Social and socio-
Ontogeny and symbolism
Spoken language and sign language
'Language' has been defined in three ways: by listing its 'design features'; its structural properties, particularly its 'rule-governed creativity'; and its uses or functions.
In terms of design features, spoken and signed languages differ trivially in terms of the latter's not using the vocal-auditory channel; but have been claimed to differ more significantly in the extent to which spoken language is composed of arbitrary signs, while sign languages are based on more iconic signs. This has led to an erroneous demotion of the status of sign languages. A more careful analysis shows that both types of language are comparable on this dimension in their contemporary forms, although there is some evidence that languages of both media have become more arbitrary over time. Similarly, structural analyses of both systems reveal they show a similar degree of 'duality of patterning', both below the structure of the word or sign, and above it at the level of grammar.
Children go through very similar stages in acquiring either system when it is the 'natural' language of their early environment, although at different rates. Initially sign language is learned earlier; but later this advantage diminishes. However, most deaf children learn sign language under unusual conditions, since most (c.90 per cent) do not have native signing parents. Such children are comparable to those 'learning' spoken creoles on the basis of pidgin inputs: features of their signing system are creations of the 'learners' themselves. This provides some support for Chomsky's contention that language acquisition is not heavily dependent on the nature of the linguistic input.
Creoles are languages which have developed out of pidgins into
native languages. Structural similarities between spoken
creoles and sign languages may reflect language universals.
This has been claimed as supporting the existence of an innate
language faculty that strongly constrains the properties of
individual languages. An alternative argument is that
language structure is more constrained by functional demands,
structural characteristics resulting as compromises between
the need for a usable language to be clear, cognitively
processable, 'quick and easy', and expressive. These two
theories may well complement each other: the initial stages of
language (both developmentally and historically) might be
accounted for in terms of what is biologically given, whereas
later language may change more in response to its expanding