Johnson Aaron P, Prins Nicolaas, Kingdom Frederick A A, Baker Curtis L
Department of Psychology, Concordia University, 7141 Sherbrooke Street West, Room SP-245.05 Montréal, Que., Canada H4B 1R6.
Vision Res. 2007 Aug;47(17):2281-90. doi: 10.1016/j.visres.2007.05.003. Epub 2007 Jul 5.
Natural scenes contain localized variations in both first-order (luminance) and second-order (contrast and texture) information. There is much evidence that first- and second-order stimuli are detected by distinct mechanisms in the mammalian visual system. However, in natural scenes the two kinds of information tend to be spatially correlated. Do correlated and uncorrelated combinations of first- and second-order stimuli differentially affect perception? To address this question we employed orientation-modulated textures in which observers were required to discriminate the spatial frequency of the texture modulation. The textures consisted of micropatterns defined as either local variations in luminance (first-order) or luminance contrast (second-order). Performance was robust with textures composed of only first-order micropatterns, but impossible with only second-order micropatterns. However, when the second-order micropatterns were combined with the first-order micropatterns, they enhanced performance when the two were spatially correlated, but impaired performance when the two were spatially uncorrelated. We conclude that local second-order information may enhance texture modulation discrimination provided it is combined with first-order information in an ecologically valid manner.
自然场景在一阶（亮度）和二阶（对比度和纹理）信息中都包含局部变化。有许多证据表明，一阶和二阶刺激是由哺乳动物视觉系统中的不同机制检测到的。然而，在自然场景中，这两种信息往往在空间上是相关的。一阶和二阶刺激的相关和不相关组合对感知的影响是否不同？为了解决这个问题，我们采用了方向调制纹理，要求观察者辨别纹理调制的空间频率。这些纹理由微图案组成，微图案被定义为亮度的局部变化（一阶）或亮度对比度的局部变化（二阶）。仅由一阶微图案组成的纹理，观察者的表现很稳健，但仅由二阶微图案组成的纹理，观察者则无法辨别。然而，当二阶微图案与一阶微图案组合时，二者空间相关时会提高表现，而二者空间不相关时则会损害表现。我们得出结论，局部二阶信息如果以生态有效的方式与一阶信息相结合，可能会增强纹理调制辨别能力。
