Early EEG correlates of word frequency and contextual predictability in reading

Previous research into written language comprehension has been equivocal as to whether word frequency and contextual predictability effects share an early time course of processing. Target word frequency (low, high) and its predictability from prior context (low, high) were manipulated across two-sentence passages. Context sentences were presented in full, followed by word-by-word presentation (300 ms SOA) of target sentences. ERPs were analysed across left-to-right and anterior-to-posterior regions of interest within intervals from 50 to 550 ms post-stimulus. The onset of significant predictability effects (50–80 ms) preceded that of frequency (P1, 80–120 ms), while both main effects were generally sustained through the N400 (350–550 ms). Critically, the frequency-predictability interaction became significant in the P1 and was sustained through the N400, although the specific configuration of effects differed across components. The pattern of findings supports an early, chronometric locus of contextual predictability in recognising words during reading.

过往针对书面语言理解的研究，在词频与语境可预测性效应是否共享加工的早期时间进程这一问题上尚无定论。研究者在双句语篇中，对目标词词频（高、低）以及其由前文语境推导得到的可预测性程度（高、低）进行了操纵：先完整呈现语境句，随后对目标句进行逐词呈现（刺激呈现异步性SOA为300毫秒）。在刺激后50至550毫秒的时间窗口内，对左右侧及前后侧感兴趣区的事件相关电位（Event-Related Potentials, ERPs）开展分析。研究结果显示，显著的语境可预测性效应出现于50–80毫秒，早于词频效应（P1成分，80–120毫秒）；且两种主效应均在N400时段（350–550毫秒）持续存在。尤为关键的是，尽管不同脑电成分对应的效应模式存在差异，但词频与语境可预测性的交互作用在P1成分中即达到显著水平，并持续贯穿N400时段。上述研究结果支持了“阅读过程中词汇识别阶段存在语境可预测性的早期计时加工位点”这一结论。