Bex Peter J, Dakin Steven C, Simmers Anita J
Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK.
Vision Res. 2003 Dec;43(27):2895-904. doi: 10.1016/s0042-6989(03)00460-7.
Our ability to identify alphanumeric characters can be impaired by the presence of nearby features, especially when the target is presented in the peripheral visual field, a phenomenon is known as crowding. We measured the effects of motion on acuity and on the spatial extent of crowding. In line with many previous studies, acuity decreased and crowding increased with eccentricity. Acuity also decreased for moving targets, but the absolute size of crowding zones remained relatively invariant of speed at each eccentricity. The two-dimensional shape of crowding zones was measured with a single flanking element on each side of the target. Crowding zones were elongated radially about central vision, relative to tangential zones, and were also asymmetrical: a more peripheral flanking element crowded more effectively than a more foveal one; and a flanking element that moved ahead of the target crowded more effectively than one that trailed behind it. These results reveal asymmetrical space-time dependent regions of visual integration that are radially organised about central vision.
我们识别字母数字字符的能力可能会因附近特征的存在而受损，尤其是当目标出现在周边视野时，这种现象被称为拥挤效应。我们测量了运动对视力和拥挤效应空间范围的影响。与之前的许多研究一致，视力随着离心率的增加而下降，拥挤效应也随之增加。运动目标的视力也会下降，但在每个离心率下，拥挤区域的绝对大小相对速度保持不变。用目标两侧各一个侧翼元素测量拥挤区域的二维形状。相对于切向区域，拥挤区域围绕中央视觉呈放射状拉长，并且也是不对称的：更周边的侧翼元素比更靠近中央凹的元素拥挤效应更明显；在目标之前移动的侧翼元素比在目标之后移动的元素拥挤效应更明显。这些结果揭示了围绕中央视觉呈放射状组织的不对称时空依赖的视觉整合区域。
