The Effects of Second Language Acquisition on the Brain

January 10, 2019 — by Shehab Ali0



The Effects of Second Language Acquisition on the Brain

January 10, 2019 — by Shehab Ali0

In 1948, in ‘Human Knowledge: Its Scope and Limits,’ philosopher Bertrand Russell wrote, ‘Language serves not only to express thoughts, but to make possible thoughts which could not exist without it.’ Language is not only a tool for communication but, it functions primarily as a system of thought.

Language remains one of the most peculiar characteristics of human beings. The male nightingale can emit more than two hundred different song types to highlight its ability to improvise. These songs, however, are semantically quite poor. Several animal species, like bees, have intricate systems of communications, and yet it pales in comparison to the human ability to master not one, but many languages, all of which can be used to express an infinite variety of structurally different sentences.

In recent years, there has been an explosion of research into the area of language acquisition: specifically, into the effects of bilingualism on the brain. Since infants are already born with talking readiness or pre-language, it’s impossible to compare the difference between a monolingual and a non-lingual brain. Non-lingual brains simply do not exist. As a substitute, comparing monolinguals with bilinguals could provide insights to better understand the neurobiology of language acquisition.


Neuroplasticity refers to the brain’s tendency to undergo structural reconfiguration in response to environmental stimulus, cognitive demand or behavioural experience. Recent research has begun to examine neuroplasticity as a function of language acquisition. The evidence uncovered suggests that learning and using multiple languages induces changes in brain anatomy including functional neural patterns. These changes can occur rapidly and regardless of age.

The brain is made up of two types of tissues: gray matter and white matter. Gray matter contains the cell bodies of neurons whereas white matter refers to the axon bundles that connect different regions of gray matter to each other and carry nerve impulses between neurons.  Gray matter density or volume is directly associated with general intelligence, memory, attention and language. White matter, on the other hand, governs the speed of information processing and memory recall and facilitates the travel of never impulses between neurons.

A study conducted by Stein et al. (2012) measured structural changes in the brain’s prefrontal and temporal cortices along with gray matter density, as a result of second language acquisition. The participants, who had minimal knowledge of the target language, underwent an intensive course that lasted three weeks. The researchers observed an increase in gray matter density, especially in the frontal lobes. These changes were directly attributed to second language acquisition.

Martensson et al. (2012) conducted another study targeting adult learners, specifically. The researchers observed significantly large increases in cortical thickness due to second language exposure. Increases in hippocampal volume were also noted. Both these studies concluded that language acquisition increases gray matter density and plasticity in the brain.

A third study, published in the Journal of Brain and Language, compared the white matter structure between monolinguals and Spanish-English bilingual adults living in the United States. The studies revealed that immersive learning of a second language increased neuroplasticity and white matter integrity in adult learners.

Effects on General Intelligence

Researchers at the Centre for Cognitive Ageing at the University of Edinburgh found that learning a new language improves intelligence, verbal fluency and reading. Their findings indicated that speaking more than one language had a significant effect on cognitive abilities including general intelligence and reading. The study, which was conducted across age groups, showed marked cognitive improvements in attention, focus and fluency.

Another study compared the cognitive skills and metalinguistic awareness of monolingual and bilingual children on three verbal tasks and one non-verbal executive control task, in order to examine the effects of bilingualism on brain development. Bilingual children scored significantly higher on measures of multitasking and metalinguistic awareness.

Age-Related Cognitive Decline and Dementia

Cognitive flexibility is the ability to shape thoughts and behaviour to meet internal goals as according to constant changes in environmental demands. Cognitive flexibility, which is critical for successful navigation of the demands of everyday life, declines significantly with age. New evidence, however, suggests that regularly speaking more than one language can delay age-related cognitive decline and may even delay the onset of dementia.

Psycholinguistic research demonstrated that when bilinguals attempt to use either language; the other language is also activated. Bilinguals and multilinguals are therefore under more cognitive strain since they are constantly switching between languages and suppressing the unrequired language as necessitated by context. This has been shown to strengthen general purpose executive control like task switching and delay age-related cognitive decline diseases like Alzheimer’s.

Growth of Language-Related Brain Areas

The complex process of detecting and interpreting language involves many brain regions, namely: Broca’s area, Wernicke’s area, the angular gyrus and the insular cortex. Broca’s area is necessary for the formation and expression of language; the angular gyrus assembles information in order to interpret words and concepts; Wernicke’s area processes words and word sequences according to context and meaning; while the insular cortex mediates aspects of speech production and articulatory control.

Together, these regions work as a network whose function is the processing of words and word sequences to determine context and meaning thus enabling our receptive and expressive language abilities.

A study conducted by the Swedish Armed Forces revealed growth in language-related brain areas. Students at the Interpreted Academy underwent MRI scans before and after a three-month period of intensive study. The researchers observed size development in the hippocampus and areas in the cerebral cortex related to language learning.

Impact on Creative Potential

Lexical sophistication, which refers to the expansiveness and overall development of one’s vocabulary, has been used both as a measure for linguistic competency and divergent thinking, since the ability to access a wider range of vocabulary allow for more ideas to be generated including linguistic elements of style such as metaphor and humour.

The relationship between multilingualism and creativity has been the focus of a substantial amount of research over the last forty years. Bilinguals have systematically outperformed monolinguals in tests that measured divergent and convergent thinking as they had a larger linguistic repertoire from which to draw concepts and ideas.

Bilinguals and multilinguals perceive the world differently. They have access to multiple conceptual perspectives that coalesce into a richer subjective experience. Multilingualism stimulates the development of creativity, idea generation, problem-solving and cultural awareness. Multilinguals have access to an expanded conceptual representation, which promotes the integration of contradictory concepts and increases cognitive flexibility. Knowing different languages adds layers of subtle distinctions to the same idea, which is why ambiguity is inherent to multilinguals who, as a result, have access to a wider range of possible solutions to any problem.


Working memory refers to a cognitive structure, formed by several parts of the brain and used as a dedicated, temporary mental workspace for the processing, storage and manipulation of information. One of the components of working memory is the phonological loop which deals with spoken and written material, holds information in a speech-based form and aids with speech production.

Bilinguals outperformed monolinguals in studies that compared them in tasks requiring different levels of working memory. Bilinguals had a faster response rate and were more accurate in response to trials, confirming an advantage in aspects of executive functioning. Monolinguals were also outperformed on tasks unrelated to the language-processing component of working memory: the visuospatial span, which is related to visual and spatial identification. In essence, language acquisition improves all aspects of working memory, even those unrelated to language.

Effects on Nonverbal Intelligence

Nonverbal intelligence refers to cognitive skills and problem-solving abilities in tasks that do not fundamentally require the use of language. Nonverbal cognitive tasks include the conception of abstract ideas, internalised reasoning, the recognition of visual sequences, the comprehension of visual information and the recognition of visual cues in social relations, such as body language.

Maria Viorica, a professor at Northwestern University, pioneered the concept of co-activation during bilingual spoken language comprehension. It refers to the tendency of fluent bilinguals to have both languages active at the same time, consciously or unconsciously, which also activates inhibitory control in the prefrontal cortex. The bilingual brain is constantly exercised as it is forced to choose between two simultaneously co-activated languages. The bilingual brain, as a result, becomes far more adept at performing cognitive tasks.

As bilinguals constantly need to manage attention to the jointly activated languages, they receive far more executive control practice. As a result, they tend to exhibit a processing advantage over monolinguals on non-verbal executive control tasks.

Effects on Verbal Intelligence

Verbal intelligence is the ability to use one or more languages to articulate and express one’s thoughts and feelings, either orally or through writing. It also encompasses comprehension and a variant degree of linguistic empathy. There’s a close correlation between verbal intelligence, problem-solving and abstract reasoning.

A study conducted by Peal & Lambert (1962) examined the effects of bilingualism on intellectual functioning. Bilinguals performed significantly better than monolinguals on both verbal and nonverbal intelligence tests. The intellectual advantage is the result of greater mental flexibility and concept formation ability. Bilinguals have a more diversified set of mental abilities as their structures of intellect differ from monolinguals. Prior to this study, it was widely believed that early childhood bilingualism inhibited cognitive development in children. Bilingualism was thought to be a lamentable condition that must be avoided.

These findings not only make a case for multilingualism, but also have implications on an array of disciplines including linguistics, psychology, neuroscience, education, sociology, economics, and political science. Since language is uniquely human, understanding it might pave the way to understanding a question that has plagued philosophers since antiquity; ‘what is consciousness?’



Image by Shehab Ali. Copyright 2019 Arcana.

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