Laboratorio de Neurociencias Cognitivas, Escuela de Psicología, Pontificia Universidad Católica de Chile, 7820436 Santiago, Chile.
J Neurosci. 2012 Aug 15;32(33):11159-63. doi: 10.1523/JNEUROSCI.6516-11.2012.
Critical periods in language acquisition have been discussed primarily with reference to studies of people who are deaf or bilingual. Here, we provide evidence on the opening of sensitivity to the linguistic environment by studying the response to a change of phoneme at a native and nonnative phonetic boundary in full-term and preterm human infants using event-related potentials. Full-term infants show a decline in their discrimination of nonnative phonetic contrasts between 9 and 12 months of age. Because the womb is a high-frequency filter, many phonemes are strongly degraded in utero. Preterm infants thus benefit from earlier and richer exposure to broadcast speech. We find that preterms do not take advantage of this enriched linguistic environment: the decrease in amplitude of the mismatch response to a nonnative change of phoneme at the end of the first year of life was dependent on maturational age and not on the duration of exposure to broadcast speech. The shaping of phonological representations by the environment is thus strongly constrained by brain maturation factors.
语言习得的关键期主要是通过对聋人或双语者的研究来讨论的。在这里，我们通过使用事件相关电位来研究足月和早产儿对母语和非母语语音边界处音位变化的反应，为语言环境敏感性的开启提供了证据。足月婴儿在 9 到 12 个月大时，对非母语语音对比的辨别能力下降。由于子宫是一个高频滤波器，许多音素在子宫内都受到强烈的削弱。早产儿因此受益于更早和更丰富的广播语音暴露。我们发现早产儿并没有利用这种丰富的语言环境：对非母语音位变化的不匹配反应幅度的下降在生命的第一年与成熟年龄有关，而与广播语音暴露时间无关。因此，环境对语音表征的塑造受到大脑成熟因素的强烈限制。
