School of Health Sciences, City University, London, UK; Department of Psychological Sciences, Birkbeck College, London, UK.
Dev Sci. 2014 Jan;17(1):110-24. doi: 10.1111/desc.12098. Epub 2013 Oct 31.
Being able to see a talking face confers a considerable advantage for speech perception in adulthood. However, behavioural data currently suggest that children fail to make full use of these available visual speech cues until age 8 or 9. This is particularly surprising given the potential utility of multiple informational cues during language learning. We therefore explored this at the neural level. The event-related potential (ERP) technique has been used to assess the mechanisms of audio-visual speech perception in adults, with visual cues reliably modulating auditory ERP responses to speech. Previous work has shown congruence-dependent shortening of auditory N1/P2 latency and congruence-independent attenuation of amplitude in the presence of auditory and visual speech signals, compared to auditory alone. The aim of this study was to chart the development of these well-established modulatory effects over mid-to-late childhood. Experiment 1 employed an adult sample to validate a child-friendly stimulus set and paradigm by replicating previously observed effects of N1/P2 amplitude and latency modulation by visual speech cues; it also revealed greater attenuation of component amplitude given incongruent audio-visual stimuli, pointing to a new interpretation of the amplitude modulation effect. Experiment 2 used the same paradigm to map cross-sectional developmental change in these ERP responses between 6 and 11 years of age. The effect of amplitude modulation by visual cues emerged over development, while the effect of latency modulation was stable over the child sample. These data suggest that auditory ERP modulation by visual speech represents separable underlying cognitive processes, some of which show earlier maturation than others over the course of development.
能够看到说话的人脸会给成年人的言语感知带来很大的优势。然而，目前的行为数据表明，儿童直到 8 或 9 岁才能充分利用这些可用的视觉言语线索。这尤其令人惊讶，因为在语言学习过程中，多种信息线索具有潜在的效用。因此，我们在神经水平上探索了这一点。事件相关电位 (ERP) 技术已被用于评估成人视听言语感知的机制，视觉线索可靠地调节听觉 ERP 对言语的反应。先前的工作表明，与仅听觉相比，在存在听觉和视觉言语信号的情况下，听觉 N1/P2 潜伏期的一致性相关缩短，以及振幅的一致性独立衰减。本研究的目的是绘制这些成熟的调制效应在从中年到晚期儿童发育过程中的发展情况。实验 1 采用成人样本验证了一种适合儿童的刺激集和范式，复制了先前观察到的视觉言语线索对 N1/P2 振幅和潜伏期调制的影响；它还揭示了在不一致的视听刺激下，成分振幅的衰减更大，这指向了对振幅调制效应的新解释。实验 2 使用相同的范式，在 6 至 11 岁之间的这些 ERP 反应中映射了横断面的发展变化。视觉线索的振幅调制效应随着发育而出现，而潜伏期调制效应在儿童样本中是稳定的。这些数据表明，听觉 ERP 对视觉言语的调制代表了可分离的潜在认知过程，其中一些过程在发育过程中比其他过程更早成熟。
