Like Erik Erikson, this psychologist saw childhood as divided into periods separated by crises, though this psychologist used age rather than ideas as a basis. That idea, found in his The Problem of Age, succeeded another which described consciousness as based on reflex. In a more well-known theory, this psychologist described how children merely think out loud, while adults utilize an extremely complex mental speech in his discussion of what he 
Like Erik Erikson, this psychologist saw childhood as divided into periods separated by crises, though this psychologist used age rather than ideas as a basis. That idea, found in his The Problem of Age, succeeded another which described consciousness as based on reflex. In a more well-known theory, this psychologist described how children merely think out loud, while adults utilize an extremely complex mental speech in his discussion of what he termed internal language. This psychologist also developed a model which assists the development of childhood skill by giving tasks that are within the zone of proximal development. For 10 points, name this author of Thought and Language, a Russian psychologist.
Like Erik Erikson, this psychologist saw childhood as divided into periods separated by crises, though this psychologist used age rather than ideas as a basis.
Lev Vygotsky