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Raymond Ee, Casper J. Erkelens; Conscious selection of bi-stable 3D percepts described by neural population codes. Journal of Vision 2002;2(7):459. doi: 10.1167/2.7.459.
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© ARVO (1962-2015); The Authors (2016-present)
Understanding conscious visual perception is one of the main challenges in vision science. Here we developed both an experimental paradigm and a model to study conscious selection of bi-stable percepts in stereoscopic vision. The paradigm exploits a visual stimulus in which we independently manipulated two signals that our brain uses to retrieve the 3D layout of a scene. One of the signals is binocular disparity (i.e. according to the geometry of vision with two frontal eyes), the other is monocular perspective. The stimulus consisted of a slanted planar grid. When the slants specified by disparity and perspective had the same polarity subjects perceived one single grid, the perceived slant being a reconciliation of disparity-specified and perspective-specified slant. But when disparity- and perspective-specified slants had opposite polarities subjects perceived either a disparity-dominated or a perspective-dominated 3D representation of the slanted grid. A novel feature of the paradigm is that our observers were able to attentively select one of the two alternative percepts at will in a well-controlled way. Our paradigm provides, therefore, not only a promising tool to study conscious vision psychophysically but also to study it physiologically through either neurophysiology or fMRI. The experimental data were well described by a neural-population-code model in which perceived slant is determined by the combined activity of three neural populations (representing disparity, perspective and residual slant signals, respectively).
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