Purdue University West Lafayette, IN, USA.
Front Psychol. 2012 Nov 2;3:448. doi: 10.3389/fpsyg.2012.00448. eCollection 2012.
There is a substantial literature describing how infants become more sensitive to differences between native phonemes (sounds that are both present and meaningful in the input) and less sensitive to differences between non-native phonemes (sounds that are neither present nor meaningful in the input) over the course of development. Here, we review an emergent strand of literature that gives a more nuanced notion of the problem of sound category learning. This research documents infants' discovery of phonological status, signaled by a decrease in sensitivity to sounds that map onto the same phonemic category vs. different phonemic categories. The former phones are present in the input, but their difference does not cue meaning distinctions because they are tied to one and the same phoneme. For example, the diphthong I in I'm should map to the same underlying category as the diphthong in I'd, despite the fact that the first vowel is nasal and the second oral. Because such pairs of sounds are processed differently than those than map onto different phonemes by adult speakers, the learner has to come to treat them differently as well. Interestingly, there is some evidence that infants' sensitivity to dimensions that are allophonic in the ambient language declines as early as 11 months. We lay out behavioral research, corpora analyses, and computational work which sheds light on how infants achieve this feat at such a young age. Collectively, this work suggests that the computation of complementary distribution and the calculation of phonetic similarity operate in concert to guide infants toward a functional interpretation of sounds that are present in the input, yet not lexically contrastive. In addition to reviewing this literature, we discuss broader implications for other fundamental theoretical and empirical questions.
有大量文献描述了婴儿在发展过程中如何变得对母语音位（输入中既有意义又存在的音）的差异更加敏感，而对非母语音位（输入中既不存在也没有意义的音）的差异不那么敏感。在这里，我们回顾了一个新兴的文献系列，该文献对音位类别学习问题提出了更细致的概念。这项研究记录了婴儿对语音状态的发现，即对映射到相同音位类别与不同音位类别的声音的敏感性降低。前者在输入中存在，但它们的区别并不能提示意义区别，因为它们与同一个音位相关联。例如，在 I'm 中的双元音 I 应该与在 I'd 中的双元音映射到相同的底层类别，尽管第一个元音是鼻音，第二个元音是口腔音。由于这些双元音的处理方式与成人说话者不同，因此学习者也必须以不同的方式对待它们。有趣的是，有一些证据表明，婴儿对环境语言中变音的维度的敏感性早在 11 个月大时就下降了。我们列出了行为研究、语料库分析和计算工作，这些研究为我们提供了关于婴儿如何在如此年幼的年龄就能完成这一壮举的线索。总的来说，这项工作表明，互补分布的计算和语音相似性的计算协同作用，引导婴儿对输入中存在但不具有词汇对比的声音进行功能解释。除了回顾这一文献，我们还讨论了它对其他基本理论和实证问题的更广泛影响。
