By studying child language development, linguist are able to achieve a greater understanding language as a whole. Language is a complex phenomenon exclusive to humans, and we are yet to fully understand all of its aspects. We continue to learn more and more every day. By being able to study children acquiring language, we are able to learn more about how it functions.
In an experiment, using the target word pretty, it was discovered that at 18 months a child could perfectly say the word, then at 24 months, the same child would say the same word differently, and then again at 36 months be able to say it correctly. We have learned that child language development takes place in a U shaped curve. That is that when a child is first beginning to speak the are mimicking what they hear. So if they hear the word pretty(/prIti/) , they are able to mimic the word. But at the 24 month mark, they no longer pronounce the word as pretty (/prIti/) but rather as bitty( / bIdi/). If the child was able to properly pronounce the word, then why is it that he would no loner be able to? To understand what is happening must look at Skinner's theory of language.
Skinner believes that language is innate, something that we are born with. That we simply do not memorize words as Noam Chomsky believes, but rather apply a set of rules known as Universal grammar. It takes us some time to develop all the rules that make up this phonological backbone that allows us to communicate.
At t24 months the child is no longer just mimicking what they here but they are in the development stage, but has yet to fully develop all the rules required to properly say the word. At 18 month stage, the child is in the per-representational stage. They do not hear phonemes or syllables, they just see the word as a single sound. At the 24 month stage, the child is in the representational stage where they beging to see the phonemes and syllables within the word, and rather than pretty (prIti/)...