Thought comes before language or thought and language are interdependent processes?
Regarding the role of language for development and the relationship between language and thought: According to Piaget, thought comes before language, which is only one of its forms of expression. The formation of thought basically depends on the coordination of sensory motor schemes and not of language. This can occur only after the child has reached a certain level of mental abilities, subordinating herself, to the thought processes. The language allows the child to evoke an object or event absent at the communication of concepts. Piaget, however, established a clear separation between the information that can be passed through language and processes that do not seem to suffer any influence of it. This is the case of cognitive operations that can not be worked by means of specific training done with the aid of language. For example, you can not teach, just using words, to classify, to serialize, to think with reversibility. As for Vygotsky, thought and language are interdependent processes, from the beginning of life. The acquisition of language by the child modifies its higher mental functions: it gives a definite shape to thought, enables the emergence of imagination, the memory usage and the action planning. In this sense, language, unlike what Piaget postulates, systematizes the direct experience of children and therefore acquires a central role in cognitive development, reorganizing processes that are ongoing.