Casco Clara, Grieco Alba, Campana Gianluca, Corvino Maria Pia, Caputo Giovanni
Dipartimento di Psicologia Generale, Università degli Studi di Padova, Via Venezia 8, 35131 Padua, Italy.
Vision Res. 2005 Aug;45(18):2384-96. doi: 10.1016/j.visres.2005.02.022. Epub 2005 Apr 8.
To investigate whether processing underlying texture segmentation is limited when texture is not attended, we measured orientation discrimination accuracy and visual evoked potentials (VEPs) while a texture bar was cyclically alternated with a uniform texture, either attended or not. Orientation discrimination was maximum when the bar was explicitly attended, above threshold when implicitly attended, and fell to just chance when unattended, suggesting that orientation discrimination based on grouping of elements along texture boundary requires explicit attention. We analyzed tsVEPs (variations in VEP amplitude obtained by algebraic subtraction of uniform-texture from segmented-texture VEPs) elicited by the texture boundary orientation discrimination task. When texture was unattended, tsVEPs still reflected local texture segregation. We found larger amplitudes of early tsVEP components (N75, P100, N150, N200) when texture boundary was parallel to texture elements, indicating a saliency effect, perhaps at V1 level. This effect was modulated by attention, disappearing when the texture was not attended, a result indicating that attention facilitates grouping by collinearity in the direction of the texture boundary.
为了研究当纹理未被关注时，潜在的纹理分割处理是否受到限制，我们在一个纹理条与均匀纹理周期性交替出现的情况下，测量了方向辨别准确率和视觉诱发电位（VEP），纹理条出现时要么被明确关注，要么未被关注。当纹理条被明确关注时，方向辨别准确率最高，当被隐性关注时高于阈值，而当未被关注时则降至随机水平，这表明基于沿着纹理边界的元素分组的方向辨别需要明确的注意力。我们分析了由纹理边界方向辨别任务引发的tsVEP（通过从分割纹理VEP中减去均匀纹理VEP经代数运算得到的VEP幅度变化）。当纹理未被关注时，tsVEP仍然反映了局部纹理分离。当纹理边界与纹理元素平行时，我们发现早期tsVEP成分（N75、P100、N150、N200）的幅度更大，这表明可能在V1水平存在显著效应。这种效应受到注意力的调制，当纹理未被关注时消失，这一结果表明注意力促进了在纹理边界方向上通过共线性进行的分组。
