Suchergebnisse

AbstractThe speech register that adults especially caregivers use when interacting with infants and toddlers, that is, infant‐directed speech (IDS) or baby talk, has been reported to facilitate language development throughout the early years. However, the neural mechanisms as well as why IDS results in such a developmental faciliatory effect remain to be investigated. The current study uses functional near‐infrared spectroscopy (fNIRS) to evaluate two alternative hypotheses of such a facilitative effect, that IDS serves to enhance linguistic contrastiveness or to attract the child's attention. Behavioral and fNIRS data were acquired from twenty‐seven Cantonese‐learning toddlers 15–20 months of age when their parents spoke to them in either an IDS or adult‐directed speech (ADS) register in a naturalistic task in which the child learned four disyllabic pseudowords. fNIRS results showed significantly greater neural responses to IDS than ADS register in the left dorsolateral prefrontal cortex (L‐dlPFC), but opposite response patterns in the bilateral inferior frontal gyrus (IFG). The differences in fNIRS responses to IDS and to ADS in the L‐dlPFC and the left parietal cortex (L‐PC) showed significantly positive correlations with the differences in the behavioral word‐learning performance of toddlers. The same fNIRS measures in the L‐dlPFC and right PC (R‐PC) of toddlers were significantly correlated with pitch range differences of parents between the two speech conditions. Together, our results suggest that the dynamic prosody in IDS increased toddlers' attention through greater involvement of the left frontoparietal network that facilitated word learning, compared to ADS.Research Highlights
This study for the first time examined the neural mechanisms of how infant‐directed speech (IDS) facilitates word learning in toddlers.
Using fNIRS, we identified the cortical regions that were directly involved in IDS processing.
Our results suggest that IDS facilitates word learning by engaging a right‐lateralized prosody processing and top‐down attentional mechanisms in the left frontoparietal networks.
The language network including the inferior frontal gyrus and temporal cortex was not directly involved in IDS processing to support word learning.

AbstractA form‐preparation task in the language production field was adopted to examine output phonological representations in Chinese dyslexia and their susceptibility to training. Forty‐one Chinese children with dyslexia (7–11 years old) and 36 chronological age controls completed this task. The controls demonstrated a marginally significant syllable facilitation effect (d = −0.13), indicating their use of syllable‐sized phonological representations during speech production, while the group with dyslexia showed a significantly different pattern (d = 0.04), opposite to the direction of a facilitation effect. The children with dyslexia were then randomly assigned to either metalinguistic training (N = 22) or working memory training (N = 19). Only the metalinguistic training subgroup demonstrated a significant syllable facilitation effect afterward (metalinguistic: d = −0.13; working memory: d = −0.01). The results suggest the presence of a phonological representation deficit at the syllable level in Chinese dyslexia and its possible remediation by metalinguistic training. Such a phonological deficit in readers of a logographic script strongly supports the impaired phonological representation view of developmental dyslexia. A video abstract of this article can be viewed at https://youtu.be/zT2Be0xMkh0.

AbstractWe report the findings of a multi‐language and multi‐lab investigation of young infants' ability to discriminate lexical tones as a function of their native language, age and language experience, as well as of tone properties. Given the high prevalence of lexical tones across human languages, understanding lexical tone acquisition is fundamental for comprehensive theories of language learning. While there are some similarities between the developmental course of lexical tone perception and that of vowels and consonants, findings for lexical tones tend to vary greatly across different laboratories. To reconcile these differences and to assess the developmental trajectory of native and non‐native perception of tone contrasts, this study employed a single experimental paradigm with the same two pairs of Cantonese tone contrasts (perceptually similar vs. distinct) across 13 laboratories in Asia‐Pacific, Europe and North‐America testing 5‐, 10‐ and 17‐month‐old monolingual (tone, pitch‐accent, non‐tone) and bilingual (tone/non‐tone, non‐tone/non‐tone) infants. Across the age range and language backgrounds, infants who were not exposed to Cantonese showed robust discrimination of the two non‐native lexical tone contrasts. Contrary to this overall finding, the statistical model assessing native discrimination by Cantonese‐learning infants failed to yield significant effects. These findings indicate that lexical tone sensitivity is maintained from 5 to 17 months in infants acquiring tone and non‐tone languages, challenging the generalisability of the existing theoretical accounts of perceptual narrowing in the first months of life.Research Highlights
This is a multi‐language and multi‐lab investigation of young infants' ability to discriminate lexical tones.
This study included data from 13 laboratories testing 5‐, 10‐, and 17‐month‐old monolingual (tone, pitch‐accent, non‐tone) and bilingual (tone/non‐tone, non‐tone/non‐tone) infants.
Overall, infants discriminated a perceptually similar and a distinct non‐native tone contrast, although there was no evidence of a native tone‐language advantage in discrimination.
These results demonstrate maintenance of tone discrimination throughout development.