Social influence occurs when an individual's thoughts or actions are affected by other people. Social influence takes many forms and can be seen in conformity, socialization, peer pressure, obedience, leadership, persuasion, sales, and marketing. Harvard psychologist, Herbert Kelman identified three broad varieties of social influence.
- 1. Compliance is when people appear to agree with others, but actually keep their dissenting opinions private.
- 2. Identification is when people are influenced by someone who is liked and respected, such as a famous celebrity or a favorite uncle.
- 3. Internalization is when people accept a belief or behavior and agree both publicly and privately.
Morton Deutsch and Harold Gerard described two psychological needs that lead humans to conform to the expectations of others. These include our need to be right (informational social influence), and our need to be liked (normative social influence). Informational influence is an influence to accept information from another as evidence about reality. Informational influence comes into play when people are uncertain, either because stimuli are intrinsically ambiguous or because there is social disagreement. Normative influence is an influence to conform to the positive expectations of others. In terms of Kelman's typology, normative influence leads to public compliance, whereas informational influence leads to private acceptance.
Social influence can also be described as power - the ability to influence a person/group of people to one's own will. Usually people who possess beauty, significant sums of money, good jobs and so on will possess social influence on other, "ordinary" people. So even if the person doesn't possess any "real" or political power but possesses the things listed above (good looks, money, etc.), he could persuade other people into doing something. However, good looks are not solely why attractive people are able to exert more influence than average looking people, e.g. confidence is the by-product of good looks. Therefore, the individual's self-esteem and perceived Persona is the critical factor in determining the amount of influence one exerts.
Those with access to the media may use this access in an attempt to influence the public. For example, a politician may use speeches to persuade the public to support issues that he or she does not have the power to impose on the public. This is often referred to as using the "bully pulpit".
Another example would be movie stars, who do not usually possess any political power but are familiar to many of the world's citizens and therefore possess social status. They get a lot of media coverage and they may have many enthusiastic fans.
In the case of peer pressure, a person is convinced to do something (such as illegal drugs) which they might not want to do, but which they perceive as "necessary" to keep a positive relationship with other people, such as their friends.
Psychological manipulation refers to attempts to change another person using methods which are exploitative, devious, deceptive, insidious or unfair. Manipulation is always one-sided, unbalanced or unsymmetrical. Manipulation advances the interests and furthers the goals of the manipulator only, often at the victim's expense.
Those perceived as experts may exert social influence as a result of their perceived expertise. This involves credibility, a form of social influence from which one draws upon the notion of trust. People believe an individual to be credible for a variety of reasons, such as perceived experience, attractiveness, etc. Additionally, pressure to maintain one's reputation and not be viewed as fringe may increase the tendency to agree with the group, known as groupthink.
In 2009, a study concluded that fear increases the chance of agreeing with the group, while romance or lust increases the chance of going against the group. When love strikes in a group the two who are together feel like they have to make their own stand and that is what mainly causes them to diagree.
In his book, The Tipping Point, Malcolm Gladwell discusses the way new ideas are transmitted by social influence. New products or fashions are introduced by innovators, who tend to be creative and nonconforming. Then early adopters join in, followed by the early majority. By this time, a substantial number of people are using the idea or product, and normative and informational influence encourages others to conform as well. The early majority is followed by a second group that Gladwell calls the late majority, and then finally by the laggards, who tend to be highly conventional and resistant to change.
There are varying social structures within online communities that determine the interaction between influencer and follower.  The following are classifications of social structures in which influencers operate:
- Pyramid - Reciprocity is not the primary objective in a pyramid-shaped social structure. Typically users have a passive relationship with one another. Often cited as a prime example of this social structure is Twitter. Influencers such as CNN and the NY Times garner millions of followers. It is these followers that provide the support structure for the influencers (the capstone to the pyramid). The more followers a user has, the larger their pyramid stands.
- Circular - The central element in a circular social structure is reciprocity. Consider the analogy to Ring Around the Rosie. Users can identify and communicate with everyone in their immediate circle. Facebook is an often-cited example of a circular social structure. Where Twitter you might follow 300 brands, typically Facebook users befriend only a select number of people or brands.
- Hybrid - This social structure combines the circular and pyramid-shaped community framework. Users will form micro-communities based on particular websites or topics. Digg is an example of a hybrid social structure. Within a category, there will emerge a tight group of influencers that band together to promote content.
- Kelman, H. (1958). Compliance, identification, and internalization: Three processes of attitude change. Journal of Conflict Resolution, 1, 51-60.
- Deutsch, M. & Gerard, H. B. (1955). A study of normative and informational social influences upon individual judgment. Journal of Abnormal and Social Psychology, 51, 629-636.
- Ivory Tower Unswayed by Crashing Economy. New York Times.
- EurekAlert. (2009). Fear or romance could make you change your mind, U of Minnesota study finds.
- Gladwell, M. (2000). The Tipping Point: How Little Things Can Make a Big Difference, first published by Little Brown. ISBN 0-316-31696-2
- Differing Approaches to Social Influence