三数值加工系统假说:数值加工机制新探

Three number processing systems:Different features and parallel activation

数值加工的机制是数量认知领域的核心科学问题之一。三数值加工系统假说从新的角度阐释了各种数值加工机制的关系,它认为认知系统通过三种不同的机制来快速分析非符号刺激的数值:感数(subitizing)机制精确地分析1~4个刺激的数值;数量(numerosity)机制分析密度适中的刺激点阵的数量,加工误差正比于被分析的数量,符合韦伯定律;当刺激的密度超出一定范围时,密度(density)机制通过分析刺激密度来推断刺激的数量关系,加工误差正比于被加工数值的平方根。一系列研究证实,这三种数值加工机制具有不同的行为规律和脑电特征。未来研究需要探讨数量机制是否分别与感数机制、密度机制存在平行激活,从而阐明三种数值加工机制的作用关系。

Distinct mechanisms are involved in number processing of nonsymbolic stimuli.Small numbers(1~4)can be appraised rapidly and errorlessly based on the activation of subitizing system.Moderate numbers are proposed to be processed spontaneously with a constant error rate of about 20%due to the activity of numerosity system.Typically,Weber’s law for number perception is demonstrated in this number range.For large numbers,the stimulus number relationship is suggested to be inferred indirectly via density analysis,and number processing,which is fast and has an error rate proportional to the square root of the stimulus number,is mediated by density system.Different behavioral and ERP features are revealed among number tasks based on these three systems.It is proposed that parallel activation exists between subitizing and numerosity systems as well as between density and numerosity systems.Cognition relies on the system whose processing result is more precise.