Final answer:
Lev Vygotsky developed the socio-cultural theory, emphasizing the influence of cultural and social interactions on individual development.
Step-by-step explanation:
The socio-cultural theory of development was developed by Russian psychologist Lev Vygotsky. He believed that an individual's development was deeply connected to their cultural background, asserting that the social world influences the formation of language and thought. Vygotsky highlighted that the historical and cultural context plays a crucial part in one's development. His work has been fundamental in understanding how human development is intertwined with the social environment and cultural norms. He proposed that human development is rooted in one's culture, where a child's social world forms the basis for the formation of language and thought. Vygotsky also considered historical influences to be key in one's development.