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David Chan, Davood Gozli, Jay Pratt; Holding on to the local: Hand posture biases local processing. Journal of Vision 2014;14(10):1040. doi: 10.1167/14.10.1040.
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© ARVO (1962-2015); The Authors (2016-present)
Placing the hands near visual stimuli produces differences in visual processing compared to when the stimuli are far from the hands. One account for these differences hypotheses that hand-proximity increases the contribution of the magnocellular (M) pathway, while reducing the contribution of the parvocellular (P) pathway (e.g., Chan et. al., 2013). Since the P pathway, which predominately provides the input into the ventral visual stream, supports the grouping of perceptual elements, a strong test of the M/P account of hand proximity can be conducted by examining changes in the processing of local and global features brought about by hand posture. To accomplish this, we presented participants with Navon arrow cues (a large arrow made up of smaller arrows), whose local and global features either pointed in the same or opposite directions. After each arrow there was a variable delay followed by a peripheral target either to the left or the right of the arrow. Participants performed a localization response to these targets as quicker localization reaction times would indicate whether the local or the global information dominated visual processing. In addition, the experiment was conducted in two counterbalanced blocks; one with the participants hands on the monitor near the stimuli and the other with their hands on the keyboard far from the stimuli. We found an overall stronger local bias when the hands were near the display and a stronger overall global bias when the hands were far from the display. Moreover, global processing persisted longer (i.e., the global to local transition occurred at a longer delay) when the hands were near the stimuli. These findings support the hypothesis that near hands bias the M pathway and hands far bias the P pathway.
Meeting abstract presented at VSS 2014
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