One can not conclude immediately that people behave the way they do because of their personalities, their motivational structures, the way they were raised, or their pattern of past experiences. It turns out that people sometimes behave the way they do largely because of the social situation in which they find themselves. Therefore, when one wishes to change some aspect of one's life, one had better look also to aspects of the situation rather than merely to the specific people who behave in the situation. Behavior which is characteristically human is social. Indeed, it is difficult to imagine any form of human behavior which is not in part socially determined or which does not influence the behavior of other people.
Social psychology is the systematic application of basic psychological principles to human behavior.
To be sure, many of our psychological principles have been generated from lower animals in confined, carefully controlled laboratory settings. The problem of generalizing from this research to humans is a difficult one. We will have to decide which principles can be generalized, and how far they can be generalized. And we will learn that social psychological principles have much to contribute to research with lower animals. Some important principles from the animal laboratory have had to be greatly modified or at least seriously qualified on the basis of social psychological research.