Final answer:
Lev Vygotsky is the theorist known for developing the sociocultural theory, which states that individual development is molded by cultural and historical factors through language and social interaction.
Step-by-step explanation:
The theorist known for the development of the sociocultural theory is Lev Vygotsky, a Russian psychologist. His theory emphasized that human development is deeply embedded in and influenced by one's cultural background. Vygotsky highlighted the integral role of social interaction and language in the shaping of thought processes and the acquiring of knowledge, insisting that these are central to understanding the development of children and the historical influences on this development. Additionally, Charles Cooley and George Herbert Mead also made significant contributions in sociological perspectives on self-development, while the classical sociologists such as Karl Marx, Max Weber, and Émile Durkheim helped establish the foundational theories in sociology.