Ooi Teng Leng, He Zijiang J
Department of Basic Sciences, Pennsylvania College of Optometry, 8360 Old York Road, Elkins Park, PA 19027, USA.
Perception. 2006;35(5):581-603. doi: 10.1068/p5489.
Theoretical and empirical studies show that the visual system relies on boundary contours and surface features (e.g. textures) to represent 3-D surfaces. When the surface to be represented has little texture information, or has a periodic texture pattern (grating), the boundary contour information assumes a larger weight in representing the surface. Adopting the premise that the mechanisms of 3-D surface representation also determine binocular rivalry perception, the current paper focuses on whether boundary contours have a similar role in binocular rivalry. In experiment 1, we tested the prediction that the visual system prefers selecting an image/figure defined by boundary contours for rivalry dominance. We designed a binocular rivalry stimulus wherein one half-image has a boundary contour defined by a grating disk on a background with an orthogonal grating orientation. The other half-image consists solely of the (same orientation) grating background without the grating disk, ie no boundary contour. Confirming our prediction, the predominance for the half-image with the grating disk is approximately 90%, despite the fact that the grating disk corresponds to an area with orthogonal grating in the fellow eye. The advantage of the grating disk is dramatically reduced to about 50% predominance when a boundary contour is added to the background-only half-image at the location corresponding to the grating disk. We attribute this reduced advantage to the formation of a corresponding binocular boundary contour. In experiment 2 the grating background was substituted by a random-dot background in a similar stimulus design. We found that the perceptual salience of the corresponding binocular boundary contours extracted by the interocular matching process is an important factor in determining the dynamics of binocular rivalry. Experiment 3 showed that vertical lines with uneven thickness and spacing as the background reduce the contribution of the monocular boundary contour of the grating disk in binocular rivalry, possibly through the formation of binocular boundary contours between the local edges (vertical components) of the vertical lines and the corresponding grating disk.
理论和实证研究表明，视觉系统依靠边界轮廓和表面特征（如纹理）来表征三维表面。当要表征的表面几乎没有纹理信息，或者具有周期性纹理图案（光栅）时，边界轮廓信息在表征表面时权重更大。基于三维表面表征机制也决定双眼竞争感知这一前提，本文聚焦于边界轮廓在双眼竞争中是否具有类似作用。在实验1中，我们测试了视觉系统在竞争优势方面更倾向于选择由边界轮廓定义的图像/图形这一预测。我们设计了一种双眼竞争刺激，其中一个半图像有一个由背景上的光栅盘定义的边界轮廓，背景具有正交的光栅方向。另一个半图像仅由（相同方向）的光栅背景组成，没有光栅盘，即没有边界轮廓。证实了我们的预测，带有光栅盘的半图像的优势度约为90%，尽管光栅盘对应于另一只眼睛中具有正交光栅的区域。当在仅背景的半图像中与光栅盘对应的位置添加一个边界轮廓时，光栅盘的优势急剧降低至约50%的优势度。我们将这种优势降低归因于相应双眼边界轮廓的形成。在实验2中，在类似的刺激设计中，光栅背景被随机点背景所取代。我们发现，通过双眼匹配过程提取的相应双眼边界轮廓的感知显著性是决定双眼竞争动态的一个重要因素。实验3表明，以厚度和间距不均匀的垂直线为背景会降低光栅盘的单眼边界轮廓在双眼竞争中的作用，这可能是通过在垂直线的局部边缘（垂直分量）与相应的光栅盘之间形成双眼边界轮廓实现的。
