Galfano Giovanni, Penolazzi Barbara, Vervaeck Ineke, Angrilli Alessandro, Umiltà Carlo
Department of Developmental and Social Psychology, University of Padua, Italy.
Cortex. 2009 Nov-Dec;45(10):1167-77. doi: 10.1016/j.cortex.2008.09.003. Epub 2008 Oct 1.
The present study was designed to ascertain whether the cortical dynamics underlying multiplication fact retrieval can be modulated as a function of arithmetic relatedness. To this end, event-related brain potentials (ERPs) were recorded from 22 participants engaged in a number-matching task. The task was to decide whether a single probe number had been shown as part of a previously presented pair of cue numbers. Probes in the non-matching condition (50% of total trials) were either the product of the cue numbers (strong cue-probe association), the multiple of either cue numbers (weak cue-probe association), or an arithmetically neutral number with respect to the cue numbers (no cue-probe association). Behavioral data showed a clear interference effect (LeFevre interference), in that performance in the non-matching condition was significantly better when the probe number was arithmetically neutral compared to when it was arithmetically related to the cue digits either strongly (i.e., through the product) or weakly (i.e., through its neighbor in the multiplication table). LeFevre interference was not statistically different in magnitude for the two arithmetically related conditions. In contrast, ERPs allowed us to dissociate cortical processing dynamics for these latter conditions: whereas initially (250-350 ms) both product and neighbor probes evoked a relatively more pronounced positivity compared to neutral probes, in a later interval (350-450 ms, N400-like component), neighbors critically diverged from products, showing relatively more negative values, similar to those of neutral probes. The observed dissociation in ERP measures is interpreted as evidence of activation spreading in the network of multiplication facts, with the short-lasting response elicited by neighbors likely reflecting activation dissipating over time because of a weaker association to the cue digits.
本研究旨在确定乘法运算事实检索背后的皮层动力学是否可以根据算术相关性进行调节。为此，对22名参与数字匹配任务的参与者记录了事件相关脑电位（ERP）。该任务是判断单个探测数字是否作为先前呈现的一对提示数字的一部分出现。非匹配条件下的探测数字（占总试验次数的50%）要么是提示数字的乘积（强提示-探测关联）、其中一个提示数字的倍数（弱提示-探测关联），要么是与提示数字在算术上无关的数字（无提示-探测关联）。行为数据显示出明显的干扰效应（勒菲弗干扰），即当探测数字在算术上无关时，非匹配条件下的表现明显优于当它与提示数字在算术上有强关联（即通过乘积）或弱关联（即通过乘法表中的相邻数字）时。两种算术相关条件下的勒菲弗干扰在幅度上没有统计学差异。相比之下，ERP使我们能够区分后两种条件下的皮层处理动力学：最初（250 - 350毫秒），乘积和相邻数字探测均比中性探测诱发相对更明显的正波，而在随后的时间段（350 - 450毫秒，类N400成分），相邻数字与乘积显著不同，显示出相对更负的值，类似于中性探测。ERP测量中观察到的这种分离被解释为乘法运算事实网络中激活扩散的证据，相邻数字引发的短暂反应可能反映了由于与提示数字的关联较弱，激活随时间消散。
