The ability to differentiate between two languages sets the stage for bilingual learning. Infants can discriminate languages when hearing long passages, but language switches often occur on short time scales with few cues to language identity. As bilingual infants begin learning sequences of sounds and words, how do they detect the dynamics of two languages? In two studies using the head-turn preference procedure, we investigated whether infants (n = 44) can discriminate languages at the level of individual words. In Study 1, bilingual and monolingual 8- to 12-month-olds were tested on their detection of single-word language switching in lists of words (e.g., “dog… lait [fr. milk]”). In Study 2, they were tested on language switching within sentences (e.g., “Do you like the lait?”). We found that infants were unable to detect language switching in lists of words, but the results were inconclusive about infants’ ability to detect language switching within sentences. No differences were observed between bilinguals and monolinguals. Given that bilingual proficiency eventually requires detection of sound sequences across two languages, more research will be needed to conclusively understand when and how this skill emerges. Materials, data, and analysis scripts are available at https://osf.io/9dtwn/.

中文翻译：

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微调语言辨别：双语和单语婴儿对语言转换的检测

区分两种语言的能力为双语学习奠定了基础。婴儿在听到长篇文章时可以区分语言，但语言转换通常发生在很短的时间尺度上，几乎没有语言认同的线索。当双语婴儿开始学习声音和单词的序列时，他们如何检测两种语言的动态？在使用转头偏好程序的两项研究中，我们调查了婴儿 ( n  = 44) 是否可以在单个单词的水平上区分语言。在研究 1 中，测试了双语和单语 8 至 12 个月大的孩子在单词列表中检测单个单词的语言转换（例如，“dog... lait [fr. milk]”）。在研究 2 中，他们接受了句子内语言转换的测试（例如，“你喜欢莱特？”）。我们发现婴儿无法检测单词列表中的语言转换，但结果对于婴儿检测句子中语言转换的能力尚无定论。双语者和单语者之间没有观察到差异。鉴于双语能力最终需要检测两种语言的声音序列，需要更多的研究来最终了解这种技能何时以及如何出现。材料、数据和分析脚本可在 https://osf.io/9dtwn/ 获得。