Lloyd-Fox Sarah, Széplaki-Köllőd Borbála, Yin Jun, Csibra Gergely
Cognitive Development Center, Central European University, Budapest 1051, Hungary; Birkbeck, University of London, London WC1E 7HX, UK.
Cognitive Development Center, Central European University, Budapest 1051, Hungary.
Cortex. 2015 Sep;70:35-48. doi: 10.1016/j.cortex.2015.02.005. Epub 2015 Feb 28.
Human interactions are guided by continuous communication among the parties involved, in which verbal communication plays a primary role. However, speech does not necessarily reveal to whom it is addressed, especially for young infants who are unable to decode its semantic content. To overcome such difficulty, adults often explicitly mark their communication as infant-directed. In the present study we investigated whether ostensive signals, which would disambiguate the infant as the addressee of a communicative act, would modulate the brain responses of 6-month-old infants to speech and gestures in an ecologically valid setting. In Experiment 1, we tested whether the gaze direction of the speaker modulates cortical responses to infant-direct speech. To provide a naturalistic environment, two infants and their parents participated at the same time. In Experiment 2, we tested whether a similar modulation of the cortical response would be obtained by varying the intonation (infant versus adult directed speech) of the speech during face-to-face communication, one on one. The results of both experiments indicated that only the combination of ostensive signals (infant directed speech and direct gaze) led to enhanced brain activation. This effect was indicated by responses localized in regions known to be involved in processing auditory and visual aspects of social communication. This study also demonstrated the potential of fNIRS as a tool for studying neural responses in naturalistic scenarios, and for simultaneous measurement of brain function in multiple participants.
人际互动是由参与各方之间的持续沟通所引导的，其中言语交流起着主要作用。然而，言语并不一定能表明它是针对谁的，特别是对于那些无法解读其语义内容的幼儿来说。为了克服这一困难，成年人通常会明确地将他们的交流标记为针对婴儿的。在本研究中，我们调查了明示信号（它能消除婴儿作为交际行为受话人的歧义）是否会在生态有效环境中调节6个月大婴儿对言语和手势的大脑反应。在实验1中，我们测试了说话者的注视方向是否会调节对婴儿导向言语的皮层反应。为了提供一个自然的环境，两个婴儿及其父母同时参与。在实验2中，我们测试了在一对一的面对面交流中，通过改变言语的语调（婴儿导向言语与成人导向言语）是否会获得类似的皮层反应调节。两个实验的结果都表明，只有明示信号（婴儿导向言语和直接注视）的组合才会导致大脑激活增强。这种效应通过位于已知参与处理社会交流的听觉和视觉方面的区域的反应得以体现。本研究还证明了功能近红外光谱技术作为一种在自然场景中研究神经反应以及同时测量多个参与者脑功能的工具的潜力。
