Neural evidence linking visual object enumeration and attention
Neural evidence linking visual object enumeration and attention
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DOI：
10.1162/089892999563238
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发表时间：
1999-01-01
影响因子：
3.2
通讯作者：
Grafton, ST
中科院分区：
文献类型：
--
作者：
Sathian, K;Simon, TJ;Grafton, ST
对于四个或更少的项，视觉对象枚举是快速和准确的，但对于四个以上的项，视觉对象枚举速度慢且容易出错。这种二分法最近被认为与视觉注意现象有关，因为研究结果表明，对少量物体的“潜在化”是预先注意的，而对四个以上的物体进行“计数”则需要注意的空间转移。我们在神经层面对这种联系进行了评估，使用(H2O)-O-15正电子发射断层扫描来测量局部脑血流的变化，同时受试者列举了在由水平和垂直条组成的16条视觉显示中“弹出”的目标垂直条的数量。相对于单一靶点的情况，亚化(一到四个靶点)激活枕骨纹外皮质的焦点，这与早期注意前视觉过程的参与是一致的。相对于亚硝酸化，计数(五到八个目标)激活了一个广泛的脑区网络，包括与转移视觉注意力有关的多个焦点--两侧顶上皮质的大片区域和右侧额叶下部皮质的一个焦点。这些结果为将亚化-计数二分法映射到可分离的过程提供了第一个直接的神经支持，这些过程调节前注意视觉和视觉注意的转移。
Visual object enumeration is rapid and accurate for four or fewer items but slow and error-prone for over four items. This dichotomy has recently been linked to visual attentional phenomena by findings suggesting that "subitizing" of small sets of objects is preattentive whereas "counting" of over four items demands spatial shifts of attention. We evaluated this link at a neural level, using (H2O)-O-15 positron emission tomography to measure changes in regional cerebral blood flow while subjects enumerated the number of target vertical bars that "popped out" of a 16-bar visual display consisting of both horizontal and vertical bars. Relative to a condition with a single target, subitizing (one to four targets) activated foci in the occipital extrastriate cortex, consistent with involvement of early, preattentive visual processes. Relative to subitizing, counting (five to eight targets) activated a widespread network of brain regions, including multiple foci implicated in shifting visual attention-large regions of the superior parietal cortex bilaterally and a focus in the right inferior frontal cortex. These results offer the first direct neural support for mapping the subitizing-counting dichotomy onto separable processes mediating preattentive vision and shifts of visual attention.