Department of Psychology University of Pittsburgh Pittsburgh PA USA.
Learning Research and Development Center University of Pittsburgh Pittsburgh PA USA.
Brain Behav. 2018 Mar 8;8(4):e00938. doi: 10.1002/brb3.938. eCollection 2018 Apr.
Adults can represent numerical information in nonsymbolic and symbolic formats and flexibly switch between the two. While some studies suggest a strong link between the two number representation systems (e.g., Piazza, Izard, Pinel, Le Bihan, & Dehaene, 2004 , 44(3), 547), other studies show evidence against the strong-link hypothesis (e.g., Lyons, Ansari, & Beilock, 2012 , 141(4), 635). This inconsistency could arise from the relation between task demands and the closeness of the link between the two number systems.
We used a passive viewing task and event-related potentials (ERP) to examine the temporal dynamics of the implicit integration between the nonsymbolic and symbolic systems. We focused on two ERP components over posterior scalp sites that were found to be sensitive to numerical distances and ratio differences in both numerical formats: a negative component that peaks around 170 ms poststimulus (N1) and a positive component that peaks around 200 ms poststimulus (P2p). We examined adults' (=55) ERPs when they were passively viewing simultaneously presented dot quantities and Arabic numerals (i.e., nonsymbolic and symbolic numerical information) in the double-digit range. For each stimulus, the nonsymbolic and symbolic content either matched or mismatched in number. We also asked each participant to estimate dot quantities in a separate behavioral task and observed that they tended to underestimate the actual dot quantities, suggesting a need to adjust the match between nonsymbolic and symbolic information to reflect the perceived quantity of the nonsymbolic information.
Using this adjustment, participants showed greater N1 and P2p amplitudes when perceived dot quantities matched Arabic numerals than when there was a mismatch. However, no differences were found between the unadjusted match and mismatch conditions.
Our findings suggest that adults rapidly integrate nonsymbolic and symbolic formats of double-digit numbers, but evidence of such integration is best observed when the perceived (rather than veridical) dot quantity is considered.
成年人可以用非符号和符号两种形式来表示数字信息，并在两者之间灵活切换。虽然一些研究表明两种数字表示系统之间存在很强的联系（例如，Piazza 等人，2004 年，44（3），547），但其他研究表明证据与强联系假设相矛盾（例如，Lyons 等人，2012 年，141（4），635）。这种不一致可能是由于任务需求与两种数字系统之间的联系紧密程度之间的关系。
我们使用被动观看任务和事件相关电位（ERP）来检查非符号和符号系统之间隐含整合的时间动态。我们专注于头皮后部两个对数值距离和两种数值格式的比值差异敏感的 ERP 成分：刺激后约 170 毫秒出现的负成分（N1）和刺激后约 200 毫秒出现的正成分（P2p）。我们检查了 55 名成年人在被动观看同时呈现的点数量和阿拉伯数字（即非符号和符号数字信息）时的 ERP。对于每个刺激，非符号和符号内容在数量上匹配或不匹配。我们还要求每个参与者在单独的行为任务中估计点数量，并观察到他们倾向于低估实际点数量，这表明需要调整非符号和符号信息之间的匹配，以反映非符号信息的感知数量。
使用这种调整，当感知点数量与阿拉伯数字匹配时，参与者的 N1 和 P2p 振幅较大，而当存在不匹配时则较小。然而，在未调整的匹配和不匹配条件之间没有发现差异。
我们的研究结果表明，成年人可以快速整合两位数的非符号和符号格式，但当考虑到感知（而不是真实）的点数量时，这种整合的证据最好观察到。
