How does language develop?

We use symbols to communicate with other people and to reflect or exchange our thoughts, feelings, and knowledge. Symbols are a tool when communicating with other people. Using language includes language comprehension and language production. Language comprehension is the understanding of what other people say, write or portray (passive). Language production is speaking, writing or portraying to other people (and is active). Language comprehension leads to language production.

Which components does language have?

Generativity is a concept showing how important communication is. Generativity refers to the idea that through the use of an infinite set of words in our vocabulary, an infinite number of sentences can be formulated, and an infinite number of ideas can be expressed. Language consists of different terms. First, phonemes: the smallest pieces of sound that a language can produce. Then follows a phonological development, which reflects the acquisition of knowledge about sounds of language. Second, morphemes: the smallest pieces of language still having a meaning. Morphemes are composed of one or more phonemes. Here follows a semantic development, which is the knowledge of the meaning of certain expressions in a language. Thirdly, there is syntax: the rules of a language that specify how words of different categories (e.g. verbs, nouns) can be combined. This results in a syntactic development: the knowledge of the rules of a language. Ultimately, there is also a pragmatic development, which means how to learn to use a language.

What are the requirements for a language?

Full use of language is only achieved by humans. Therefore, one of the requirements is the brain. A second requirement is to realize that a language can be learned it must be seen and heard. 

Language is species-specific, because only people can speak a language. And language learning is species-universal, because in general humans are able to learn a language, except people with cognitive impairments. Dogs, parrots and mainly monkeys can also learn to understand our language to a certain extent. Monkeys can be taught to communicate using a lexigram board. The human brain builds a communication system with the complexity, structure and generativity of language. 

For almost everyone, the left hemisphere is dominant in language. The left hemisphere controls and presents language-related stimuli. The critical period for learning a language is between the fifth year of life and puberty. The critical period for language is a period in which language develops easily. After the critical period, it becomes much more difficult to learn a language and it is nearly impossible to learn to speak the language perfectly.     

Not only the brain, but also other people are important in the development of language. Children need to be exposed to language. Already early, babies identify language as something important and prefer listening to language rather than other sounds. The so-called infant-directed speech (IDS) is a special way of talking to babies and small children. Characteristics of IDS are: emotional, exaggerated, slow, clear and accompanied by exaggerated facial expressions. The intonation of words helps small children to interpret the meaning of the word more easily. The brain also reacts more to IDS than to full-language. Yet IDS is not universally used. Some people think that children cannot understand language and so they do not need to talk to them. When children are able to say their first words of their own. Often the parents directly try to ensure that the child learns the language by saying words/ sentences and giving the child instructions to repeat it.

Bilingualism is the ability to use two languages. There is a growing number of bilingual children. Learning can already begin in the womb. Children who grew up bilingual show no confusion between the two languages, they build up two different language systems. Making mistakes is completely normal and does not indicate confusion, rather a knowledge gap that is filled with the other language.  

How does the process of language acquisition work?

How does speech perception develop?

The first step to learn language is the perception of speech. The basis of this process is prosody. The characteristic of languages that make them sound different, like rhythm, tempo, cadence, melody, intonation patterns, etc. Both adults and babies perceive certain speech sounds belonging to a certain category. This is called categorical perception. The voice onset time (VOT) is the time between the moment that air passes through the lips and the moment that the vocal cords begin to vibrate. The VOT determines which letter is spoken. Studies on VOT show that in comparison to adult’s babies have a better ability to differentiate between speech sounds, which helps them learn any language. When children are 1 year old, their perception of speech has already become 'grown-up' and they can no longer distinguish the different speech sounds as good as before.

How does word segmentation develop?

Word segmentation is the process of discovering in fluent speech, where the words begin and end. It starts in the second half of the first year of life. Babies are good at picking up regularities in their mother tongue helping to find word boundaries. In addition, they are sensitive to the distribution characteristics of speech. Explaining the phenomenon that in each language, certain sounds occur more often than other sounds. Another regularity is the return of the own name.    

How to prepare for language production?

After the word segmentation, the second step is the preparation of language production. First, these are uncontrolled sounds, such as crying, shouting, burping, or smacking. Then follow the simple sounds, such as 'oooh' or 'aaah'. This early way of language production is called babbling. The babies get more and more control over it. Then they realize that they get reactions to their sounds and they enter into dialogue with others, usually the parents. Babies also use many non-verbal interactions to communicate, such as pointing to objects or people.

How are the first words formed?

As a third step, the first words develop. However, to really be able to learn words and use them, children must recognize that words have meanings. Therefore, the first step is to focus on the problem of reference. Reference in language and speech is the association between the words and the meaning of them. It is difficult for a parent to determine the first word of a child. In the first period, children only use one word at a time to make something clear. This is called the holophrastic period. It can sometimes cause problems. It can lead to something called overextension. This is a form of generalization, for example a child can call every four-legged animal a dog.   

Children learn the meaning of words mainly from the parents, by IDS, but also when parents, for example, emphasize new words. The child is active enough to learn the meaning of words. They do it through fast mapping: a process in which a new word is learned quickly by hearing the contrastive use of a familiar word and the unfamiliar word. Words are also learned through pragmatic cues, which are aspects of the social context. Another tool is syntactic bootstrapping: a strategy to use grammatical structures of whole sentences to learn the meaning. 

Differences in the number of words children know can have different reasons. The number of words a child knows is related to the number of words they hear. One of the main determinants for this is the SES of the parents. The higher the social class of the family, the more words a child knows. It also predicts the amount of words a child will learn in the future. The quality of the spoken language is also important. The physical environment is of importance here. In noisy environments, a child will learn new words less easily. In order to reduce differences between children, interventions can be applied. Such as reading more books and increasing the time that parents talk to their child.

There are concerns about the use of technology in children under the age of 2. It reduces the time that children are actively involved with the best sources of learning, namely caregivers and objects. It appears that children can learn from active communication via live video interactions. But the so-called 'educational values' of certain games or programs must be always looked at with a skeptical view.  

How are words combined?

In the fourth step, the words are put together into complete sentences. Children start with composing words to kind of telegram style sentences. They use two or a few more words. Each language has a certain set of rules and exceptions that determine how elements of language can be combined. This is the grammar. Children learn it by generalizing what they have heard before. Evidence for it is overregularization: speaking errors in which children treat irregular forms of words as if they were regular (breaked-broked).   

How do conversational skills develop?

Finally, the conversation capacities are developed. This starts with collective monologues. Collective monologues are conversations between children who have nothing to talk to each other. They do not react to what the other person said, and only talk about themselves. Still they do talk to each other. Later they start talking through narratives: descriptions of past events that have the basic structure of a story. The development of perspective in a conversation is related to the executive functioning of a child. The more control they show about their own perspective, the easier they can take the perspective of someone else. At the age of about 5 to 6 years the basic language elements are present.

Which are the theoretical problems in language development? 

There is evidence for both nature (the brain) and nurture (experience with language) in the process of language development.  

How was is the nativists view on language development?

Chomsky countered Skinner's theory that language is learned through punishment and reward processes. Chomsky stated that it is not possible because we are able to understand and produce sentences that we have never heard before. The explanation for it is that we have innate knowledge of language structures that was not taught. According to Chomsky, people are born with Universal Grammar: a set of abstract and unconscious rules known in all languages. 

Which are the ongoing debates about language development?

Current theories acknowledge part of Chomsky's observations. The question, however, is to what extent explanations could be found in the genes or in the environment. And to what extent the child contributes: did the cognitive and neural mechanisms that underlie language learning only evolve to support language learning (domain-specific) or are they used for learning all kinds of things (domain-general). Children are motivated to interact with others and hereby gradually discover regularities in language. On the other hand, it can also partly be explained according to Skinner's principles, for example, parents laugh in response to the babbling of the child (positive reinforcement). Concerning the second question, nativists argue that the brains of children contain an innate language model that is different from all other aspects of cognitive functioning. This is called the modularity hypothesis. An alternative view suggests that there are general mechanism underlying underlying language learning. For example, the ability to select small pieces of information is also useful in other domains. Additionally, language development disorders not only language aspects are affected, but also aspects of more general cognitive functioning. Connectionists handle kind of information processing that emphasizes the equal activity of a number of pieces that are connected to each other. They mainly believe in the general language mechanisms, in contrast to the other two types of theoreticians who believe in language-specific mechanisms.

Gesturing is something that often goes together with speaking. Gesturing starts early. The more gestures children make at an early age, the greater their vocabulary will be when they are older. Deaf children can develop their own sign language. In a school in Nicaragua where the children and teachers did not know the sign language, their own sign language was soon developed. Children who later attended school quickly learned this language, which slowly changed into a complete, complex language with its own grammar.

The most important individual differences fall under the category of language development disorders. Many disorders are only discovered when a child goes to school. Approximately 7% of school-age children in the US are diagnosed with specific language impairment (SLI). These children have difficulty with language-related tasks. Children with genetically inherited developmental disorders are often lagging behind on various aspects of language development. The language skills of children with autism spectrum disorder, are an indication for outcomes later in life. Deaf children can also develop language disorders if they do not early learn sign language. These children can also receive a cochlear implant that stimulates the auditory nerve.  

How does the use of non-verbal symbols work in the development?

To use symbols in non-verbal language, dual representation is required. This is an idea that symbolic artifacts must be mentally presented in two different ways similarly: both in a realistic way and in a symbolic way. As children grow older, they learn to understand symbols better and better. For example, a child going to school understands that a red line on a map does not mean that the road is red in real life, whereas younger children think so. Drawing is also a symbolic way of non-verbal language. The first drawings of children have no specific purpose. When children are 3 to 4 years old, they try to draw something specific, like a person.