title: Binocular combination of stimulus orientation.
abstract: When two sine waves that differ slightly in orientation are presented to the two eyes separately, a single cyclopean sine wave is perceived. However, it is unclear how the brain calculates its orientation. Here, we used a signal detection rating method to estimate the perceived orientation when the two eyes were presented with Gabor patches that differed in both orientation and contrast. We found a nearly linear combination of orientation when both targets had the same contrast. However, the binocular percept shifted away from the linear prediction towards the orientation with the higher contrast, depending on both the base contrast and the contrast ratio. We found that stimuli that differ slightly in orientation are combined into a single percept, similarly for monocular and binocular presentation, with a bias that depends on the interocular contrast ratio. Our results are well fitted by gain-control models, and are consistent with a previous study that favoured the DSKL model that successfully predicts binocular phase and contrast combination and binocular contrast discrimination. In this model, the departures from linearity may be explained on the basis of mutual suppression and mutual enhancement, both of which are stronger under dichoptic than monocular conditions.
authors.affiliation: School of Optometry and Helen Wills Neuroscience Institute , UC Berkeley , Berkeley, CA 94720 , USA.
authors.forename: O
authors.initials: O
authors.lastname: Yehezkel
authors.affiliation: School of Optometry and Helen Wills Neuroscience Institute , UC Berkeley , Berkeley, CA 94720 , USA.
authors.forename: J
authors.initials: J
authors.lastname: Ding
authors.affiliation: Goldschleger Eye Research Institute, Sackler Faculty of Medicine , Tel Aviv University, Sheba Medical Center , Tel Hashomer 52621 , Israel.
authors.forename: A
authors.initials: A
authors.lastname: Sterkin
authors.affiliation: Faculty of Life Sciences, Optometry and Vision Sciences , Bar-Ilan University , Ramat-Gan , Israel.
authors.forename: U
authors.initials: U
authors.lastname: Polat
authors.affiliation: School of Optometry and Helen Wills Neuroscience Institute , UC Berkeley , Berkeley, CA 94720 , USA.
authors.forename: D M
authors.identifier: 0000-0002-5350-8639
authors.initials: DM
authors.lastname: Levi
keywords: DSKL model; binocular combination; contrast; interocular enhancement; interocular suppression; orientation