What is language?
Language is a code where meaning is turned into symbols. These symbols might be words (in spoken or written languages), signs (in visual sign languages) or symbols (in visual and computerised language systems).
Signs and symbols are not unique to human beings. However, humans use a highly sophisticated language system which is capable of an infinite variety from a finite set of rules. Grammar, the rules of a particular language, allow humans to say new sentences never said before, and yet still easily understood by a wide range of people who share that particular language.
What is child language acquisition?
Children are not born able to speak a language. However, they go on to learn the language or languages of their parents, peers and others (such as their teachers and classmates) in a remarkably short period of time. Most children aged 6-7 years old can understand and use a huge variety of words, concepts and grammatical structures in which to express their needs, emotions and thoughts.
The remarkable thing is not that children find the task of acquiring a language difficult, but that most children acquire languages seemingly effortlessly.
How do children acquire language (learn to understand, talk and use language)?
There are many linguistic theories on this topic, and the debt on how children learn to talk has challenged some of the finest academic minds. The honest answer is that we still don't know exactly how children learn language. However, there has been a huge scientific interest in this topic and there are thousands of research papers, academic texts and popular books on the subject; not forgetting television programmes and web resources.
Children appear to have biological (inherited abilities), social (the desire to communicate with others) and cognitive (the ability to employ huge thinking resources) skills which facilitate language learning. They are also typically raised in an environment where they are exposed to language(s) and so hear a huge amount of language data.
'...imitative skills, a general language-learning-mechanism, cognitive awareness, and structured input all play their part in guiding the course of language acquisition'
David Crystal, 1998: 237
What is language impairment?
Language impairment, also known as language disorder, is when a child experiences difficulties acquiring and using the language or languages employed by their community.
This may be caused by a number of factors which interfere with the normal process of language acquisition.
Lack of language input may be caused by sensory impairments. For example, deafness or partial hearing loss reduces the amount of speech and language information reaching the child. Many countries including the UK now have routine newborn hearing assessment to identify children with congenital deafness. Audiology services review children's hearing to identify other types of hearing loss which may occur, including otitis media (glue ear).
Lack of language input may also be caused by environmental deprivation. Children living in poverty may receive a poor diet, affecting their general development, including language acquisition. Parents living in poverty may have had fewer opportunities themselves during their childhood and therefore be less well equipped to provide their child with rich play and learning experiences. The US and UK recognised that children need play opportunities in which to learn language and other important skills. This lead to the Head Start and Sure Start initiatives respectively.
Some children have learning difficulties caused by a genetic disorder, syndrome or other disability. Any general learning difficulty will mean that the child has fewer cognitive resources to process the language they hear. This may lead to slower and/or incomplete language acquisition.
Humans are social animals. Our ability to communicate and cooperate has led to a highly successful increase in population. Children live longer and more children survive into adulthood than in previous centuries. Social communication is therefore an evolutionary advantage. In today's world, communication skills are also excellent skills to enhance employment opportunities.
Some children may fail to understand how to use language. These children may lack the ability to understand the motives of others and how to use language to request, negotiate and express their needs, emotions and ideas. Social communication difficulties range from very minor to the very severe.
Crystal, D., 1998. The Cambridge Encyclopedia of Language, Second Edition. Cambridge: Cambridge University Press.