Asch (1951) studies conformity and exposure to normative social pressure using a simple, unambiguous task. For participant there should have been no doubt regarding the correct answer. Participants were shown a standard line and then had to pick which line matched the standard line out of three lines of different sizes. Asch used confederates in his study to create an normative social pressure and they gave the wrong answer in most of the trails. Participants were always last to state their answers. Asch found that 75% of participants conformed at least once and gave the incorrect answer as a result of the confederates also giving that answer. The study lacks population validity with a biased sample of 50 men, he was never able to conclude if females conformed in the same way. On a similar note there is a lack of ecological validity. This task has no reflection of everyday life, we cannot say for certain the effect we have found in lap would actually translate to the real world.