Language Acquisition Device

In 1965 the linguist Noam Chomsky put forward the idea that language was innate, and suggested that childrens language acquisition was supported by a Language Acquisition Device (LAD). Other linguists and psychologists, however, have their own theories of child language acquisition, three of which base the development of language on interaction with caregivers, on cognitive development, and on imitation and reinforcement respectively. At first glance, it seems that the different theories of child language acquisition contradict each other, that it would be impossible for all five theories to have an element of truth in them. When, however, you look at the theories in more detail, you realise that the way in which children acquire language is likely to be a result of the five different theories working together. By describing language as innate, Chomsky was suggesting that children are born with an internal knowledge of language, that the rules of language are inside their brains from birth, so that when they begin to speak, they will have a pre-existing knowledge of grammatical rules. This essay will demonstrate that while Chomsky’s LAD is undoubtedly present in children, the other theories of child language acquisition also play a role in the development of children’s language; none can be disregarded as being untrue.

In 1986, Chomsky added to his theory of language innateness by putting forward the idea that the Language Acquisition Device contained a Universal Grammar, a set of basic rules of grammar that characterise all languages. This explains the fact that children from all over the world pass through similar stages, at similar ages, in the acquisition of language, despite vast cultural differences. By 5 years of age, most children have a good grasp of the basic rules of their own language. This provides strong evidence for the existence of a LAD, as if language were not innate, children from different countries and backgrounds would surely pick up different aspects of language in different orders, and all children, even those from the same backgrounds, would acquire language at different rates.

Further evidence for the existence of a Language Acquisition Device comes from what was termed s-structures (surface structures) and d-structures (deep structures) (Chomsky, 1957, 1982). Different languages have different surface structures (the actual phrases used in a sentence), but they all share the same deep structures, reflecting the sentence’s meaning. The fact that children understand deep structures without having to be actively taught about them suggests that language is innate: children have an inborn understanding of grammatical concepts, understanding that the order of words within a sentence is important.

The grammatical errors that children make during the process of acquiring language, known as overgeneralisation, also suggest that language is an innate module, thereby providing evidence for the existence of a Language Acquisition Device. Overgeneralisation occurs, for example, when children apply the past tense -ed inflection to irregular verbs such as ‘go’. Children obviously wouldn’t hear an adult saying ‘goed’, which suggests that children have an inbuilt knowledge of grammatical rules: they know that to form the past tense they have to use the -ed suffix, but they aren’t yet aware of irregular verbs. Evidence for grammatical overgeneralisation by children comes from an experiment carried out by Brown and Bellugi in 1964, in which the early speech of two children was analysed. The -ed past tense inflection was used for irregular verbs such as ‘come’ (‘comed’) and ‘grow’ (‘growed’). Further overgeneralisation occurred when forming plurals: nouns such as ‘sheep’ and ‘tooth’ were made plural by adding the -s inflection (‘sheeps’ and ‘tooths’). Again, the two children had learnt that to make a noun plural you used the -s inflection, but they were not yet aware of nouns which didn’t follow the normal grammatical rule.

The fact that not all children are exposed to Child Directed Speech provides further evidence for the innate nature of language. The cultures of the islands which lie in the South Pacific Ocean, for example, believe that such ways of speaking actually interfere with a child’s language development. Infants in countries such as Samoa and Papua New Guinea, therefore, do not hear modified forms of language: all they hear is their native language in all its complexity. Despite the fact that the only language they are exposed to is the standard, unaltered form of their native language, infants in such countries pick up language at much the same rate and just as quickly as infants who are exposed to simplified forms of language, who are exposed to Child Directed Speech. This points clearly to the fact that language is innate, as if it wasn’t, children in such countries would arguably acquire language at a later age, as a result of them not being exposed to simplified forms of language.

A final piece of evidence for the existence of a Language Acquisition Device is the fact that language is specific only to humans. No other species spontaneously develops language in the way that humans do. This fact, coupled with the relative speed and ease with which children acquire their first language, provides substantial evidence for the existence of a LAD, especially as language is far too complex to be taught completely from scratch.

Despite all of this evidence supporting the existence of a Language Acquisition Device, there are some factors which would throw the existence of the LAD into doubt. One such factor is the fact that feral children, along with children who have suffered extreme cases of abuse and neglect fail to master language, beyond the basics, even when taught by specialists. One such case is that of Genie (Curtiss, 1977). Up to the age of 13, from the age of approximately 20 months, Genie was kept in an isolated room with practically no human contact. Upon being rescued, Genie successfully learnt vocabulary, although she failed to understand the rules behind grammar, and as a result was only able to master three-word utterances as a result of the lack of attention and interaction she received throughout her infancy and childhood. This situation has been found to be the case with feral children, and with other victims of extreme child abuse. The inability to master grammatical rules, and therefore to speak in grammatically correct and complete sentences, can be explained by the Critical Period Hypothesis (Lenneberg, 1967), which theorises that language learning is easiest before a certain age. Combining the fact that feral children and abused children fail to master anything but the basics of language with the Critical Period Hypothesis provides evidence against the existence of a LAD. If language were innate, as Chomsky suggested, such children would be able to acquire language, however old they were when rescued, as it would simply be a matter of learning the vocabulary; they would have the grammatical rules already in place. The fact that they are unable to suggests that something else is required: this is where the other theorists of child language acquisition come in.

One such alternative theory of children’s acquisition of language is the Behaviourist Account, associated with the psychologist B.F. Skinner. Skinner, 1957, suggested that children acquire language through a process known as operant conditioning. In a linguistic sense, this means that when a child uses language correctly, in terms of both the lexis and the grammar, they are rewarded in various ways. Due to these rewards, children are motivated to repeat the behaviour, thereby shaping their language and ensuring that it develops successfully.

Another theory which goes against that set out by Chomsky is the Cognition Theory. Jean Piaget, a developmental psychologist, believed that cognitive development (the development of mental abilities and skills) was the overriding influence on the development of language, with language being neither innate nor learned passively. Piaget’s theory focuses on the precursors of early language, such as gestures and facial expressions, as Piaget claimed that in the first two years of life, the child’s intellectual skills rely on sensori-motor experiences such as seeing, hearing and touching, as opposed to on words and images. While Piaget agreed with Chomsky in the sense that children develop a set of rules, he believed that rather than being innate, they came instead from a wider cognitive system, whereby children form schemas to help explain events in their lives, and then they are able to talk about them. Piaget’s concept of Object Permanence helps to support his cognition theory, in turn providing evidence against the existence of a Language Acquisition Device. Before 18 months of age, infants are egocentric, as they can’t mentally process the concept that something can exist outside of their immediate surroundings. By the time they are 18 months old, however, they have developed a sense of object permanence, realising that objects exist all of the time, even when the infant can’t see them. The development of object permanence coincides with a substantial increase in vocabulary: if, as Chomsky suggested, language was innate and children possessed a LAD, object permanence wouldn’t take such a long time to develop, as they would have a sufficient level of development to understand that an object couldn’t and wouldn’t just disappear.

A further theory which helps to question the existence of Chomsky’s Language Acquisition Device is that of the psychologist Jerome Bruner. Bruner’s interactionist theory stresses the role of linguistic interaction from caregivers in a child’s language development. This theory doesn’t completely disprove the existence of the LAD; rather it suggests that something else is needed. Bruner suggested that children have a Language Acquisition Support System (LASS), whereby caregivers support their child’s acquisition of language in social situations.

A final theory which provides evidence against the existence of the Language Acquisition Device is that put forward by the psychologist Lev Vygotsky: the Socio-Cultural theory. The main tenet of this theory is that both social interaction and experiencing different social and cultural contexts are important for the development of language. Two significant factors which contribute to language development were identified: Private Speech (when a child talks aloud to itself, providing evidence that they are thinking for themselves) and the Zone of Proximal Development (ZPD) which occurs when a child needs the help of a caregiver in order to interact. The caregiver will either respond for the child, or will try to encourage a response from the child, both of which provide the child with a model to apply to similar situations in the future.

This essay has discussed both evidence for and against the existence of Language Acquisition Device as proposed by Chomsky. The existence of the LAD has been challenged not only by other theories of child language acquisition but also by individual cases of feral and abused children. As the evidence set out in the essay suggests, the existence of Chomsky’s LAD cannot be disproved completely, as arguing that it didn’t exist would put too many things down to coincidence, examples being that children the world over pass through similar stages of language development, and that children instinctively apply grammatical rules to irregular verbs and nouns, leading to overgeneralisation. You can’t, however, simply disregard the work of other psychologist and linguists, as they all carried out their research to prove their hypotheses. Therefore, it is likely that all five of the theories mentioned play a part in children’s acquisition of language: while language may be innate, it develops alongside a child’s cognitive development and children require input and encouragement from their caregivers in order for their use of language to develop fully. To conclude, no one theory of child language acquisition can be said to be wholly responsible for children’s acquisition of language, it is different aspects of each theory working together which make language learning such an impressive feat; this neither proves nor disproves the existence of Chomsky’s LAD.