Mamassian Pascal, Jentzsch Ines, Bacon Benoit A, Schweinberger Stefan R
Department of Psychology, University of Glasgow, UK.
Neuroreport. 2003 May 23;14(7):971-5. doi: 10.1097/01.wnr.0000069061.85441.f2.
Psychophysical studies have shown that human observers resolve shape-from-shading ambiguities by assuming that light is coming from above-left. Using event-related potentials (ERPs), we measured the processing time of the perception of an ambiguous shaded pattern. We found that the N2 component followed the change of perceived shape with stimulus orientation. We also found that the P1 component in occipital and temporal areas was correlated with the observers' idiosyncratic bias for light source position. The precocity of the correlated ERP components suggests that the light source is represented early in the visual system. Altogether, our results indicate that shape-from-shading is a mostly bottom-up mechanism.
心理物理学研究表明，人类观察者通过假设光线来自左上方来解决由阴影产生的形状歧义。我们使用事件相关电位（ERP）测量了对模糊阴影图案感知的处理时间。我们发现N2成分随刺激方向跟随感知形状的变化。我们还发现枕叶和颞叶区域的P1成分与观察者对光源位置的个体偏好相关。相关ERP成分的早熟表明光源在视觉系统中早期就被表征。总之，我们的结果表明，由阴影产生形状是一种主要的自下而上的机制。
