Interactionism is the theory that symbols, meanings, social structures and the self, are all created and adapt through the interactions individuals have in society. Through actions, and reactions, a certain mutual adaptation is able to occur. It is because of this process that an individual is just a capable as changing a society as a society is of changing an individual.
An Interactionist studies these relationships, and gathers qualitative informations regarding these communications between individuals. With a greater knowledge of how individuals react to certain situations and stimuli, we are able to then design smarter to control what actions we want the consumer to make.
Theories related to Interactionsim include Neo-Marxism, and Pluralism. Pluralism specifically deals with the notion that “the public gets what the public wants“₁
₁ http://en.wikipedia.org/wiki/Interactionism