By: Emma Jaeger
You may often hear individuals say that learning a second language as an adult is much harder than it is for a child. Why could that be? Is that statement even true?
For a significant period of time, many scientists believed that there was a so-called critical period during which a person could best learn a language. This Critical Period Hypothesis stipulated that 2nd language acquisition needs to occur between the ages of 2 years and puberty for optimal results, in part due to children’s increased levels of neuroplasticity (2013 Vanhove). Neuroplasticity is the brain’s ability to increase cognitive efficiency through pruning, rewiring, and strengthening various synaptic pathways. The Critical Period Hypothesis has been called into serious question since its introduction in the late 1950’s (2014 Ping), and recent studies have indicated that adult brains can exhibit neuroplasticity as well (2017 Stamps).
That being said, children’s brains are still developing and are therefore somewhat more moldable, or plastic than adult’s brains. While young people have increased neural plasticity, adults still have the ability to remap and rewire their cognitive pathways. This is crucial for patients who have experienced head trauma, strokes and certain types of brain cancers such as Glioblastomas, as this allows them to regain cognitive function and re-assign the crucial processes of damaged pathways to different neural networks (2016 Duffau). Not only does neuroplasticity relate to illness and injury, but education as well.
In a 2014 study, learning a second language was shown to cause anatomical neural changes in children, young adults and the elderly, but was sensitive to age (2014 Ping).
One area of interest when investigating neuroplastic changes is Gray Matter density. A 2004 study contrasting early bilingual learners, late bilingual learners and a monolingual control group, found that both groups of bilingual children showed increased grey matter density concentrated in the left inferior parietal lobule, than their monolingual counterparts. This lobule is a section of the brain associated with auditory, visual and somatosensory processes. They also discovered that the increased grey matter density was greater in the early bilinguals, who learned their second language before the age of 5 years old (2004 Mechelli).
A study published in August of 2020 in the Journal of Brain and Language subsequently supported that learning a second language at an earlier age results in increased speech encoding in the auditory brainstem, holding language exposure levels constant (2020 Giroud). This means that children who had similar levels of exposure to a second language, but began learning at an earlier age demonstrated higher levels of neuroplastic changes in response to the second language.
While there may not be a so-called critical period after which learning a language is impossible, beginning to learn a second language at an earlier age may be increasingly fruitful, as children’s great capacity for neural plasticity allows for neural mapping to be trained to process new languages more efficiently.
A. Mechelli, J.T. Crinion, U. Noppeney, J.P. O'Doherty, J. Ashburner, R.S.Frackowiak, et al. Structural plasticity in the bilingual brain: proficiency in a second language and age at acquisition affect grey-matter density. Nature, 431 (7010) (2004), p. 757
Duffau, Hugues. “Brain Plasticity and Reorganization Before, During, and After Glioma Resection.” Glioblastoma, 2016, pp. 225–236., doi:10.1016/b978-0-323-47660-7.00018-5.
Stamps, Judy A., and V. V. Krishnan. “Age-Dependent Changes in Behavioural Plasticity: Insights from Bayesian Models of Development.” Animal Behaviour, vol. 126, Apr. 2017, pp. 53–67., doi:10.1016/j.anbehav.2017.01.013.
Vanhove, Jan. “The Critical Period Hypothesis in Second Language Acquisition: a Statistical Critique and a Reanalysis.” PloS One, Public Library of Science, 25 July 2013, www.ncbi.nlm.nih.gov/pmc/articles/PMC3723803/.