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Language learning in monolingual and bilingual infants: Evidence from electrophysiological and optical signals

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Language learning in infants under analysis

Recent studies show that infants can master two languages with the same ease as their monolingual peers. European researchers have applied sophisticated neuroscience to see if bilingual toddlers really have it that easy.


Previous studies suggest that the challenging task of associating two words with one object led to a delay in processing as a result of the higher cognitive load. As more recent studies have overturned this theory, the INFANTBILINGUALBRAIN (Language learning in monolingual and bilingual infants: evidence from electrophysiological and optical signals) project has investigated how bi- and mono-lingual infants learn their languages and which area of the brain they use. Recruiting six and eighteen-month old infants – German monolingual and bilingual German and Italian speakers – the researchers performed a language learning study consisting of a pretest, a training, and a posttest. During the pre- and posttest they acoustically presented phonotactically native (German) and non-native (i.e. Slovak) rules embedded in pseudowords for both groups. Phonotactics describes the possible phoneme combinations of words in a specific language. During training, some native and non-native pseudowords were correctly and incorrectly paired with pseudo-objects. To track neural processing, INFANTBILINGUALBRAIN used electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) simultaneously. EEG can detect fast linguistic processing mechanisms and fNIRS identifies the areas of the brain involved. Results showed that both groups learned pseudowords indicating they can learn from semantic training. However, fNIRS confirmed previous studies that initially both brain hemispheres are necessary but once competent, only one is used, as in adult processing. Bilinguals seemed to benefit from the semantic training for familiar rules and from passive listening for foreign language rules. They also tended to show a more adult-like left-hemispheric lateralisation, impressive at this young age. However, especially 18-month-old bilinguals showed difficulties with ambitious semantic training and in some cases used both hemispheres or showed no modulation. Interestingly, the bilinguals EEG results at 18 months of age showed a stronger sensitivity for untrained items than monolinguals. This indicates benefits from the passive acoustic presentation rather than from the difficult semantic training. INFANTBILINGUALBRAIN findings have widespread social implications as they indicate real differences in the way mono- and bi-lingual children learn languages. Age is significant and must be taken into account when providing language learning settings for each group. Day nurseries, playschools and even home environment could apply these research results for maximum benefits in language for the young learner.


Language, infants, monolingual, bilingual, semantic training, passive listening

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