How the Brain Acquires Language
Learning Spoken Language
Although early language learning begins in the home, schools are largely responsible for enhancing the spoken language of children and teaching them to read. How quickly and successfully the brain learns to read is greatly influenced by the spoken language competence the child has developed. Therefore, it is important to understand what cognitive neuroscience has revealed about how the brain acquires and processes spoken words. Figure 5.5 presents a general timeline for spoken language development during the first three years of growth. The chart is a rough approximation. Obviously, some children will progress faster or slower than the chart indicates. Nonetheless, it is a useful guide for parents and teachers to show the progression of skills acquired during the process of learning language (National Institute on Deafness and Other Communication Disorders, 2010).
Learning Sounds Called Phonemes
The neurons in a baby’s brain are capable of responding to the sounds of all the languages on this planet. At birth (some say even before birth) babies respond first to the prosody—the rhythm, cadence, and pitch—of their mother’s voice, not the words. Spoken language consists of minimal units of sound, called phonemes, which combine to form syllables. For example, in English, the consonant sound /t/ and the vowel sound /o/ are both phonemes that combine to form the syllable to- as in tomato. Different languages have different numbers of phonemes. It can be as few as 15 in some languages to well over 40 in English. The total number of phonemes in all the world’s languages is more than 200, which represents the maximum number of sounds that the human voice apparatus can create (Sweeney, 2009).
Although the infant’s brain can perceive the entire range of phonemes, only those that are repeated get attention, as the neurons reacting to the unique sound patterns are continually stimulated and reinforced. By the age of 10 to 12 months, the toddler’s brain has begun to distinguish and remember phonemes of the native language and to ignore foreign sounds. For example, one study showed that at the age of 6 months, American and Japanese babies are equally good at discriminating between the /l/ and /r/ sounds, even though Japanese has no /l/ sound. However, by age 10 months, Japanese babies have a tougher time making the distinction, while American babies have become much better at it. During this and subsequent periods of growth, the ability to distinguish native sounds improves, while one’s ability to distinguish nonnative speech sounds diminishes (Cheour et al., 1998).
From Phonemes to Words
The next step for the brain is to detect words from the stream of sounds it is processing. This is not an easy task because people don’t pause between words when speaking. Yet the brain has to recognize differences between, say, green house and greenhouse. Remarkably, babies begin to distinguish word boundaries by the age of 8 months even though they don’t know what the words mean (Singh, 2008; Yeung & Werker, 2009). Before they reach the age of 12 months, many babies can learn words in one context and understand them in another (G. Schafer, 2005). They begin to acquire new vocabulary words at the rate of about 8 to 10 a day. At the same time, memory and Wernicke’s area are becoming fully functional, so the child can now attach meaning to words. Of course, learning words is one skill; putting them together to make sense is another, more complex skill.
In the 1950s, MIT linguist Noam Chomsky argued that all languages contain some common rules that dictate how sentences are constructed, and that the brain has preprogrammed circuits that respond to these rules. Modern linguists think that the brain may not be responding so much to basic language rules as to statistical regularities heard in the flow of the native tongue. They soon discern that some words describe objects while others describe actions. Toddlers detect patterns of word order—person, action, object—so they can soon say, “I want cookie.” Other grammar features emerge, such as tense, and by the age of 3 years, over 90 percent of sentences uttered are grammatically correct. Errors are seldom random, but usually result from following perceived rules of grammar. If “I batted the ball” makes sense, why shouldn’t “I holded the bat” also make sense? Regrettably, the toddler has yet to learn that nearly 200 of the most commonly used verbs in English are irregularly conjugated (Pinker, 1994).
During the following years, practice in speaking and adult correction help the child decode some of the mysteries of grammar’s irregularities, and a sophisticated language system emerges from what once was babble. No one knows how much grammar a child learns just by listening or how much is prewired. What is certain is that the more children are exposed to spoken language in the early years, the more quickly they can discriminate between phonemes and recognize word boundaries.
Just letting the toddler sit in front of a television does not seem to accomplish this goal, probably because the child’s brain needs live human interaction to attach meaning to the words. Moreover, television talk is not the slow, expressive speech that parents use with their infants, which infants like and want to hear. Although toddlers may be attracted to the rapidly changing sounds and images on a television, little or no language development is in progress. There is further evidence that prolonged television watching can impair the growth of young brains. A longitudinal study indicated that the more television toddlers had watched before the age of 3 years, the lower their scores on later tests of reading achievement and number manipulation (Zimmerman & Christakis, 2005).
Most toddlers begin to speak words around the age of 10 to 12 months. In some children, there is a delay, and they may not speak coherent words and phrases until nearly 2 years of age. There is considerable research evidence that this language delay to two years is inherited, and thus represents a distinct disorder not easily remedied by environmental interventions. This revelation diminishes the claim some people make that mainly environmental influences cause language delay (Newbury & Monaco, 2010).
Given the evidence that the brain’s ability to acquire spoken language is at its peak in the early years, parents should create a rich environment that includes lots of communication activities, such as talking, singing, and reading. In schools, it means addressing any language-learning problems quickly to take advantage of the brain’s ability to rewire improper connections during this important period of growth. It also means that parents and teachers should not assume that children with language-learning problems are going to be limited in cognitive thought processes as well.
Cheour, M., Ceponiene, R., Lehtokoski, A., Luuk, A., Allik, J., Alho, K., & Näätänen, R. (1998). Development of language-specific phoneme representations in the infant brain. Nature Neuroscience, 1, 351–353.
Newbury, D. F., & Monaco, A. P. (2010). Genetic advances in the study of speech and language disorders. Neuron, 68, 309–320.
Pinker, S. (1994). The language instinct: How the mind creates language. New York: Harper Perennial.
Schafer, G. (2005). Infants can learn decontextualized words before their first birthday. Child Development, 76, 87–96.
Singh, L. (2008). Influences of high and low variability on infant word recognition. Cognition, 106, 833–870.
Sweeney, M. S. (2009). Brain: The complete mind. Washington, DC: National Geographic.
Yeung, H. H., & Werker, J. F. (2009, November). Learning words’ sounds before learning how words sound: 9-month-olds use distinct objects as cues to categorize speech information. Cognition, 113, 234–243.
Zimmerman, F. J., & Christakis, D. A. (2005). Children’s television viewing and cognitive outcomes: A longitudinal analysis of national data. Archives of Pediatrics and Adolescent Medicine, 159, 619–625.