Rapid learning of a phonemic discrimination in the first hours of life

Abstract

Human neonates can discriminate phonemes, but the neural mechanism underlying this ability is poorly understood. Here we show that the neonatal brain can learn to discriminate natural vowels from backward vowels, a contrast unlikely to have been learnt in the womb. Using functional near-infrared spectroscopy, we examined the neuroplastic changes caused by 5 h of postnatal exposure to random sequences of natural and reversed (backward) vowels (T1), and again 2 h later (T2). Neonates in the experimental group were trained with the same stimuli as those used at T1 and T2. Compared with controls, infants in the experimental group showed shorter haemodynamic response latencies for forward vs backward vowels at T1, maximally over the inferior frontal region. At T2, neural activity differentially increased, maximally over superior temporal regions and the left inferior parietal region. Neonates thus exhibit ultra-fast tuning to natural phonemes in the first hours after birth.

Does Electrophysiological Maturation Shape Language Acquisition?

“…If the acoustic filter of the womb is the only constraint on learning, fetuses should be able to exploit their prenatal exposure to segmentation cues. But this is not the case: Although newborns show phonemic perceptual learning for individually presented vowels (Wu et al, 2022), they do not yet show the ability to segment fast speech sounds from continuous speech (Bijeljac-Babic et al, 1993), indicating a maturational rather than environmental constraint on the processing of fast modulations in speech, as this information was already available in utero.…”

Scripts’ influence on reading processes and cognition: a preamble

“…It is not surprising that reading/writing is built on spoken language as by the time children are introduced to literacy skills they have already mastered the spoken language to a large extent. Modern research suggests that newborn infants develop initial language-related skills shortly after birth (Wu et al, 2022). Eye movement studies also suggest that eye movements during text reading align with the rate of speech production (Gagl et al, 2022).…”

Neonatal sensitivity to vocal emotions: A developmental change at 37 weeks of gestational age

“…Additionally, the inclusion of non-speech emotional materials may offer insights into the potential right lateralization of emotional processing in the neonatal brain. While prior studies (including some cited herein) have identified right lateralization for emotional processing in full-term neonates (Cheng et al, 2012; Zhang et al, 2019;see Bisiacchi & Cainelli, 2022 for a comprehensive review), the introduction of non-speech materials can help disentangle the confounding effects of left lateralization, which is associated with language processing and has been identified in both preterm (Mahmoudzadeh et al, 2013) and full-term neonates (Kotilahti et al, 2010; May et al, 2018; Peña et al, 2003; Sato et al, 2012; Vannasing et al, 2016; Wu et al, 2022).…”