Conformity according to psychology is the tendency of an individual to follow unspoken rules or behaviours of the social group they belong. Solomon Asch conducted an experiment to investigate the extent to which social pressure from a majority group could affect a person to conform. Allen (1968).
There are several critisms about his theory. Asch used a biased sample, all participants were male of the same age group meaning the experiment lacked population validity. It can not be generalised to a group of women or older people.
Another issue is that the experiment used an artificial task to measure conformity. It is rare that people are faces with such tasks upon a day to day basis. He should have used a more realistic approach for his experiment. Longman (1995)The study therefore had a low ecological validity because the results cannot be generalised to real life situations.
Finally, there are ethical issues: participants were not protected from psychological stress which may occur if they disagreed with the majority.
Evidence that participants in Asch-type situations are highly emotional was obtained by Back et.al. (1963) who found that participants in the Asch situation had greatly increased levels of autonomic arousal. This finding also suggests that they were in a conflict situation, finding it hard to decide whether to report what they saw or to conform to the opinion of others.