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Chang-Bing Huang, Ge Chen, Fang Hou, Zhong-Lin Lu; Binocular Combination: Data and Binocular Perceptual Template Model. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1512.
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© ARVO (1962-2015); The Authors (2016-present)
We have two eyes but only see one world. How visual inputs from the two eyes combine in binocular vision has been one of the major focuses in basic and clinical vision research. Here, we combined the external noise approach with dichoptic displays to develop a binocular perceptual template model (bPTM) based on the perceptual template model (PTM; Lu & Dosher, 1999, 2008) and multi-pathway contrast-gain control model (MCM; Huang et al, 2010, 2011; Hou, et al, 2013).
The method of constant stimuli was used to measure psychometric functions in a sinewave grating detection task in two spatial frequencies (1, and 4 c/deg), three external noise levels (0, 0.125, and 0.25), seven contrast levels, and four dichoptic (grating and external noise in the left/right eye only; grating in the left/right eye, external noise in the right/left eye) and one binocular conditions (grating and external noise in both eyes). There were a total of 210 conditions and 18900 trials (90 trials/condition).
We found that the threshold versus external noise contrast function (TvC) in the four dichoptic conditions were virtually identical, and were only higher than that of the binocular condition in zero and low external noise conditions. The thresholds in the highest external noise conditions were virtually identical across all five display conditions. We propose a binocular perceptual template model that consists of monocular perceptual templates, non-linear transducer, and internal noises, interocular contrast-gain control, binocular summation, binocular internal noise, and decision process. The model is compatible with the original PTM in binocular conditions, and the MCM developed for suprathreshold phase and contrast combination and stereopsis (Hou, et al, 2011). With only five parameters, the bPTM provided an excellent account of all the data (r^2 > 90%). With one additional parameter, the model can take into account of the imbalances between the two eyes in near threshold tasks, complementing the multi-pathway contrast gain control model in suprathreshold tasks.
The empirical results and bPTM shed new light on binocular combination and may provide the basis to investigate binocular vision in clinical populations.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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