According to B.F. Skinner language is a result of learning through reinforcement and imitation. He said that language is shaped through reinforcement. Parents selectively criticize incorrect speech and reinforce correct speech through praise, approval, and attention. This causes the child's utterances to be progressively shaped in the direction of grammatically correct speech. Others believe that children acquire vocabulary and sentence construction mainly through imitation.
Some problems with the learning theory being the sole explanation for langauge acquisition exist. Imitation cannot account for patterns of speech such as telegraphic speech or for systematic errors such as overrergulation. These are not heard in normal everyday speech. Also, there are problems with reinforcement. Parents seems to reward children more for the content of the utterance than for the correctness of the grammer. Parents are much more likely to correct a child for making a untrue statement than making a grammatical error.