Functional neuroimaging study on the relationship between infant-directed vocabulary and development of speech perception and production in infants

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K12451
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Cognitive science
• Research Institution: Nagaoka University of Technology (2017-2019); Institute of Physical and Chemical Research (2016)
• Principal Investigator: Akimoto Yoritaka 長岡技術科学大学, 工学研究科, 助教 (00555245)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 言語発達 / 対乳児発話 / 育児語型韻律 / 子音の弁別

Outline of Final Research Achievements

Experiments on native and non-native consonant discrimination and perception of prosodic form of infant-directed vocabulary were conducted in 5-month- and 9-month-old infants. Furthermore, experimentation on the production of infant-directed speech was conducted in adult participants.
The results demonstrated the following: (1) infants’ performance and brain activities for consonant discrimination were not only dependent on nativity of the speech stimuli but also on the directed change of consonants (e.g., from /l/ to /r/); (2) five-month-old infants displayed greater brain activity for prosodic forms of the infant-directed vocabulary than the control stimuli (not infant-directed vocabulary), whereas 9-month-old infants showed the opposite pattern; (3) brain activity during the production of infant-directed speech was different from that during the production of adult-directed speech in the right frontal lobe.

Free Research Field

認知神経科学

Academic Significance and Societal Importance of the Research Achievements

乳児に対して話しかける際には、韻律の強調や特殊な語彙の使用など、大人に対する発話とは異なった特徴的な話し方（対乳児発話）になることが知られている。この対乳児発話は乳児にとって認知しやすく、また言語発達に寄与することが報告されているが、その多くは欧米の言語を対象とした研究である。
本研究の成果は、日本語の育児語に多く存在する韻律のパターンが乳児の言語発達に寄与している可能性を示唆するものであり、対乳児発話の機能について欧米以外の言語から迫る貴重な知見である。