Ivanov Iliya V, Kramer Daniel J, Mullen Kathy T
McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Quebec H3A 1A1, Canada.
McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Quebec H3A 1A1, Canada.
Vision Res. 2014 Jan;94:41-50. doi: 10.1016/j.visres.2013.10.019. Epub 2013 Nov 9.
Slant is the degree to which a surface recedes or slopes away from the observer about the horizontal axis. The perception of surface slant may be derived from static monocular cues, including linear perspective and foreshortening, applied to single shapes or to multi-element textures. It is still unclear the extent to which color vision can use these cues to determine slant in the absence of achromatic contrast. Although previous demonstrations have shown that some pictures and images may lose their depth when presented at isoluminance, this has not been tested systematically using stimuli within the spatio-temporal passband of color vision. Here we test whether the foreshortening cue from surface compression (change in the ratio of width to length) can induce slant perception for single shapes for both color and luminance vision. We use radial frequency patterns with narrowband spatio-temporal properties. In the first experiment, both a manual task (lever rotation) and a visual task (line rotation) are used as metrics to measure the perception of slant for achromatic, red-green isoluminant and S-cone isolating stimuli. In the second experiment, we measure slant discrimination thresholds as a function of depicted slant in a 2AFC paradigm and find similar thresholds for chromatic and achromatic stimuli. We conclude that both color and luminance vision can use the foreshortening of a single surface to perceive slant, with performances similar to those obtained using other strong cues for slant, such as texture. This has implications for the role of color in monocular 3D vision, and the cortical organization used in 3D object perception.
倾斜度是指一个表面围绕水平轴相对于观察者后退或倾斜的程度。表面倾斜度的感知可能源自静态单眼线索，包括应用于单个形状或多元素纹理的线性透视和缩短。在没有消色差对比度的情况下，色觉能在多大程度上利用这些线索来确定倾斜度仍不清楚。尽管先前的演示表明，一些图片和图像在等亮度条件下呈现时可能会失去深度，但尚未使用色觉的时空通带内的刺激进行系统测试。在这里，我们测试来自表面压缩（宽度与长度之比的变化）的缩短线索是否能诱导色觉和亮度视觉对单个形状的倾斜感知。我们使用具有窄带时空特性的径向频率图案。在第一个实验中，手动任务（杠杆旋转）和视觉任务（线条旋转）都被用作衡量消色差、红绿色等亮度和S锥体隔离刺激的倾斜感知的指标。在第二个实验中，我们在2AFC范式中测量倾斜辨别阈值作为所描绘倾斜度的函数，并发现彩色和消色差刺激的阈值相似。我们得出结论，色觉和亮度视觉都可以利用单个表面的缩短来感知倾斜度，其表现与使用其他强烈的倾斜线索（如纹理）所获得的表现相似。这对颜色在单眼3D视觉中的作用以及3D物体感知中使用的皮质组织具有启示意义。
