Spatial non-homogeneity of the antagonistic surround in motion perception.



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Serrano Pedraza, Ignacio and Hogg, Ellen L and Read, Jenny C A (2011) Spatial non-homogeneity of the antagonistic surround in motion perception. Journal of vision, 11 (2). ISSN 1534-7362

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At high contrast, duration thresholds for motion direction discrimination deteriorate with increasing stimulus size. This counterintuitive result has been explained by the center-surround antagonism present in the neurons of visual area MT. Conversely, at very low contrast, direction discrimination improves with increasing size, a result that has been explained by spatial summation. In this investigation, we study the effects of stimulus shape and contrast on center-surround antagonism. Using adaptive Bayesian staircases, we measured duration thresholds of 5 subjects for vertically oriented Gabor patches of 1 cycle/deg with two types of oval Gaussian windows, one vertically elongated (Sx = 0.35, Sy = 2.5 deg) and other horizontally elongated (Sx = 2.5, Sy = 0.35 deg) moving rightward or leftward at a speed of 2 deg/s. We found that at high contrast (92%) duration thresholds were lower for vertically than horizontally elongated windows. However, at low contrast (2.8%), we found that duration thresholds were lower for horizontally than vertically elongated windows. These asymmetric results mirror the spatial non-homogeneity of the antagonistic surround found in MT neurons and suggest that the underlying center-surround antagonism is stronger along the direction of motion.

Item Type:Article
Uncontrolled Keywords:Motion perception, Center–surround antagonism, Surround suppression, Spatial summation, MT neurons
Subjects:Medical sciences > Psychology > Experimental psychology
Medical sciences > Psychology > Perception
Medical sciences > Optics > Visual perception
ID Code:36286
Deposited On:11 Apr 2016 16:08
Last Modified:20 Apr 2016 14:31

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