School of Psychology, University of Birmingham, Birmingham B15 2TT, United Kingdom.
Proc Natl Acad Sci U S A. 2010 Sep 14;107(37):16309-14. doi: 10.1073/pnas.1006285107. Epub 2010 Aug 30.
In perceiving 3D shape from ambiguous shading patterns, humans use the prior knowledge that the light is located above their head and slightly to the left. Although this observation has fascinated scientists and artists for a long time, the neural basis of this "light from above left" preference for the interpretation of 3D shape remains largely unexplored. Combining behavioral and functional MRI measurements coupled with multivoxel pattern analysis, we show that activations in early visual areas predict best the light source direction irrespective of the perceived shape, but activations in higher occipitotemporal and parietal areas predict better the perceived 3D shape irrespective of the light direction. These findings demonstrate that illumination is processed earlier than the representation of 3D shape in the visual system. In contrast to previous suggestions, we propose that prior knowledge about illumination is processed in a bottom-up manner and influences the interpretation of 3D structure at higher stages of processing.
从模棱两可的阴影模式中感知 3D 形状时，人类会利用光位于头顶上方且略微偏左的先验知识。尽管这一观察结果长期以来一直令科学家和艺术家着迷，但对于这种“来自上方左侧的光”偏好用于解释 3D 形状的神经基础，仍在很大程度上尚未得到探索。我们结合行为和功能磁共振测量以及多体素模式分析，表明早期视觉区域的激活可以最佳地预测光源方向，而与感知到的形状无关，但在更高的枕颞和顶叶区域的激活可以更好地预测感知到的 3D 形状，而与光的方向无关。这些发现表明，在视觉系统中，光照的处理比 3D 形状的表示更早。与之前的建议相反，我们提出关于光照的先验知识是通过自下而上的方式处理的，并在处理的较高阶段影响 3D 结构的解释。
