For Mead and Vygotsky, human persons develop with the use of language acquisition and interaction with others. The way that we process information is normally a form of an internal dialogue in our head.
A cognitive and emotional development of a child is always a mimicry of how it is done in the social world, in the externalreality where he is in.
Both Mead and Vygotsky treat the human mind as something that is made, constituted through language as experienced in the external world and as encountered in dialogues with others.