Born in 1896 in Russia, Lee Vygotsky died of tuberculosis at age 37. Yet his early demise did not prevent him from ranking among the psychologists who have had the greatest influence. His incomplete theory on child psychology held that community and social interaction were fundamental to cognitive development. Vygotsky's ideas contrasted with those of his contemporary Piaget, that children must develop before they can learn.
The first stage of Vygotsky's language development theory, the primitive stage, is characterized by the infant experimenting with sound production. The coos, ga-gas and babbles emitted have no purpose but to explore the baby's sense of sound. The lack of speech during this phase means no verbal thought is taking place. This does not mean the baby has a lack of thought, but rather a lack of relationship with her thoughts.
The naive stage begins when babies learn to speak. The baby speaks words without grasping their purpose and meaning. When an infant utters "doggy," he could mean "Where is my doggy?" or "I want the doggy now." Over time, the child uses slightly more complex phrases such as "doggie now." These phrases lack an understanding of grammar or structure. The infant determines meaning from the responses others give to his phrases.
A child starts to use objects to signify meaning and words in the external stage. Toys and fingers are examples of what she might use to express herself. Rhyming is also a device used in this phase to help solidify her memory of objects and sounds. What Vygotsky calls "egocentric speech" typifies this phase as well. This kind of speech occurs when the child talks to herself while alone and when interacting with others. Vygotsky calls this event the start of a child's verbalization of thought.
The ingrowth stage occurs when children start to internalize many of the tasks he learned during the previous phases. For example, he will count in his head as opposed to using his fingers to numerate. A need to communicate with others people around him improves his ability to internalize thought and actions. Inner speech also shortens during this phase, called predication. Thought sentences will lack a subject, because that subject is already known to the child.