Although neither of these two sets of studies have any direct or obvious connection with the problems that children face in growing up, they do shed a little light on the way their thinking develops. As more of such studies are undertaken, we will gain a better understanding of what steps we can take to facilitate the learning of problem-solving skills, both for children in normal circumstances and for those who are socially and economically deprived.
The attainment of the ability to use language in speech enables the child to take his place as a member of society and provides him with a rich source of symbols, which aid him in both verbal and nonverbal learning. Verbal skills may not be essential for cognitive functioning, however, for people deaf from birth onward reach normal levels of cognitive ability without an equal degree of competence in language. Children are also able to perform tasks involving elements for which they have no words in their vocabularies.
There are several contrasting views as to how language is acquired. In opposition to environmentalist theories, Chomsky maintains that language learning results from an innate capacity--a language acquisition mechanism--which enables children to process linguistic data and to generate an infinite variety of original but understandable statements. The fact that children all over the world tend to employ the same strategies and go through much the same stages in learning to talk seems to support Chomsky's nativistic theories.
Luria has theorized that children's verbal development is coordinated with their motor development, but research suggests that the process may be more complicated. Imitation of adults seems to be involved in the learning of language, but parents seem to be more concerned with the truth or validity of small children's utterances and less interested in their grammatical structure. A study in which adults restructured children's statements in more complex ways showed that two-year-olds can be led fairly easily to introduce complex forms into the language they use. Braine has proposed that children learn key (or pivot-class) words, which can be linked with a variety of other (or open-class) words to make sentences. Children apparently introduce structure into their language in much the same way that they structure their environment. Some psycholinguists object to grammatical or structural explanations of language learning because such explanations ignore the semantics of language--what children are actually trying to communicate.
An early study by Smith showed that children's vocabularies grow very rapidly at first, but that the rate slows down by the age of four. Smith's data regarding the rate of growth seem accurate, but she