Social identity theory is the study of the interaction between personal and social identities in social psychology. The goal of social identity theory is to specify and predict the circumstances under which people perceive themselves as individuals or as members of groups. The theory also takes into account the effects of personal and social identities on individual perceptions and group behavior.
apostrophe because an apostrophe is a figure of speech in which the speaker or writer addresses an inanimate object or an abstract concept. In this case it refers to an inanimate object.
