Lexical density is a useful measure of the difference between texts (for example, between a person’s written language and their speech). To calculate this we must distinguish between lexical words and function words. The lexical density of two real world examples is calculated and interpreted. Lexical density is shown to be a useful measure of how much information is contained within a text.
Noam Chomsky argues that language is innate. Indeed, language acquisition appears to be a genetically initiated and genetically guided process. This argument has been strengthened by the discovery of a gene called FOXP2 that is implicated in the communication disorder known as Specific Language Impairment (SLI).
Linguistic ability is the ability to manipulate symbols, specifically the arbitrary symbols that we call words, in order to create meaning. The developing child does not, of course, acquire this ability all at once. The process of language development may be considered as a series of alternating periods of rapid growth accompanied by periods of calm or consolidation. There are several stages, each incorporating different behaviors, which may be seen as precursors to the acquisition of full linguistic ability. These stages are typically divided into two categories: (1) pre-linguistic, and (2) linguistic.
Typically-developing children follow a chronological sequence of maturation: their development advancing developmental milestones. Language delay is the failure to develop language capabilities at the expected time. There may be receptive language delay or expressive language delay, or these may co-occur. Milestones such as mean length of utterance (MLU), intelligibility, language comprehension, receptive and expressive vocabulary and development of morphology can be used to judge language development. This article also cites a number of causes of language delay.
One of the most interesting questions is, ‘How do humans acquire language skills?’ As with attempts to define language, there is no unanimously accepted explanation of language acquisition. However, in order to provide an oversight, we consider five theories: probability, imitation, cognition, social interaction, and innate ability.
Language is highly complex but can be defined in terms of a number of key properties. Eight such properties are considered: arbitrariness, duality, systematicity, structure-dependence, productivity, displacement, specialisation, and cultural transmission.
An innate ability for language acquisition is the claim that humans are genetically pre-programmed to learn language. Observations such as the uniqueness of the human speech organs, the speed of acquisition of language, the presence of linguistic universals, and the claim that language is unique to humans are all used to support this view.
Children use different semantic functions to express ideas. This is evident in single word utterances known holophrases. A holophrase is a single word – used by infants up to the age of 2;00 years – which has the force of a whole phrase which would typically be made up of several (adult) words. Beyond the so-called One Word Stage, children relate different semantic categories to create meaningful, longer utterances.