Stanford University, Stanford, USA.
Harvard Medical School, Boston, USA.
Sci Rep. 2021 Feb 26;11(1):4777. doi: 10.1038/s41598-021-82782-4.
Recent studies have reported evidence that listeners' brains process meaning differently in speech with an in-group as compared to an out-group accent. However, among studies that have used electroencephalography (EEG) to examine neural correlates of semantic processing of speech in different accents, the details of findings are often in conflict, potentially reflecting critical variations in experimental design and/or data analysis parameters. To determine which of these factors might be driving inconsistencies in results across studies, we systematically investigate how analysis parameter sets from several of these studies impact results obtained from our own EEG data set. Data were collected from forty-nine monolingual North American English listeners in an event-related potential (ERP) paradigm as they listened to semantically congruent and incongruent sentences spoken in an American accent and an Indian accent. Several key effects of in-group as compared to out-group accent were robust across the range of parameters found in the literature, including more negative scalp-wide responses to incongruence in the N400 range, more positive posterior responses to congruence in the N400 range, and more positive posterior responses to incongruence in the P600 range. These findings, however, are not fully consistent with the reported observations of the studies whose parameters we used, indicating variation in experimental design may be at play. Other reported effects only emerged under a subset of the analytical parameters tested, suggesting that analytical parameters also drive differences. We hope this spurs discussion of analytical parameters and investigation of the contributions of individual study design variables in this growing field.
最近的研究报告表明，与外群体口音相比，听众的大脑在处理带有内群体口音的言语时会以不同的方式处理意义。然而，在使用脑电图 (EEG) 研究不同口音言语语义处理的神经相关性的研究中，研究结果往往存在冲突，这可能反映了实验设计和/或数据分析参数的关键差异。为了确定哪些因素可能导致研究结果不一致，我们系统地研究了这些研究中的几个分析参数集如何影响我们自己的 EEG 数据集的结果。研究数据来自 49 名母语为北美英语的单语者，他们在事件相关电位 (ERP) 范式中聆听以美国口音和印度口音说出的语义一致和不一致的句子。与外群体口音相比，内群体口音的几个关键影响在文献中发现的参数范围内具有稳健性，包括在 N400 范围内对不一致的头皮广泛反应更负，在 N400 范围内对一致的后反应更正，以及在 P600 范围内对不一致的后反应更正。然而，这些发现与我们使用的参数的研究报告的观察结果并不完全一致，表明实验设计的变化可能起作用。其他报告的影响仅在测试的分析参数子集下出现，这表明分析参数也会导致差异。我们希望这能激发对分析参数的讨论，并在这个不断发展的领域中研究个别研究设计变量的贡献。
