Neural measures reveal a fixed item limit in subitizing.
Neural measures reveal a fixed item limit in subitizing.
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DOI：
10.1523/jneurosci.1218-12.2012
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发表时间：
2012-05-23
期刊：
影响因子：
--
通讯作者：
Awh E
中科院分区：
文献类型：
--
作者：
Ester EF;Drew T;Klee D;Vogel EK;Awh E
几个世纪以来，人们已经知道，人类可以快速而准确地列举出一小部分物品，这一过程被称为子化。然而，关于调节这种能力的机制仍然存在活跃的争论。例如，一些人认为，细分反映了一种固定能力的个性化机制的运作，该机制允许同时访问少数项目。然而，其他人认为，细分反映了一种连续的数字估计机制的运行，其精度随着数字的不同而变化，符合韦伯定律。关键的是，基于这两种预测的定量模型都可以对替代绩效提供合理的描述，使得仅凭受试者的行为表现来区分这些替代方案变得困难。在这里，我们试图区分固定容量和连续估计模型的亚化使用神经措施。在两个实验中，我们记录了受试者在执行要求苛刻的亚化任务时的脑电，并检查了由一系列要列举的项目引起的视觉选择的神经生理标记物(N2pc ERP成分)随集大小的变化。在这两个实验中，N2PC幅度在亚化范围内单调增加，然后在大约3个项目达到渐近极限。此外，参与者之间在这条渐近线位置上的差异对从固定容量模型得出的亚化跨度的行为估计具有很强的预测性。因此，与潜在化能力相关的神经活动表明，可以同时理解的项目的数量存在早期和离散的限制，支持这一过程的固定容量模型。
For centuries, it has been known that humans can rapidly and accurately enumerate small sets of items, a process referred to as subitizing. However, there is still active debate regarding the mechanisms that mediate this ability. For example, some have argued that subitizing reflects the operation of a fixed-capacity individuation mechanism that enables concurrent access to a small number of items. However, others have argued that subitizing reflects the operation of a continuous numerical estimation mechanism whose precision varies with numerosity in a manner consistent with Weber's law. Critically, quantitative models based on either of these predictions can provide a reasonable description of subitizing performance, making it difficult to discriminate between these alternatives solely on the basis of subjects' behavioral performance. Here, we attempted to discriminate between fixed-capacity and continuous estimation models of subitizing using neural measures. In two experiments, we recorded EEG while subjects performed a demanding subitizing task and examined set-size dependent changes in a neurophysiological marker of visual selection (the N2pc ERP component) evoked by an array of to-be-enumerated items. In both experiments, N2pc amplitudes increased monotonically within the subitizing range before reaching an asymptotic limit at around 3 items. Moreover, inter-participant differences in the location of this asymptote were strongly predictive of behavioral estimates of subitizing span derived from a fixed-capacity model. Thus, neural activity linked with subitizing ability shows evidence of an early and discrete limit in the number of items that can be concurrently apprehended, supporting a fixed-capacity model of this process.