The Visual N1 Is Sensitive to Deviations from Natural Texture Appearance

Disruptions of natural texture appearance are known to negatively impact performance in texture discrimination tasks, for example, such that contrast-negated textures, synthetic textures, and textures depicting abstract art are processed less efficiently than natural textures. Presently, we examined how visual ERP responses (the P1 and the N1 in particular) were affected by violations of natural texture appearance. We presented participants with images depicting either natural textures or synthetic textures made from the original stimuli. Both stimulus types were additionally rendered either in positive or negative contrast. These appearance manipulations (negation and texture synthesis) preserve a range of low-level features, but also disrupt higher-order aspects of texture appearance. We recorded continuous EEG while participants completed a same/different image discrimination task using these images and measured both the P1 and N1 components over occipital recording sites. While the P1 exhibited no sensitivity to either contrast polarity or real/synthetic appearance, the N1 was sensitive to both deviations from natural appearance. Polarity reversal and synthetic appearance affected the N1 latency differently, however, suggesting a differential impact on processing. Our results suggest that stages of visual processing indexed by the P1 and N1 are sensitive to high-order statistical regularities in natural textures and also suggest that distinct violations of natural appearance impact neural responses differently.

学界已知，自然纹理外观的破坏会对纹理判别任务的作业绩效产生负面影响，例如对比度反转纹理、合成纹理以及抽象艺术纹理的加工效率，均低于自然纹理。本研究旨在探究自然纹理外观的违背会如何影响视觉事件相关电位（Event-Related Potential, ERP）反应，尤其关注P1与N1两种成分。我们向被试呈现两类图像：一类为自然纹理图像，另一类为基于原始刺激生成的合成纹理图像。两类刺激均被进一步处理为正对比度与负对比度两种呈现形式。此类外观操控手段（对比度反转与纹理合成）虽保留了一系列低层次视觉特征，却同时破坏了纹理外观的高阶属性。我们在被试完成基于上述图像的异同判别任务时，同步记录了连续脑电图（Electroencephalogram, EEG），并在枕叶记录位点采集了P1与N1成分。尽管P1成分对对比度极性或自然/合成外观均无敏感性，但N1成分对这两类偏离自然外观的变化均表现出敏感性。然而，对比度极性反转与合成外观对N1潜伏期的影响存在差异，这提示二者对视觉加工的作用机制有所不同。本研究结果表明，由P1与N1成分所表征的视觉加工阶段，对自然纹理中的高阶统计规律具有敏感性；同时也证实，不同类型的自然外观违背会对神经反应产生差异化影响。