Callan Daniel E, Jones Jeffery A, Callan Akiko M, Akahane-Yamada Reiko
Human Information Science Laboratories, ATR International, Kyoto, Japan.
Neuroimage. 2004 Jul;22(3):1182-94. doi: 10.1016/j.neuroimage.2004.03.006.
This experiment investigates neural processes underlying perceptual identification of the same phonemes for native- and second-language speakers. A model is proposed implicating the use of articulatory-auditory and articulatory-orosensory mappings to facilitate perceptual identification under conditions in which the phonetic contrast is ambiguous, as in the case of second-language speakers. In contrast, native-language speakers are predicted to use auditory-based phonetic representations to a greater extent for perceptual identification than second-language speakers. The English /r-l/ phonetic contrast, although easy for native English speakers, is extremely difficult for native Japanese speakers who learned English as a second language after childhood. Twenty-two native English and twenty-two native Japanese speakers participated in this study. While undergoing event-related fMRI, subjects were aurally presented with syllables starting with a /r/, /l/, or a vowel and were required to rapidly identify the phoneme perceived by pushing one of three buttons with the left thumb. Consistent with the proposed model, the results show greater activity for second- over native-language speakers during perceptual identification of /r/ and /l/ relative to vowels in brain regions implicated with instantiating forward and inverse articulatory-auditory articulatory-orosensory models [Broca's area, anterior insula, anterior superior temporal sulcus/gyrus (STS/G), planum temporale (PT), superior temporal parietal area (Stp), SMG, and cerebellum]. The results further show that activity in brain regions implicated with instantiating these internal models is correlated with better /r/ and /l/ identification performance for second-language speakers. Greater activity found for native-language speakers especially in the anterior STG/S for /r/ and /l/ perceptual identification is consistent with the hypothesis that native-language speakers use auditory phonetic representations more extensively than second-language speakers.
本实验研究了母语者和第二语言学习者对相同音素进行感知识别的神经过程。提出了一个模型，该模型认为在语音对比模糊的情况下（如第二语言学习者的情况），使用发音-听觉和发音-口部感觉映射来促进感知识别。相比之下，预计母语者在感知识别中比第二语言学习者更广泛地使用基于听觉的语音表征。英语/r-l/语音对比，虽然对以英语为母语的人来说很容易，但对童年后将英语作为第二语言学习的以日语为母语的人来说却极其困难。22名以英语为母语者和22名以日语为母语者参与了本研究。在进行事件相关功能磁共振成像时，向受试者听觉呈现以/r/、/l/或元音开头的音节，并要求他们用左手拇指按下三个按钮之一，快速识别所感知的音素。与所提出的模型一致，结果显示，在与实例化正向和反向发音-听觉、发音-口部感觉模型相关的脑区（布洛卡区、前岛叶、颞上沟/回前部、颞平面、颞顶叶上部区域、顶下小叶和小脑）中，第二语言学习者在/r/和/l/相对于元音的感知识别过程中比母语者表现出更强活动。结果还进一步表明，与实例化这些内部模型相关的脑区活动与第二语言学习者更好的/r/和/l/识别表现相关。母语者在/r/和/l/感知识别过程中，尤其是在前颞上回/颞上沟中发现的更强活动，与母语者比第二语言学习者更广泛地使用听觉语音表征这一假设一致。
