Asch (1951) Conformity Experiment

Asch's Study of Conformity

Asch (1951)

In 1951 Solomon Asch designed an experiment to investigate if and why individuals would conform to a majority influence. Using 50 American male students he devised a line perception  task that would test how the participants would response to the social pressure of the majority. He compared his results to 37 control participants.

The experiment was simple. 8 individuals would sit at a table and be shown two cards, one with a single line and the other with 3 lines. The participants had to say, out loud, which line on the second card matched with the first.

The answer was supposed to be obvious, so in this example they should all say it is A.

However, only one of the participants was a genuine participant. The rest of them were confederates, this means they were actors who were “in” on the experiment. The genuine participant would always sit second to last.

There were 18 trials conducted with each participant. The confederates were instructed to give an incorrect answer on 12 out of the 18 trials. Asch referred to these as the critical trials.


In the control group, participants answered in isolation. They were in correct 0.7% of the time. This gives us a good indication that the perception task is easy enough that most of the wrong answers should be a reflection of conformity and social pressure and not because the task was too difficult.

In the critical trials, participant conformed to the majority opinion 36.8% of the time and 75% of participants conformed at least once. Asch concluded that this was due to NSI, the participants conformed to the majority as they wanted to fit in and avoid looking foolish. On interviewing the participants at the end of the experiment they also admitted that they knew the correct answer but conformed with the majority as they did not want to be seen as foolish.

Asch's Variations (1955)

A few years later, Asch decided to replicate his study with several variations. 

He investigated how group size, unanimity (social support) and task difficulty effect the rates of conformity.

If there was only one other person in the room, who was a confederate, the level of conformity fell to 3%. If there were 2 others, the level conformity was 13% and if there were 3 people it was 31.8%.

From these results Asch concluded that the optimum group size to influence an individual is 4 as there was little increase from a group of 4 onwards.

Asch's Variation - Group Size

How group size effected the rates of conformity

No Data Found

When participants had another confederate who agreed with them the levels of conformity dropped to 25%. This shows that the level of social support does effect the levels of conformity. Finally as the level of difficulty of the task increased so did the levels of conformity. This is likely to be due to looking to others for confirmation as we are uncertain of the correct answer. This means we start to conform due to ISI, wanting to be correct.

Contradicting Evidence

Perrin and Spencer (1980) replicated Asch’s study using engineering students. The level of conformity decreased compared to Asch’s original study, only 1 participant conformed out of 396 trials. As they deal with technical drawings on a regular basis, it was assumed that their level of confidence for comparing lines was high. This means we have to consider that the confidence in their own ability can also have an impact on the levels of conformity, not just to pressure from the majority.

They also argues that Asch’s study was “A child of its time”. This was because the study was conducted in the 50s where society was said to be more conformist, likely to be because they had just come out of World War 2. This means we have to question the temporal validity of Asch’s study, this means can we generalise his results to modern day.

Research Design

When designing an experiment we have to consider how we are going to run it, what sample we will use, how many participants we need etc… Different designs have advantages and disadvantages.

Asch’s study was a laboratory experiment. This means it had a high level of control and could easily be replicated. However, laboratory experiments lack ecological validly as they are not real life examples of group pressure. It is very unlikely that you would experience this task and pressure in a real life situation. Fiske (2014) agrees with this and questions the realism of the responses of the participants and suggest they would behave differently outside of a controlled laboratory environment.

As participants knew they were in an experiment they may also influence their responses, positively or negatively, to the experiment. We have to consider these demand charterisitcs when interpreting the results. 

We also have to consider that only male participants were used in his study. Therefore we can not generalise these results across the different genders. Neto (1995) suggests that women would have been more likely to conform as they are more concerned about social relationships.

We should also not assume that these result can be generalised across cultures. Bond and Smith (1996) suggest that levels of conformity would be higher in China compared to USA as they believe the needs/views of the group are greater than that of the individual. 

Finally, Willliams and Sogon (1984) also argue that we may respond differently to a group of strangers compared to a group of friends.


Along with the design of an experiment we must also consider the ethics. Although Asch’s study was mostly ethical there is are a couple of issues. The first is the issue of deception. Participants were not aware that the other participants in the room were confederates. However if the participants knew this then we would have got a very different result so it was necessary to deceive the participants. Due to this deception we could not get fully informed consent. We can work around this by debriefing the participants of the true nature of study at the end. The other issue, although arguably minor, is causing stress to the participants and potentially making them look “stupid” when they conformed to the majority even though the answer was very obvious.