Humans, especially children, have an amazing capability to learn language. Within the first year of life, children will have learned many of the necessary concepts to have functional language, although it will still take years to develop fully. In this concept we will discuss the several theories that discuss the development of language in children, as well as the brain areas important to language development.
Theories of Language Development
B.F. Skinner believed that children learn language through operant conditioning; in other words, children receive "rewards" for using language in a functional manner. For example, a child learns to say the word "drink" when she is thirsty; she receives something to drink, which reinforces her to continue using the word for getting a drink. This follows the four-term contingency that Skinner believed was the basis of language development - motivating operations, discriminative stimuli, response, and reinforcing stimuli. Skinner also suggested children learn language through imitation of others, prompting, and shaping.
Noam Chomsky discussed the biological basis for language and believed that children have innate abilities to learn language. He termed this innate ability the Language Acquisition Device. Chomsky believed children instinctively learn language without any formal instruction. He also believed children have a natural need to use language, and in the absence of formal language, children will develop a system of communication to meet their needs. He observed that all children make the same type of language errors, regardless of the language they are taught. His theory is based on inference, and no genetic basis or brain location has been located demonstrating an innate ability for language.
Jean Piaget's theory of language development suggests that children use both assimilation and accommodation to learn language. Assimilation is the process of changing one's environment to place information into an already existing schema (or idea). Accommodation is the process of changing one's cognitive structure (idea) to adapt to the new environment. Piaget believed children need to first develop mentally before language acquisition could occur. Children first create mental structures within the mind (schemas) and from these schemas, language development occurs.
Lev Vygotsky's theory of language development focused on social learning and the zone of proximal development (ZPD). The ZPD is a level of development obtained when children engage in social interactions with others; it is the distance between a child's potential to learn and the actual learning that takes place. Vygotsky's theory also demonstrated that Piaget underestimated the importance of social interactions in the development of language, and his theory has been used successfully in the field of education.
Language and Cognition
The following timeline overviews the ages at which children generally acquire language:
- 4-6 months - Babbling using all sounds
- 6-9 months - Babbling becomings more focused, narrowing of sounds
- 10-12 months - First words develop
- 18-24 months - Children begin using 2 word phrases (example: "Me up" or "Get milk")
- 2-3 years - Children begin using 3 word phrases in correct order with inflection
- 4-5 years - Children start speaking with nearly complete syntax
- 5-7 years - Children begin using and understanding more complex language
- 9 years and older - Children understand almost all forms of language
Brain Function and Language
Several areas of the brain must function together in order for a person to develop, utilize and understand language (Figure 1). Broca's area, located in the frontal lobe of the brain, is linked to speech production, and recent studies have shown it to also play a significant role in language comprehension. Broca's area works in conjunction with working memory to allow a person to use verbal expression and spoken words.
Wernicke's area, located in the cerebral cortex, is the part of the brain involved in understanding written and spoken language (Figure 2). Damage to this area results in speech that is unable to be understood by others. The primary auditory cortex, located in the temporal lobe and connected to the auditory system, is organized so that it responds to neighboring frequencies in the other cells of the cortex. It is responsible for identifying pitch and loudness of sounds. The angular gyrus, located in the parietal lobe of the brain, is responsible for several language processes, including number processing, spatial recognition and attention.