It can happen for personal and social reasons. Personally, people conform because they have expectations for themselves. They might believe that behaving a certain way will help them reach a goal. Conformity can also happen because of other people’s influence. People will conform to be liked or to be a part of a group.
Conformity happens in different levels. Furthermore, the reasons that someone conforms for and what they hope to get out of it, are often linked. Growing up, children learn by copying the behaviours of others. They rely on other’s opinions to be true or on their behaviour to be appropriate. Furthermore, the size of the group matters when conforming.
Sherif (1935) studied how people behave in an unclear situation. In his experiment, participants guessed how far a small point of light on a black screen is moving. This point of light didn’t actually move. It was an optical illusion. First, the participants had to make guesses on their own. Then, they were put into groups of three. There, they changed their answers to fit those of the other two participants better. The researchers made sure that two participants with rather high guesses were put together with a participant with a rather low guess. After, this participant changed his answer to be more similar to the ones of the others. The researchers suggested that this is a sign for conformity. Afterwards, the participants had to make a guess on their own again. There, the answers of their group members from before influenced them, because their guesses were similar to what they had guessed in the group situation. Because of the unclear situation, participants looked at what others were doing. Therefore, they changed their answers to conform to the group.
Researchers criticised Sherif’s study. Because participants had to guess the movement of a point of light that was not actually moving. This meant that there was no right or wrong answer. Being so unsure maybe made participants to conform. 
Asch (1955) wanted to find out if people conformed to other people even if the answer to a question was clear. In his experiment, he showed participants an image of a line. At the same time, he showed them another image with three lines of different lengths. The participants had to choose which line was the same length as the “standard” one, in the first image. 
A control trial showed the task was rather easy. There, the participants made almost no mistakes in matching the correct lines. However, in the main part of the experiment, all except for one participant were confederates. This means that the researcher had told them how to behave during the experiment. They were told to give wrong answers to see how the other participant reacts. The other participant, however, believed that everyone else was also a participant like him. 
The confederates and the participants formed groups of 7 to 9 students. Furthermore, they were asked to match the correct lines 12 times (12 trials). Three-fourths of participants gave the same, wrong answer as the confederates in at least one trial. All in all, participants conformed to the others on an average of 36.8% of the time. These results suggest that more than 3 out of 10 times, the participant was not giving the correct answer, probably in order to conform. 
Normative and InformationalEdit
Deutsch and Gerard (1955) found that people conform for normative and informational reasons.
Normative social influence is when someone changes their behaviour to meet expectations. These can be their own expectations for themselves or the expectations others have for them. The influence will be bigger between people in a group than between two people, for example. Furthermore, the normative influence is smaller when someone feels that there is no need for them to conform. Additionally, not conforming to these expectations can make someone feel scared or guilty.  For example, a small child might laugh with their family even if they cannot understand the joke yet.
Informational social influence is when someone accepts information from others as the truth. The more unsure someone is, the more likely they are to consider other’s opinions as right.  For example, a child might accept whatever new information it is taught by their parents as the truth.
These two types of conformity can work together. In Asch’s (1955) experiment, for example, a participant might be confused because his answer is different from the confederates’ answers. He might feel like he has to normatively conform to the group so that he will not be the only one to stand out. Moreover, he might usually trust his eyes, but this time ask himself if there might be something wrong with his vision. This might lead him to conform to the others informationally because he accepts their answers as right and does not want to be wrong. 
Compliance, Identification and InternalizationEdit
Kelman et al (1958) found different three forms of conformity.
Compliance is when someone conforms because they hope for a positive reaction from others. The person changes their behaviour not necessarily because they agree with it. As a consequence, people who comply might only conform when certain people are present.  In sum, compliance is conforming to others “on the outside”, while maybe not agreeing with them “on the inside”. They do it with the hope of a social effect. For example, a child might sit still during a church service to comply and meet its family’s expectations. In reality, the child might prefer playing outside with the other kids.
Identification is when someone changes their behaviour because they want to make their relationship to another person our group better. They conform in situations that are important for the relationship.  For example, someone might change their behaviour whenever their older cousin visits.
Internalization is when someone changes their behaviour because of the content of the behaviour they conform to. They already agree with the values the behaviour stands for and maybe even find it practical. People conform whenever suitable. They do not care who is present or whether it is needed to conform.  For example, when someone cares for nature with internalization, they might never leave plastic waste anywhere, no matter who is watching them or where in nature they are.
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