Carlson Thomas A, Alvarez George A, Cavanagh Patrick
Department of Psychology, Harvard University, 33 Kirkland Street, 7th floor, Cambridge, MA 02138, USA.
Proc Natl Acad Sci U S A. 2007 Aug 14;104(33):13496-500. doi: 10.1073/pnas.0702685104. Epub 2007 Aug 2.
Our conscious experience is of a seamless visual world, but many of the cortical areas that underlie our capacity for vision have a fragmented or asymmetrical representation of visual space. In fact, the representation of the visual field is fragmented into quadrants at the level of V2, V3, and possibly V4. In theory, this division could have no functional consequences and therefore no impact on behavior. Contrary to this expectation, we find robust quadrant-level interference effects when attentively tracking two moving targets. Performance improves when target objects appear in separate quadrants (straddling either the horizontal or vertical meridian) compared with when they appear the same distance apart but within a single quadrant. These quadrant-level interference effects would not be predicted by cognitive theories of attention and tracking that do not take anatomical constraints into account. Quadrant-level interference strongly suggests that cortical areas containing a noncontiguous representation of the four quadrants of the visual field (i.e., V2, V3, and V4) impose an important constraint on attentional selection and attentive tracking.
我们的有意识体验是一个无缝的视觉世界，但构成我们视觉能力基础的许多皮层区域对视觉空间的表征却是碎片化或不对称的。事实上，在V2、V3以及可能的V4水平上，视野的表征被分割为象限。从理论上讲，这种划分可能没有功能上的影响，因此也不会对行为产生影响。与这种预期相反，我们发现当专注地跟踪两个移动目标时，会出现强烈的象限水平干扰效应。与目标物体出现在同一象限但距离相同相比，当目标物体出现在不同象限（跨越水平或垂直子午线）时，表现会有所提高。那些没有考虑解剖学限制的注意力和跟踪认知理论无法预测这些象限水平的干扰效应。象限水平干扰有力地表明，包含视野四个象限非连续表征的皮层区域（即V2、V3和V4）对注意力选择和专注跟踪施加了重要限制。
