Doing What Others Do – Peer Influences

Groups are by their very nature a number of people who share various things. Groups are held together by shared values, common goals, similarities among members and, most importantly, norms. The norms of a group are both formal and informal. The two types of rules can coexist without any real issues. Formal norms are the written rules that all members of a group have to respect and obey. For example if the social group Manchester United Football Fans Organization has a rule book that each and every member has to comply to. Such a rule might be something like this: All members of the group will never support Manchester City. Manchester City and Manchester United are rivals and a rule that forbids fans of United to support City is more than plausible.

At the same time, the Manchester United Football Fans Organization might have some informal rules such as the members of the group to supporting each other in difficult moments of their lives. For example, there can be an unwritten rule that in case of members needing money for a sick member of their family or for a funeral or wedding, the group gathers its financial resources and collects money for the one in need.

Formal and informal rules are at play in large groups such as societies. Across the world there are formal rules in the form of laws. All societies forbid theft and murder through formal rules. At the same time in all societies there are informal rules that govern social life. One simple example is reciprocity. If you are invited for dinner at someone’s house, it is normal for you to bring a gift for the hosts.

People are allowed to conform or not to both formal and informal rules of society. When not conforming to formal rules such as laws, people are usually punished. For example, if a member of the Manchester United Football Fans Organization goes to a Manchester City football match and cheers for City, then he will be punished by the Manchester United Football Fans Organization. Very likely, in the book of rules of this organization there is a punishment for cheering for Manchester City.

When a person does not conform to informal rules, there is also a potential punishment. This punishment, however, is not based on a written book of rules, but rather takes the form of social exclusion. For example, if a member of Manchester United Football Fans Organization refuses to contribute to the collection for one its members who has a sick child, then the person who refused will not be punished with a sanction from the book of rules, but will be marginalized by other members of the group who will forget to invite him to their next barbecue party.

Up to now, you have learned about formal and informal rules and about one motivation for conforming to them, namely the potential punishment. Indeed people do not want to be punished neither formally nor informally. At the same time, fear of punishment is not the only motivation for conforming to formal or informal norms.

As mentioned in earlier chapters, people have a natural drive for being in a social group. The natural drive is not powered by fear. Of course fear of exclusion plays a role, but most people comply with social norms because it is simply natural to do so.

Peer influences on human behavior are two folded. First, there is social pressure: conforming to group norms in order to not feel or be excluded (including standing out). Second, there is social proof: conforming to group norms because people believe that others know something that they don’t. Both social pressure and social proof have the same outcome, namely that people conform to group norms and in the end they do what others do. However, the mechanisms that lead to this outcome are distinct in social pressure and in social proof. In the remainder of this chapter I will present both social pressure and social proof and discuss their similarities and differences.

Social Pressure

Conformity to group (informal) norms through social pressure was demonstrated by psychologist Solomon Asch in the 1950s in a series of experiments which have been informally named Asch’s lines experiment. To briefly describe the experiment, take a look at the next picture. The question asked in the experiment was a trivial one: With which of the right hand lines is equal to the left hand line? Unless you are blind or have a serious seeing problem and not wear your glasses the answer is clear as daylight.

Your answer is “A” and correctly so. But there is a bit more to this experiment than just testing one’s visual ability. Imagine that you are in a room with another five people who are, as far as you know, just like you (peers). Every person gives the answer out loud and you are the last to respond. Your peers’ answers are as follows:

Person 1 Answers: “B”;

Person 2 Answers: “B”;

Person 3 Answers: “B”;

Person 4 Answers: “B”;

Person 5 Answers: “B”;

It is time to give your answer. What will it be: “A” or “B”? Now, with you reading this alone you might think that you will definitely say “A” (which by the way is correct, while “B” is not), but when in a room with five other people just like you all saying “B”, there is a good chance that you will conform and give the erroneous answer “B”. You might wonder why all the other five people just like you gave the erroneous answer “B”. The explanation is that the other five people are not actual participants in the experiment like as you are. They are hired by the experimenter and instructed to give the wrong answer. The only real participant in the experiment is you, participant number six.

There are numerous versions of this experiment and what they have shown is that about 75% of people conform at least once and give the wrong answer that the other participants were instructed to give. There are some nuances to the conclusions of the experiment.

First, people conform only when the answers are public – spoken out loud; when asked to write down the answer, virtually no one gives the wrong (group) answer, thus when an action is private the level of conformity to informal norms due to social pressure decreases.

Second, if at least one person out of the previous five gives the correct answer, then the last participant (who is the only real participant) will be less likely to conform to the group’s norm. In other words, if at least one person does not conform to a social norm, then the influence of peer pressure diminishes significantly.

One particular criticism of these results it that the experiment itself is the product of social norms of the US society in the 1950s. The counterargument suggests that students (who were the participants in the experiment) in the 1950s were more likely to conform than students in the 1990s since there have been consistent changes in the society overall. My opinion is that this criticism has some value in the sense that in today’s society there is a larger variety of norms that we conform to. For example, non-conformists that buy “Apple” products do not conform to the norm of majority, but conform to the norms of a minority. At the same time, conformity to social norms still exists.

The most interesting aspect about the Asch experiments is that the correct answer is obvious. Everyone sees and knows the correct answer. Moreover, the real participants in this experiment had no connection with the hired actors (the first five people giving the answer) and there was no formal group. These characteristics of the study might seem frivolous, but the main strength of the results comes from this very feature. If 75% of people are willingly and consciously giving the wrong answer at least once to a simple question because people whom they have never seen and will never meet again in their lives, just imagine what happens in the real world. In the real world, however, we encounter numerous situations in which the correct answer is not straightforward. Moreover, more often than not we are in the company and under the influences of other people who are not indifferent to us.

Social Proof

In the previous section you have learned about social pressure. At the same time, you know that we tend to conform to social norms and do what others do not only to avoid feeling excluded, but simply because we infer that others know better. This is social proof.

Imagine the following example. You are in a foreign country and want to buy pasta from a supermarket. None of the brands on the shelves are known to you and you don’t know the language of the country, so you can’t read too much on the packages. As you are looking at the pasta bags and packages trying to figure out which one to buy, a lady comes by the shelf with pastas and picks one bag, puts it in her shopping basket and leaves. The lady looks more like a local and a lot less like a tourist.

How likely are you to pick up the same type of pasta as the lady did?

My belief is that you are very likely to buy exactly the same type of pasta as the lady did. This is not because you are afraid that if you would not pick the same type of pasta you would be or feel excluded from a social group. After all you are in a foreign country, you don’t speak the language and have no idea what kind of pasta is the best… how more excluded can you get?

You will pick up the same type of pasta as the lady picked because you infer that she knows something you don’t, namely which pasta is better.

The main distinction between social proof and peer pressure is that social proof occurs only when there is some ambiguity, whereas peer pressure occurs even in situations in which there is no ambiguity (remember that in the Asch experiment the correct answer was straightforward). When there is some ambiguity, we infer that others know better, but this implies that we ourselves don’t know too much. In the pasta example, you inferred that the local lady knows which pasta is best because you yourself have no idea which one is better.

Peer pressure, on the other hand, acts even if you know exactly which pasta is better. Let’s assume that you go to the supermarket to buy pasta and this time you know that brand B is the best pasta in the world. However, you are not alone on your shopping trip and your in laws are with you. They are also shopping. Your mother in law picks up some pasta brand A (which you know is inferior to brand B). Then your sister in law picks up the same brand A pasta… now even if you know brand B is better, there is a good chance that you will buy brand A in order to not be excluded by your extended family.

There are two main similarities between social pressure and social proof. First, the power of both peer influences and of social proof increases with the number of peers exhibiting a certain behavior. To illustrate this for social pressure, imagine that you are the real participant in the Asch experiments, but there aren’t five people who give their answers before you do; there is only one. How likely are you to give the same wrong answer as the previous person did? Well, you will still be influenced by the previous person’s answer, but the likelihood of you yielding to the pressure of only one person is smaller than the probability of yielding to the pressure generated by five people. Putting things simpler, the social pressure increases with the number of people who exercise the pressure.

In the case of social proof becoming more powerful with the number of people exhibiting a behavior, a wonderful illustration comes from Stanley Milgram, Leonard Bickman and Lawrence Berkowitz who have published a study on this very issue in 1969. In this study, the researchers hired actors to go on a street corner and simply look up at the sixth floor of a building. They were interested in the percentage of passersby who would stop and look up. When there was only one hired actor that looked up, 45% of the passersby stopped and looked up. However, when there were fifteen hired actors that looked up, 85% of the passersby stopped and looked up. The power of social proof increases with the number of people who exhibit a certain behavior.

The second similarity between social proof and social pressure is that their influences are dependent on the similarity between us and the people who exhibit a certain behavior. The more similar we are to the others, the higher the power of both social pressure and social proof is. For example, a Manchester City fan will not be influenced by the behavior of a Manchester United fan as long as this dissimilarity is salient. At the same time, if Jessica is a student in psychology and students from the psychology institute start wearing blue clothes, it is very likely she will start wearing blue clothes too. However, if the business administration students start wearing red clothes, then for sure Jessica will not wear red clothes.

To summarize on social pressure and social proof, both lead to the same outcome of doing what others do. The processes through which this outcome is obtained are different. In the case of social pressure, people conform to group norms even if there is no ambiguity on the subject of behavior. People conform in order to not feel and be excluded. In the case of social proof, people conform to norms when there is some ambiguity on the subject of behavior.

People conform because they infer that others know something they don’t. Both social pressure and social proof are influenced by the number of people who exhibit a behavior and by the level of similarity between us and the people who exhibit the behavior.

Before going into the practical implications of peer influences, one thing should be clarified. I made a distinction between social pressure and social proof because the psychological processes behind them are distinct. At the same time you have learned that they are similar in two ways and both social pressure and social proof end up in people doing what others do. In real life, quite often, these two phenomena co-occur and both influence human behavior.

Practical Implications of Peer Influences (Social Proof and Social Pressure)

The practical implications of peer influences are numerous and we encounter them at every step. Let’s see some examples.

First, you might have noticed that on websites there is a Facebook area where you see who Likes the page. The script behind is designed in such a way that you see the Facebook friends who Like the page in the list. This is well designed since if you see that some of your peers (or at least people you know) like the page you will be more likely to give a Like to the page. The unconscious reasoning goes something like this: If my friends like this, then there might be something interesting here for me too.

Second, if you ever shopped on Amazon or searched a movie on, then you might have noticed the area that says People who bought this also bought / viewed this. In this case, the only thing that you have in common with the group is that you and they have a common interest – bought or viewed something. Despite this very weak link, these recommendations have the desired effect, namely to at least look at another product and sometimes buy it.

Third, in many advertisements or marketing communication materials there is a mention of X thousands / millions satisfied customers. This is another way to say that The social norm is to buy our product and it is aimed at making you conform to this norm.

Fourth, in both online and offline shopping environments a certain product is mentioned as Popular choice which has the same meaning as the X million satisfied customers.

Fifth, especially in the online environment, but not exclusively, you can find user ratings which are another form of establishing a norm. The unconscious reasoning goes like this: If other people say this is a 8.5 (on a scale from 1 to 10) product, then it must be reasonably good. Moreover, some websites also say how many evaluations have been made. The more people say something is good or bad, the stronger the norm is.

Up to now, I gave a lot of examples related to marketing, but conformity to social norms has by far many more applications. One of my favorite examples of using conformity to social norms is in the public transport system in Rotterdam, The Netherlands. Everyone checks in and out of the tram or bus and thus not doing so (free-riding) is diminished by the social pressure. This is not the only factor that influences honest behavior, but it is one of them.

What we have to be aware of is that conformity to social norms has a very serious Dark side. We know that people conform to social norms or in other words go with the group. What is essential is which norm people conform to. I am originally from a country which (still) has serious issues with corruption and at least part of this phenomenon is based on social norms. Of course the formal norms – laws – are against corruption, but there still are informal norms which go for corruption and not against it. I will not expand on this topic since it is not my purpose to analyze corruption behavior. The key is that conformity to norms does not always mean that people conform to the right norm.



Asch, S. E. (1956). “Studies of independence and conformity: A minority of one against a unanimous majority.” Psychological Monographs, 70.

Milgram, S., Bickman, L., & Berkowitz, L. (1969). “Note on the drawing power of crowds of different size.” Journal of personality and social psychology, 13 (2), 79–82.

Figure 4. Example of the stimuli used in the Asch experiments on social conformity

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