Self-categorization theory

Self-categorization theory is a theory in social psychology that describes the circumstances under which a person will perceive collections of people (including themselves) as a group, as well as the consequences of perceiving people in group terms. Although the theory is often introduced as an explanation of psychological group formation (which was one of its early goals), it is more accurately thought of as general analysis of the functioning of categorization processes in social perception and interaction that speaks to issues of individual identity as much as group phenomena. It was developed by John Turner and colleagues, and along with social identity theory it is a constituent part of the social identity approach. It was in part developed to address questions that arose in response to social identity theory about the mechanistic underpinnings of social identification.

Self-categorization theory has been influential in the academic field of social psychology and beyond. It was first applied to the topics of social influence, group cohesion, group polarization, and collective action. In subsequent years the theory, often as part of the social identity approach, has been applied to further topics such as leadership, personality, outgroup homogeneity, and power. One tenet of the theory is that the self should not be considered as a foundational aspect of cognition, but rather the self should be seen as a product of the cognitive system at work.

Drawing inspiration from cognitive psychology, self-categorization theory assumes that the self can be categorized at various levels of abstraction. In other words, humans may categorize the self as a singular "I"(personal identity), or as a more inclusive "we"(social identity). In the latter case the self is cognitively grouped as identical and interchangeable to other stimuli within that category. It is argued that it is this variation in self categorization that underpins many intergroup phenomena, including those described in social identity theory.

To demonstrate the notion of varying levels of abstraction and inclusiveness, three types of self category are often given as examples. The lowest level of abstraction is given as a personal self, where the perceiver self categorizes as "I". A higher level of abstraction corresponds to a social self, where the perceiver self categorizes as "we" in comparison to a salient outgroup (them). A highest level of abstraction is represented by we humans, where the salient outgroup is animals or other non-humans. A common misconception is that these three example categories represent the self categories that humans use. Instead, the theory posits that there are innumerable self categories that a perceiver may use (see, online category formation), and in particular that there are a myriad of different personal and social identities that a perceiver may invoke in his or her day-to-day life. The misconception may also be attributable to the early writing of Turner where a singular social identity was contrasted against a singular personal identity. This however predates the formal statement of self-categorization theory.

In self-categorization theory, categorizing people does not simply involve the redescription of characteristics and categories present in social stimuli. Rather, salient social categories form the basis of a social world that is enriched with meaning. This is achieved through a non-conscious process of accentuation, where differences between social categories are accentuated along with the similarities within social categories. The resulting augmentation of social content allows the perceiver to interact with others with greater confidence and ease.

The accentuation component of self-categorization theory stems from prior research that demonstrated an accentuation effect for categorized non-social stimuli. A prototypical example of non-social accentuation came from Tajfel and Wilkes, who found that when a categorization scheme corresponded to line length participants would view lines belonging to different categories as more different than if no categorization scheme was present. Consistent with the idea that an efficient cognitive system would, where possible, use the same systems regardless of the social or non-social nature of the stimuli, self-categorization theorists have demonstrated similar effects for social stimuli. For example, Haslam and Turner found that a perceiver would describe another person as more or less similar to themselves as a function of the likely categorization scheme.

According to self-categorization theory, depersonalization describes a process of self-stereotyping. This is where, under conditions of social category salience and consequent accentuation, "people come to see themselves more as the interchangeable exemplars of a social category than as unique personalities defined by their differences from others". Under these conditions a perceiver directly bases their behaviour and beliefs on the norms, goals and needs of a salient ingroup. For example, if a person's salient self-category becomes 'army officer' then that person is more likely to act in terms of the norms associated with that category (e.g. to wear a uniform, follow orders, and distrust an enemy) and less likely to act in terms of other potential self-categories. Here the person can be said to be accentuating the similarities between his or herself and other members of the 'army officers' category.

Turner and colleagues stress that depersonalization is not a loss of self, but rather a redefinition of the self in terms of group membership. A depersonalized self, or a social identity, is every bit as valid and meaningful as a personalized self, or personal identity. A loss of self is sometimes referred to using the alternative term deindividuation. Further, although the term depersonalization has been used in clinical psychology to describe a type of disordered experience, this is completely different from depersonalization in the sense intended by self-categorization theory authors.