In the early years, psychology was a very individualistic field. It started out studying what happened within an individual, instead of looking at how they reacted to other people. In the 1930’s, however, social psychology came into being. This is where psychologists looked at how interactions with other people affected the thought patterns and behaviors of individuals.
From early studies of the impact of the presence of others on individual behavior, through to Kurt Lewin’s pioneering work on the behavior of small groups, social Psychology has spread into areas such as conformity, obedience, antisocial behavior, attitudes, and persuasion, as well as interpersonal relationships. The psychology behind these topics has also been applied to thinking in other fields, including organizational theory, marketing, business, and advertising.