Norm (sociology)

A Social norm is the sociological term for the behavioral expectations and cues within a society or group. They have been defined as "the rules that a group uses for appropriate and inappropriate values, beliefs, attitudes and behaviors. These rules may be explicit or implicit. Failure to stick to the rules can result in severe punishments, the most feared of which is exclusion from the group."[1] They have also been described as the "customary rules of behavior that coordinate our interactions with others."The social norms indicate the established and approved ways of doing things, of dress, of speech and of appearance. These vary and evolve not only through time but also vary from one age group to another and between social classes and social groups. What is deemed to be acceptable dress, speech or behavior in one social group may not be accepted in another. Deference to the social norms maintains one's acceptance and popularity within a particular group; ignoring the social norms risks one becoming unacceptable, unpopular or even an outcast from a group. What is deemed acceptable to young people is often unacceptable to elderly people; this difference is caused by the different social norms that operate and are tacitly agreed-upon in such different groups of people. Social norms tend to be tacitly established and maintained through body language and non-verbal communication between people in their normal social discourse. We soon come to know when and where it is appropriate to say certain things, to use certain words, to discuss certain topics or wear certain clothes and when not to. We also come to know through experience what types of people we can and cannot discuss certain topics with or wear certain types of dress around. Mostly this knowledge is derived experimentally.
Overview
Social norms can also be viewed as statements that regulate behavior and act as informal social controls. They are usually based in some degree of consensus and are maintained through social sanctions. In order to explain the content of normative rules, three different models are identified:
 * Focus on the actions of one's personal ego,
 * Focus on ego's reactions to actions of alter, and
 * Negotiation between ego and alter.
Norms are rules of behavior. They exist as both formal and informal norms, but often the later is found to be more strong and reinforced. These informal norms are divided into two:
 * Folkways: Informal rules and norms whose violation is not offensive, but expected to be followed. It's a kind of adjusting, accommodating type of habits. It does not invite any punishment or sanctions, but some reprimands or warnings.
 * Mores: They are also informal rules which are not written, but results in severe punishments and social sanction upon the individuals like social and religious exclusions.
A general formal framework that can be used to represent the essential elements of the social situation surrounding a norm is the repeated game of game theory.
A norm gives a person a rule of thumb for how they should behave. However, a rational person only acts according to the rule if it is optimal for them. The situation can be described as follows. A norm gives an expectation of how other people act in a given situation (macro). A person acts optimally given the expectation (micro). In order for a norm to be stable, people's actions must reconstitute the expectation without change (micro-macro feedback loop). A set of such correct stable expectations is known as a Nash equilibrium. Thus, a stable norm must constitute a Nash equilibrium. 
There exist various norms throughout the world. What accounts for the vast variety? From a game theoretical point of view, there are two explanations for this. One is the difference in games. Different parts of the world may give different environmental contexts and different people may have different values, which may result in a difference in games. The other is equilibrium selection not explicable by the game itself. Equilibrium selection is closely related to coordination. For a simple example, driving is common throughout the world, but in some countries people drive on the right and in other countries people drive on the left (see coordination game). A framework called comparative institutional analysis is proposed to deal with the game theoretical structural understanding of the variety of social norms.