Cross-orientation masking in human color vision: application of a two-stage model to assess dichoptic and monocular sources of suppression.
J Vis
; 13(6): 15, 2013 May 28.
Article
em En
| MEDLINE
| ID: mdl-23716122
ABSTRACT
Cross-orientation masking (XOM) occurs when the detection of a test grating is masked by a superimposed grating at an orthogonal orientation, and is thought to reveal the suppressive effects mediating contrast normalization. Medina and Mullen (2009) reported that XOM was greater for chromatic than achromatic stimuli at equivalent spatial and temporal frequencies. Here we address whether the greater suppression found in binocular color vision originates from a monocular or interocular site, or both. We measure monocular and dichoptic masking functions for red-green color contrast and achromatic contrast at three different spatial frequencies (0.375, 0.75, and 1.5 cpd, 2 Hz). We fit these functions with a modified two-stage masking model (Meese & Baker, 2009) to extract the monocular and interocular weights of suppression. We find that the weight of monocular suppression is significantly higher for color than achromatic contrast, whereas dichoptic suppression is similar for both. These effects are invariant across spatial frequency. We then apply the model to the binocular masking data using the measured values of the monocular and interocular sources of suppression and show that these are sufficient to account for color binocular masking. We conclude that the greater strength of chromatic XOM has a monocular origin that transfers through to the binocular site.
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Base de dados:
MEDLINE
Assunto principal:
Mascaramento Perceptivo
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Visão Binocular
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Visão Monocular
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Visão de Cores
Limite:
Humans
Idioma:
En
Ano de publicação:
2013
Tipo de documento:
Article