The “Perceptual Wedge Hypothesis” as the Basis for Bilingual Babies’ Phonetic Processing Advantage:

Updated: Dec 16, 2019

Apr 18, 2014


Being bilingual is good for your brain! Learn more about why monolingual isn’t the default setting for the brain in Petitto, Bergens, Kovelman, Dubins, Jasinka, & Shalinksy (2012).


Babies are able to differentiate the sounds and movements in their early environment from the bits of linguistic information that they will eventually use to build into words, phrases, and sentences.  This ability is known as phonetic discrimination, and it is how babies discover the unique set of phonetic units (sounds or parts of signs) that make up the words or signs in their language. Research has shown that babies under six months of age are able to discriminate all of the phonetic contrasts of all the languages in the world that they are exposed to, even if they never heard them before. By the age of 10-12 months, they lose this ability and become more attuned to the phonetic units of their native language.


Some research has suggested bilingual exposure can cause language delay. To investigate this claim, researchers analyzed how specific areas of the brain responded to native and non-native phonetic units for monolingual and bilingual babies. The results show that bilingual babies and monolingual babies use the same brain tissue in early language processing as is found in adults. Intriguingly, researchers also found that while older (12 months) monolingual babies had a more “closed” sensitivity to non-native phonetic contrasts, bilingual babies retained this sensitivity.   The research team found that bilingual babies do not suffer any negative effects of dual language exposure. On the contrary, bilingual babies appear to benefit in the early development of healthy language processing.  Being monolingual does not appear to be the default or normal “setting” for the developing brain.


The “Perceptual Wedge Hypothesis” as the Basis for Bilingual Babies’ Phonetic Processing Advantage: New Insights from fNIRS Brain Imaging. Petitto, Bergens, Kovelman, Dubins, Jasinka, & Shalinksy (2012). Brain & Language, 121 (2), 130 – 143. Please see Petitto’s published papers and abstracts here.


Keywords: Language Acquisition, bilingualism

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