In sociology, interactionism is a theoretical perspective that derives social processes (such as conflict, cooperation, identity formation) from human interaction. It is the study of how individuals act within society. Interactionist theory has grown in the latter half of the twentieth century and has become one of the dominant sociological perspectives in the world today. George Herbert Mead, as an advocate of pragmatism and the subjectivity of social reality is considered a leader in the development of interactionism.  Herbert Blumer expanded on Mead's work and coined the term "symbolic interactionism".