Laboratory for Language Development, RIKEN Center for Brain Science, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan.
Laboratory for Language Development, RIKEN Center for Brain Science, 2-1, Hirosawa, Wako-shi, Saitama 351-0198, Japan; Graduate School of Technology, Industrial and Social Sciences, Tokushima University, 1-1 Minamijosanjima, Tokushima 770-8502, Japan.
Cognition. 2021 Aug;213:104711. doi: 10.1016/j.cognition.2021.104711. Epub 2021 Apr 12.
Songs and speech play central roles in early caretaker-infant communicative interactions, which are crucial for infants' cognitive, social, and emotional development. Compared to speech development, however, much less is known about how infants process songs or how songs affect their development. Lyrics and melody are two key components of songs, and much of the research on song processing has examined how the two components of the songs are processed. The current study focused on the roles of lyrics and melody in song perception, by examining developmental patterns and the ways in which lyrics and melody are processed in the infants' brains using near-infrared spectroscopy (NIRS). The results revealed that developmental changes occur in infants' processing of lyrics and melody in a similar timeline as perceptual reorganization, that is, from 4.5 and 12 months of age. We found that 4.5-month-olds showed a right hemispheric advantage in the processing of songs that underwent a change in either lyrics or melodies. Conversely, 12-month-olds showed significantly higher activation bilaterally when lyrics and melody changed at the same time. These results suggest that 4.5-month-olds processed songs in the same manner as music without lyrics. Moreover, 12-month-olds processed lyrics and melody in an interactive manner, a sign of a more mature processing method. These findings highlight the importance of investigating the independent development of music and language, and also considering the relationship between speech and song, lyrics and melody in song, and speech and music more broadly.
歌曲和言语在早期照顾者与婴儿的交流互动中起着核心作用，这对婴儿的认知、社会和情感发展至关重要。然而，与言语发展相比，人们对婴儿如何处理歌曲或歌曲如何影响他们的发展知之甚少。歌词和旋律是歌曲的两个关键组成部分，因此，大多数关于歌曲处理的研究都集中在这两个部分如何被处理上。本研究通过使用近红外光谱（NIRS）检查歌词和旋律在婴儿大脑中的处理方式，关注歌词和旋律在歌曲感知中的作用，以探索歌词和旋律在歌曲感知中的作用。研究结果表明，在与感知重组相似的时间线上，即 4.5 个月至 12 个月时，婴儿对歌词和旋律的处理会发生发育变化。我们发现，4.5 个月大的婴儿在处理歌词或旋律发生变化的歌曲时，右半球有优势。相反，当歌词和旋律同时发生变化时，12 个月大的婴儿双侧的激活明显更高。这些结果表明，4.5 个月大的婴儿以与无歌词的音乐相同的方式处理歌曲。此外，12 个月大的婴儿以交互的方式处理歌词和旋律，这是一种更成熟的处理方式的标志。这些发现强调了研究音乐和语言的独立发展以及更广泛地考虑言语和歌曲、歌词和旋律在歌曲中的关系以及言语和音乐之间关系的重要性。
