In-class experiments #4 : Deception & the Asch Conformity Experiment

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Bringing real social psychology experiments into the classroom is one of the best ways of teaching psychology, but it’s never easy, especially when you need to apply deception in the classroom. But, I was able to pull it off.


[UPDATE September 2018: All teaching materials now shared on the teaching page]


One of the classic social psychology experiments was conducted by Asch (1951) on group conformity. Here’s a brief description of the mythology and results in Asch experiment from PsycWiki (image credit):

aschAsch gathered seven to nine male college students for what he claimed was an experiment in visual perception (Asch, 1955). All were confederates but one, and when he entered the room, the others were already seated in a row (Hock, 2005). After taking his seat, the study began. The experimenter revealed two large white cards: one with a single line (the standard line) and one with three lines of differing lengths (the comparison lines). One of the three lines was the same size as the standard line, and the other two were of varying differences: from three quarters of an inch longer or shorter to one inch and three quarters longer or shorter. Participants were asked to verbally announce which of the three comparison lines was equal to the standard line (Asch, 1955). On the first two trials, the group unanimously answered correctly, but on the third trial, the confederates all gave the wrong answer (Asch, 1955). Each study had 18 trials, 12 of which the confederates gave unanimous incorrect answers (Asch, 1955). They gave correct answers occasionally so that the participant did not suspect collusion (Asch, 1955).

Results – Asch tested 123 different young men from three different institutions of higher learning (Asch, 1955). He found that when alone (the control group) participants made mistakes less than 1% of the time, but in the group situation described in methodology, participants made errors in line judgment 36.8% of the time (Asch, 1955). About one fourth of participants never submitted to the majority, whereas some individuals conformed almost every single time (Asch, 1955). Every participant that conformed to the majority underestimated the frequency of their conformity when interviewed later (Asch, 1955).


To make things more clear, watch this next video :

The Asch Experiment
Watch this video on YouTube.


Since I know that in each of my sessions there are always some that are late, I decide to try and use that in order to run an in-class version of the Asch experiment. I asked my teaching assistant to stand at the door stop late comers from entering the class for 5 minutes which I used to brief the students in class to serve as my collaborators. I used the same task as Asch did with a comparison of one line on the left to the three lines on the right asking the students to indicate which line on the right is most similar to the one on the right. Only, I asked my collaborators to systematically choose the wrong line, with the premise that once I ask a few of them and turn to the late-comers then late-comers would feel the pressure of conformity.


The following four rounds were used :


Asch Conformity Experiment

Asch Conformity Experiment

Asch Conformity Experiment

Asch Conformity Experiment

The students in class were asked to answer : 2, 1, 3, 2 (wrong answers).

After bringing in the late-comers I explained that the purpose of the task was to measure cognitive abilities and then explained the task at hand and went on to run the round. Each round I would – as if randomly – ask a few of the collaborators what their answer was and then choose one of the late comers.

It was quite hard for the collaborators to keep a straight face and there were a few giggles, especially as the late-comers stared at the board and their classmates in disbelief. While in the four rounds no student “gave in” and they all answered what they really saw it was apparent that the lag in their answers increased and the expression on their faces turned more concerned. After the four rounds I asked the late-comers about what they experienced and it became clear that the conformity effect was indeed taking place and greatly confusing them upto a real dilemma as to whether to answer in a truthful way or according to group pressure.

Point made, class dismissed.


To read a bit more on the Asch experiment:


If you’re considering on running this, then perhaps running a few more rounds would have shown the effect in full force. Try this out with your students and tell me how well it worked for you.

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Lisa Blake
5 years ago

I’m going to try this today – thank you so much for this resource! Is there a way to print this? I’ve tried and it’s all jumbled together. Thanks