Neural correlates of emotion-label vs. emotion-laden word processing in late bilinguals: evidence from an ERP study

The brain processes underlying the distinction between emotion-label words (e.g. happy, sad) and emotion-laden words (e.g. successful, failed) remain inconclusive in bilingualism research. The present study aims to directly compare the processing of these two types of emotion words in both the first language (L1) and second language (L2) by recording event-related potentials (ERP) from late Chinese-English bilinguals during a lexical decision task. The results revealed that in the early word processing stages, the N170 emotion effect emerged only for L1 negative emotion-laden words and L2 negative emotion-label words. In addition, larger early posterior negativity (EPN) was elicited by emotion-laden words than emotion-label words in both L1 and L2. In the later processing stages, the N400 emotion effect was evident for L1 emotion words, excluding positive emotion-laden words, while it was absent in L2. Notably, L1 emotion words elicited enhanced N400 and attenuated late positive complex (LPC) compared to those in L2. Taken together, these findings confirmed the engagement of emotion, and highlighted the modulation of emotion word type and valence on word processing in both early and late processing stages. Different neural mechanisms between L1 and L2 in processing written emotion words were elucidated.

双语研究中，情绪标注词（如happy、sad）与情绪负载词（如successful、failed）背后的大脑加工机制尚无定论。本研究通过在词汇判断任务中记录汉英晚期双语者的事件相关电位（event-related potentials, ERP），旨在直接比较第一语言（L1）与第二语言（L2）内两类情绪词的加工过程。结果显示，在词汇加工的早期阶段，N170情绪效应仅在L1负性情绪负载词与L2负性情绪标注词中出现。此外，在L1与L2中，情绪负载词诱发的早期后部负波（early posterior negativity, EPN）均大于情绪标注词。在加工的后期阶段，L1情绪词（排除正性情绪负载词）呈现出显著的N400情绪效应，而该效应在L2中并未观测到。值得注意的是，相较于L2中的情绪词，L1情绪词诱发了更强的N400电位与更弱的晚期正成分（late positive complex, LPC）。综上，本研究结果证实了情绪加工的参与性，并强调了情绪词类型与效价对词汇加工早期及晚期阶段的调控作用。本研究阐明了母语与第二语言在书面情绪词加工中存在的差异化神经机制。