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This months language lab looks at some of the neuroscience studies behind bilingualism.

 Speech and language therapists working in schools across the UK, find that the children they work with speak a variety of different languages. Here at Therapy Network Ltd we have summarised the most recent research to help provide an evidenced based back-drop to bear in mind, when supporting bilingualism.

Over 50% of people are defined as bilingual or plurilingual. Although the degree of competence and the frequency of use vary considerably between children.

There have been a large number of studies, which have addressed this subject. These studies have attempted to:

  1. Isolate and pinpoint the neural basis of bilingualism.
  2. Clarify the nature and representation of the cognitive processes underpinning the learning and use of the different languages.
  3. Understand the functional and anatomical relationship between languages.


  • Auditory Comprehension of texts
  • Word productions (repetition and rhymes, naming at single word level)
  • Phonetic tasks
  • Gene mapping

All these studies have provided an essential contribution to understanding the neurological and functional bases of the process of learning a first language (L1) and a second language (L2). Essentially, showing whether two spoken languages may correspond with greater variability of anatomical representation.

Factors to consider as a speech therapist working with bilingual children.

 Age of Acquisition/ Language Exposure

Children from birth have a greater proficiency in some tasks and show similar activation to L1 learners. Those L2 learners’ acquiring languages after 6 years old show a greater degree of activation in other different areas of the brain. This suggests additional neural involvement. However, on some tasks no differences were found irrespective of age or exposure.

 Phonetic Characteristics

Other studies have shown that children from one language, who are adopted by families from another language origin (between the ages of 7-9 yrs) with no further exposure to their L1 language, demonstrate a complete substitution of L1 by L2 in tasks such as phoneme discrimination and identification.

Gene Studies

Correlations between linguistic differences and in gene variations in various populations are usually the result of historical and geographical factors. Molecular genetics have revealed that the degree of correlation between the presence of specific alleles and the use of tonal language does not seem to be tied to historical or geographical factors, but rather the presence of specific alleles facilitating the acquisition of the linguistic characteristics present in tonal languages, which in turn, influences the process of linguistic mutation through repeated cultural transmission.


There is considerable neural overlay between languages spoken by bilingual and multi-lingual individuals. Word, sound and sentence elements are processed by the same areas of the brain for both L1 and L2+ learners.

However, the degree of overlap is directly proportional to the level of linguistic competence in the two languages and the age the individual acquired L2.


  1. Children acquiring L1 & L2 from birth to 6 years show the same activation patterns in the same region of the brain.
  1. L2 language learnt later in life requires the activation of other areas of the brain, particular for sentence tasks.

These results emphasise the effect of age acquisition on the neural underpinnings of grammatical processing. (Perani & Abutalebi 2005).

However, it is still not clear, to what extent the degree of competence in L2 contributes to the activation of L1. On the contrary, how much L1 influences the processes of L2.

For further reading go to:


Denes Gian Franco, (2009) The neurological bases and functional architecture of bilingualism Psychological press 2009

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