Social norms are regarded as collective representations of acceptable group conduct as well as individual perceptions of particular group conduct.^[1] They can be viewed as cultural products (including values, customs, and traditions)^[2] which represent individuals' basic knowledge of what others do and think that they should do.^[3] From a sociological perspective, social norms are informal understandings that govern the behavior of members of a society.^[4] Social psychology recognizes smaller group units (such as a team or an office) may also endorse norms separately or in addition to cultural or societal expectations.^[5]

In the field of social psychology, the roles of norms are emphasized—which can guide behavior in a certain situation or environment as "mental representations of appropriate behavior".^[6] It has been shown that normative messages can promote pro-social behavior, including decreasing alcohol use^[7] and increasing voter turnout.^[8] According to the psychological definition of social norms' behavioral component, norms have two dimensions: how much a behavior is exhibited, and how much the group approves of that behavior.^[5] These dimensions can be used in normative messages to alter norms (and subsequently alter behaviors). A message can target the former dimension by describing high levels of voter turnout in order to encourage more turnout. Norms also can be changed contingent on the observed behavior of others (how much behavior is exhibited).

Social norms can be thought of as: "rules that prescribe what people should and should not do given their social surroundings" (known as milieu, sociocultural context) and circumstances. Examination of norms is "scattered across disciplines and research traditions, with no clear consensus on how the term should be used."^[9]

Through rulemaking, humans organize and simplify actions/social practices.^[10]

Everyday there are new rules put into place, as well as old rules that are more structured whether it be for a group or an individual. Yet, not only do humans make rules, they strive on finding the rules that come eye to eye about how the world works.^[11] These rules, once accepted by an individual or a group after trial and error, then become a norm.

Groups may adopt norms through a variety of ways. Norms can arise formally, where groups explicitly outline and implement behavioral expectations. Laws or club rules serve as an example of this.^[12] A large number of these norms we follow 'naturally' such as driving on the right side of the road in the US and on the left side in the UK, or not speeding in order to avoid a ticket. Many formal norms serve to provide safety to the general public.

However, social norms are much more likely to develop informally, emerging gradually as a result of repeated use of discretionary stimuli to control behavior.^[13][14] Not necessarily laws set in writing, informal norms represent generally accepted and widely sanctioned routines that people follow in everyday life.^[15] These informal norms, if broken, may not invite formal legal punishments or sanctions, but instead encourage reprimands, warnings, or othering; incest, for example, is generally thought of as wrong in society, but many jurisdictions do not legally prohibit it.

Individuals may also import norms from a previous organization to their new group, which can get adopted over time.^[16][17] Without a clear indication of how to act, people typically rely on their past history to determine the best course forward; what was successful before may serve them well again. In a group, individuals may all import different histories or scripts about appropriate behaviors; common experience over time will lead the group to define as a whole its take on the right action, usually with the integration of several members' schemas.^[17] Under the importation paradigm, norm formation occurs subtly and swiftly^[17] whereas with formal or informal development of norms may take longer.

Groups internalize norms by accepting them as reasonable and proper standards for behaviour within the group. Once firmly established, a norm becomes a part of the group's operational structure and hence more difficult to change. While possible for newcomers to a group to change its norms, it is much more likely that the new individual will adopt the group's norms, values, and perspectives, rather than the other way around.^[13]

Deviance is defined as "nonconformity to a set of norms that are accepted by a significant number of people in a community or society."^[18] More simply put, if group members do not follow a norm, they become labeled as a deviant. In the sociological literature, this can often lead to them being considered outcasts of society. Yet, deviant behavior amongst children is somewhat expected. Except the idea of this deviance manifesting as a criminal action, the social tolerance given in the example of the child is quickly withdrawn against the criminal. Crime is considered one of the most extreme forms of deviancy according to scholar Clifford R. Shaw.^[19]

What is considered "normal" is relative to the location of the culture in which the social interaction is taking place. In psychology, an individual who routinely disobeys group norms runs the risk of turning into the "institutionalized deviant." Similar to the sociological definition, institutionalized deviants may be judged by other group members for their failure to adhere to norms. At first, group members may increase pressure on a non-conformist, attempting to engage the individual in conversation or explicate why he or she should follow their behavioral expectations. The role in which one decides on whether or not to behave is largely determined on how their actions will affect others.^[20] Especially with new members who perhaps do not know any better, groups may use discretionary stimuli to bring an individual's behavior back into line. Over time, however, if a member continues to disobey, the group will give up on him as a lost cause; while the group may not necessarily revoke his membership, they may give him only superficial consideration.^[13] If a worker is late to a meeting, for example, violating the office norm of punctuality, a boss or other co-worker may wait for the individual to arrive and pull him aside later to ask what happened. If the behavior continues, eventually the group may begin meetings without him since the individual "is always late." The group generalizes the individual's disobedience and promptly dismisses it, thereby reducing the member's influence and footing in future group disagreements.

Group tolerance for deviation varies across membership; not all group members receive the same treatment for norm violations. Individuals may build up a "reserve" of good behavior through conformity, which they can borrow against later. These idiosyncrasy credits provide a theoretical currency for understanding variations in group behavioral expectations.^[21] A teacher, for example, may more easily forgive a straight-A student for misbehaving—who has past "good credit" saved up—than a repeatedly disruptive student. While past performance can help build idiosyncrasy credits, some group members have a higher balance to start with.^[21] Individuals can import idiosyncrasy credits from another group; childhood movie stars, for example, who enroll in college, may experience more leeway in adopting school norms than other incoming freshmen. Finally, leaders or individuals in other high-status positions may begin with more credits and be appear to be "above the rules" at times.^[13][21] Even their idiosyncrasy credits are not bottomless, however; while held to a more lenient standard than the average member, leaders may still face group rejection if their disobedience becomes too extreme.

Deviance also causes multiple emotions one experiences when going against a norm. One of those emotions widely attributed to deviance is guilt. Guilt is connected to the ethics of duty which in turn becomes a primary object of moral obligation. Guilt is followed by an action that is questioned after its doing.^[22] It can be described as something negative to the self as well as a negative state of feeling. Used in both instances, it is both an unpleasant feeling as well as a form of self-punishment. Using the metaphor of "dirty hands",^[23] it is the staining or tainting of oneself and therefore having to self cleanse away the filth. It is a form of reparation that confronts oneself as well as submitting to the possibility of anger and punishment from others. Guilt is a point in both action and feeling that acts as a stimulus for further "honorable" actions.

Some research indicates that changes in the weather can increase the likelihood of children exhibiting deviant behavior.^[24]

Norms running counter to the behaviors of the overarching society or culture may be transmitted and maintained within small subgroups of society. For example, Crandall (1988) noted that certain groups (e.g., cheerleading squads, dance troupes, sports teams, sororities) have a rate of bulimia, a publicly recognized life-threatening disease, that is much higher than society as a whole. Social norms have a way of maintaining order and organizing groups.^[25]

Although not considered to be formal laws within society, norms still work to promote a great deal of social control.^[26] They are statements that regulate conduct. The cultural phenomenon that is the norm is the prescriber of acceptable behavior in specific instances. Ranging in variations depending on culture, race, religion, and geographical location, it is the foundation of the terms some know acceptable as not to injure others, the golden rule, and to keep promises that have been pledged.^[27] Without them, there would be a world without consensus, common ground, or restrictions. Even though the law and a state's legislation is not intended to control social norms, society and the law are inherently linked and one dictates the other. This is why it has been said that the language used in some legislation is controlling and dictating for what should or should not be accepted. For example, the criminalisation of familial sexual relations is said to protect those that are vulnerable, however even consenting adults cannot have sexual relationships with their relatives. The language surrounding these laws conveys the message that such acts are supposedly immoral and should be condemned, even though there is no actual victim in these consenting relationships.^[28]

Social norms can be enforced formally (e.g., through sanctions) or informally (e.g., through body language and non-verbal communication cues.) Because individuals often derive physical or psychological resources from group membership, groups are said to control discretionary stimuli; groups can withhold or give out more resources in response to members' adherence to group norms, effectively controlling member behavior through rewards and operant conditioning.^[13] Social psychology research has found the more an individual values group-controlled resources or the more an individual sees group membership as central to his definition of self, the more likely he is to conform.^[13] Social norms also allow an individual to assess what behaviors the group deems important to its existence or survival, since they represent a codification of belief; groups generally do not punish members or create norms over actions which they care little about.^[13][16] Norms in every culture create conformity that allows for people to become socialized to the culture in which they live.^[4]

As social beings, individuals learn when and where it is appropriate to say certain things, to use certain words, to discuss certain topics or wear certain clothes, and when it is not. Thus, knowledge about cultural norms is important for impressions,^[29] which is an individual's regulation of their nonverbal behavior. One also comes to know through experience what types of people he/she can and cannot discuss certain topics with or wear certain types of dress around. Typically, this knowledge is derived through experience (i.e. social norms are learned through social interaction).^[29] Wearing a suit to a job interview in order to give a great first impression represents a common example of a social norm in the white collar work force.

In his work "Order without Law: How Neighbors Settle Disputes", Robert Ellickson studies various interactions between members of neighbourhoods and communities to show how societal norms create order within a small group of people. He argues that, in a small community or neighbourhood, many rules and disputes can be settled without a central governing body simply by the interactions within these communities.^[30]

For Talcott Parsons of the functionalist school, norms dictate the interactions of people in all social encounters. On the other hand, Karl Marx believed that norms are used to promote the creation of roles in society which allows for people of different levels of social class structure to be able to function properly.^[4] Marx claims that this power dynamic creates social order.

Heinrich Popitz is convinced that the establishment of social norms, that make the future actions of alter foreseeable for ego, solves the problem of contingency (Niklas Luhmann). In this way, ego can count on those actions as if they would already have been performed and does not have to wait for their actual execution; social interaction is thus accelerated. Important factors in the standardization of behavior are sanctions^[31] and social roles.

The probability of these actions that are committed are coined to B. F. Skinner, that states that operant conditioning plays a role in the process of social norm. Operant conditioning is the increase that an action will occur again by increasing the reinforced response. This process is that of reward and punishment or trial and error. Hand in hand with deviance, the consequences of one's behavior, whether positive or negative, will determine the probability of reoccurrence as well as the push towards regulating one's decisions in the future. Containing five sub categories, this conditioning treatment is an influence in the actions one commits and the feelings one experiences afterwards. In the case of social deviance, an individual who has gone against a norm will feel the negative connotation that comes with defying the conditioning that was taught therefore indicating negative reinforcement. A good example is that of a little girl painting on the wall of the house as she seeks her mother's approval of her artistic work. When the child witnesses the mother putting her in a "time out", she realizes that if she were to paint on the wall again, it will lead to punishment therefore causing her to notice her negative reinforcement. Therefore, this makes the probability of her painting the wall again, decrease immensely. Skinner also states that humans are conditioned from a very young age on how to behave and how to act with those around us considering the outside influences of the society and location one is in.^[32] Built to blend into the ambiance and attitude around us, deviance is a frowned upon action.

Cialdini, Reno, and Kallgren developed the focus theory of normative conduct to describe how individuals implicitly juggle multiple behavioral expectations at once; expanding on conflicting prior beliefs about whether cultural, situational or personal norms motivate action, the researchers suggested the focus of an individual's attention will dictate what behavioral expectation they follow.^[33]

Descriptive norms depict what happens, while injunctive norms describe what should happen. Cialdini, Reno, and Kallgren (1990) define a descriptive norm as people's perceptions of what is commonly done in specific situations; it signifies what most people do, without assigning judgment. The absence of trash on the ground in a parking lot, for example, transmits the descriptive norm that most people there do not litter.^[33][34] An Injunctive norm, on the other hand, transmits group approval about a particular behavior; it dictates how an individual should behave.^{[33][34][35][36]} Watching another person pick up trash off the ground and throw it out, a group member may pick up on the injunctive norm that he ought to not litter.

Prescriptive norms are unwritten rules that are understood and followed by society and indicate what we should do.^[37] Expressing gratitude or writing a Thank You card when someone gives you a gift represents a prescriptive norm in American culture. Proscriptive norms, in contrast, comprise the other end of the same spectrum; they are similarly society's unwritten rules about what one should not do.^[37] These norms can vary between cultures; while an acceptable greeting in some European countries, kissing a stranger on the cheek constitutes a proscriptive norm in the United States.

Subjective norm is determined by beliefs about the extent to which important others want them to perform a behavior. Social influences are conceptualized in terms of the pressure that people perceive from important others to perform, or not to perform, a behavior.^[36]

Over the last few decades, several theorists have attempted to explain social norms from a more theoretical point of view. By quantifying behavioral expectations graphically or attempting to plot the logic behind adherence, theorists hoped to be able to predict whether or not individuals would conform. The return potential model and game theory provide a slightly more economic conceptualization of norms, suggesting individuals can calculate the cost or benefit behind possible behavioral outcomes. Under these theoretical frameworks, choosing to obey or violate norms becomes a more deliberate, quantifiable decision.

Developed in the 1960s, the return potential model provides a method for plotting and visualizing group norms. In the regular coordinate plane, the amount of behavior exhibited is plotted on the X-axis (label a in Figure 1 ^[77] ) while the amount of group acceptance or approval gets plotted on the Y-axis (b in Figure 1).^[5] The graph represents the potential return or positive outcome to an individual for a given behavioral norm. Theoretically, one could plot a point for each increment of behavior how much the group likes or dislikes that action. For example, it may be the case that among first-year graduate students, strong social norms around how many daily cups of coffee you drink exist. If the return curve in Figure 1 correctly displays the example social norm, we can see that if someone drinks 0 cups of coffee a day, the group strongly disapproves. The group does not approve of member behavior until someone hits four cups of coffee a day; the graduate students (as represented by the return curve) find it excessive to drink more than seven cups, however, as the approval again dips below zero. As exhibited by the coffee example, the return potential model displays for each increment of behavior how much group approval one can anticipate.

Another 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. Rational choice, a branch of game theory, deals with the relations and actions socially committed among rational agents.^[38] 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). 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.^[39] In the Nash equilibrium, no one actor has any positive incentive in individually deviating from a certain action.^[40] Social norms will be implemented if the actions of that specific norm come into agreement by the support of the Nash equilibrium in the majority of the game theoretical approaches.^[40]

From a game-theoretical point of view, there are two explanations for the vast variety of norms that exist throughout the world. 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.