University of Konstanz, Konstanz, DE, Germany.
Radboud University, Nijmegen, NL, the Netherlands.
Cortex. 2022 Jun;151:70-88. doi: 10.1016/j.cortex.2022.02.011. Epub 2022 Mar 16.
Successful spoken-word recognition relies on interplay between lexical and sublexical processing. Previous research demonstrated that listeners readily shift between more lexically-biased and more sublexically-biased modes of processing in response to the situational context in which language comprehension takes place. Recognizing words in the presence of background noise reduces the perceptual evidence for the speech signal and - compared to the clear - results in greater uncertainty. It has been proposed that, when dealing with greater uncertainty, listeners rely more strongly on sublexical processing. The present study tested this proposal using behavioral and electroencephalography (EEG) measures. We reasoned that such an adjustment would be reflected in changes in the effects of variables predicting recognition performance with loci at lexical and sublexical levels, respectively. We presented native speakers of Dutch with words featuring substantial variability in (1) word frequency (locus at lexical level), (2) phonological neighborhood density (loci at lexical and sublexical levels) and (3) phonotactic probability (locus at sublexical level). Each participant heard each word in noise (presented at one of three signal-to-noise ratios) and in the clear and performed a two-stage lexical decision and transcription task while EEG was recorded. Using linear mixed-effects analyses, we observed behavioral evidence that listeners relied more strongly on sublexical processing when speech quality decreased. Mixed-effects modelling of the EEG signal in the clear condition showed that sublexical effects were reflected in early modulations of ERP components (e.g., within the first 300 msec post word onset). In noise, EEG effects occurred later and involved multiple regions activated in parallel. Taken together, we found evidence - especially in the behavioral data - supporting previous accounts that the presence of background noise induces a stronger reliance on sublexical processing.
成功的口语识别依赖于词汇和次词汇处理的相互作用。先前的研究表明，听众可以根据语言理解所处的情境，轻松地在更偏向词汇的处理模式和更偏向次词汇的处理模式之间转换。在存在背景噪声的情况下识别单词会减少语音信号的感知证据，并且与清晰的语音相比，结果会产生更大的不确定性。有人提出，在处理更大的不确定性时，听众会更依赖于次词汇处理。本研究使用行为和脑电图 (EEG) 测量来检验这一假设。我们推断，这种调整将反映在分别预测词汇和次词汇水平上识别性能的变量的影响变化中。我们向荷兰语母语者展示了具有以下特征的单词：（1）词频（词汇水平），（2）音位邻域密度（词汇和次词汇水平）和（3）语音规则概率（次词汇水平）。每个参与者都在噪声中听到每个单词（在三个信噪比之一中呈现）和清晰的单词，并在记录 EEG 时执行了两个阶段的词汇判断和转录任务。使用线性混合效应分析，我们观察到行为证据表明，当语音质量下降时，听众更依赖于次词汇处理。在清晰条件下对 EEG 信号进行的混合效应建模表明，次词汇效应反映在 ERP 成分的早期调制中（例如，在单词出现后的前 300 毫秒内）。在噪声中，EEG 效应发生得较晚，涉及多个同时激活的区域。总的来说，我们发现了证据——尤其是在行为数据中——支持了先前的说法，即背景噪声的存在会导致更依赖于次词汇处理。
