Department of Psychology, Florida International University, Miami, FL 33199, USA.
Department of Psychology, Florida International University, Miami, FL 33199, USA.
J Exp Child Psychol. 2019 Jul;183:295-309. doi: 10.1016/j.jecp.2019.02.008. Epub 2019 Apr 4.
Prosody, or the intonation contours of speech, conveys emotion and intention to the listener and provides infants with an early basis for detecting meaning in speech. Infant-directed speech (IDS) is characterized by exaggerated prosody, slower tempo, and elongated pauses, all amodal properties detectable across the face and voice. Although speech is an audiovisual event, it has been studied primarily as a unimodal auditory stream without the synchronized dynamic face of the speaker. According to the intersensory redundancy hypothesis, redundancy across the senses facilitates perceptual learning of amodal information, including prosody. We predicted that young infants who are still learning to discriminate and categorize prosodic information would detect prosodic changes better in the presence of intersensory redundancy (i.e., synchronous audiovisual speech) than in its absence (i.e., unimodal auditory or asynchronous audiovisual speech). To test this hypothesis, 72 4-month-old infants were habituated to recordings of women reciting passages in IDS with prosody conveying either approval or prohibition and then were tested with recordings of a novel passage with either a change or no change in prosody. Infants who received bimodal synchronous stimulation exhibited significant visual recovery to the novel passage with a change in prosody, but not to a novel passage with no change in prosody. Infants in the unimodal auditory and bimodal asynchronous conditions did not exhibit visual recovery in either condition. Results support the hypothesis that intersensory redundancy facilitates detection and abstraction of invariant prosody across changes in linguistic content and likely serves as an early foundation for the detection of meaning in fluent speech.
韵律，或言语的语调轮廓，向听者传达情感和意图，并为婴儿提供了一个早期的基础，用于检测言语中的意义。婴儿指向性言语（IDS）的特点是夸张的韵律、较慢的节奏和延长的停顿，所有这些非模态特征都可以在面部和声音上检测到。尽管言语是一种视听事件，但它主要作为一种单一模态的听觉流进行研究，而没有说话者同步的动态面部。根据感觉冗余假说，跨感觉的冗余有助于包括韵律在内的非模态信息的感知学习。我们预测，仍在学习区分和分类韵律信息的幼儿在存在感觉冗余（即同步视听言语）的情况下比不存在感觉冗余（即单一模态听觉或异步视听言语）的情况下能更好地检测到韵律变化。为了验证这一假设，72 名 4 个月大的婴儿习惯了女性用 IDS 朗读带有表达赞成或禁止信息的段落，然后用带有或不带有韵律变化的新段落进行测试。接受双模态同步刺激的婴儿在带有韵律变化的新段落中表现出显著的视觉恢复，但在没有韵律变化的新段落中则没有。在单一模态听觉和双模态异步条件下的婴儿在两种条件下都没有表现出视觉恢复。结果支持这样一种假设，即感觉冗余有助于在语言内容变化的情况下检测和抽象不变的韵律，并可能作为在流畅言语中检测意义的早期基础。
