Are subitizing and counting implemented as separate or functionally overlapping processes?
Are subitizing and counting implemented as separate or functionally overlapping processes?
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DOI：
10.1006/nimg.2001.0980
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发表时间：
2002-02-01
期刊：
影响因子：
5.7
通讯作者：
Price, CJ
中科院分区：
文献类型：
--
作者：
Piazza, M;Mechelli, A;Price, CJ
以四个或更少的对象为一小组的枚举是非常快速和准确的(通常称为“子化”)，但对于四个以上的项(“计数”)，会变得更慢且更容易出错。人们提出了许多理论来解释这种二分法，其中大多数理论认为，“下位化”和“计数”是两个本质上不同的、可分离的过程。相比之下，其他人则提出，这两种操作反映了复杂程度上的两个不同层面。在这篇文章中，我们提出了一项PET研究，试图在神经水平上表征潜在化和计数，以调查它们是作为独立的还是功能重叠的过程来实现的。受试者对数字(1-4和6-9个点)和空间排列(规范的和随机的)不同的点的视觉排列进行计数。结果显示了一个包括纹外区、枕中区和顶内区的共同的亚片化和计数网络。这个网络的强度和空间范围受点数及其空间排列的调节：激活随着视觉阵列中项目数的增加而增加，当计数6-9个随机排列的项目时，激活达到最大峰值和范围。亚底化和计数之间的直接比较表明，相对于亚底化，计数与这一枕顶网络中活动的增加相关，而亚底化并没有显示出相对于计数的激活增加的区域。结果与在可分离的神经系统中实施这两个过程的想法背道而驰。(C)2002年爱思唯尔科学公司。
Enumeration of small groups of four or fewer objects is very fast and accurate (often called "subitizing"), but gets slower and more error prone for more than four items ("counting"). Many theories have been proposed to account for this dichotomy, most suggesting that "subitizing" and "counting" are two qualitatively different and separable processes. Others, in contrast, have proposed that the two operations reflect two different levels along a continuum of complexity. In this paper we present a PET study that attempts to characterize subitizing and counting at a neural level in order to investigate whether they are implemented as separate or functionally overlapping processes. Subjects performed an enumeration task on visual arrays of dots that varied in numerosity (1-4 and 6-9 dots) and spatial arrangement (canonical and random). The results demonstrated a common network for subitizing and counting that comprises extrastriate middle occipital and intraparietal areas. The intensity and spatial extent of this network were modulated by the number of dots and their spatial arrangement: activation increased as the number of items in the visual array increased, reaching maximum peak and extent for counting 6-9 randomly arranged items. Direct comparison between subitizing and counting showed that counting, relative to subitizing, was correlated with increased activity in this occipitoparietal network, while subitizing did not show areas of increased activation with respect to counting. Results speak against the idea of the two processes being implemented in separable neural systems. (C) 2002 Elsevier Science.