Summarise and compare the stages of development according to these theorists: Bowlby, Ainsworth, Vygotsky, Piaget, Freud and Erikson.
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Vygotsky contended that speech and thought were separate systems and each could manifest independently in children thus only the interaction of the two systems resulted in intellectual maturation. His stages of development begin at birth at which time, he argues, humans have the necessary tools for intellectual development.