The main principle of Vygotsky’s Cultural-historical Theory of Psychological Development is that cultural mediators play a role in psychological development. Examples of cultural mediators include words, signs and myths. People do not develop in a vacuum. Psychological development is influenced by the cultural mediators in our lives. As children grow, they learn about the culture into which they are born and raised. Elements of our culture are passed down to us by interaction with people around us. We learn the words, speech patterns, symbols and myths of our culture as we learn everything else.
I would argue that Vygotsky’s theories are still very much relevant today. Every culture is unique, and as children grow they are acculturated by those around them. In modern society, cultural mediators often come through television and other media as well as by interpersonal contact. Every communication a child has teaches him a bit more about the world he is growing up in, and influences his development.