing near the hands may be caused by differential activation of the two visual pathways.
Meeting abstract presented at VSS 2012