Person:
Serrano Pedraza, Ignacio

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First Name
Ignacio
Last Name
Serrano Pedraza
URI
https://hdl.handle.net/20.500.14352/80226
Affiliation
Universidad Complutense de Madrid
Faculty / Institute
Psicología
Department
Psicología Experimental, Procesos Cognitivos y Logopedia
Area
Psicología Básica
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Author: Hogg, Ellen L × Subject: 535 ×

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