A Minority of One: Conformity to Group Norms

1. Participant Recruitment

1. Conduct a power analysis and recruit a sufficient number of participants and obtain informed consent from the participants.
   1. The original study included 123 participants in the experimental group and 37 in the control condition.
2. Recruit seven confederates (trained actors), who will serve as the "majority" opinion during each session (which will include a single participant).
   1. Instruct the confederates to simply follow a script in which they purposely make an incorrect judgment on 12 critical trials out of 18 total trials.
   2. Have them make the correct judgment on trials 1, 2, 5, 10, 11, and 14.
   3. Notify them to remain "impersonal" and to not look at the participant after making their correct or incorrect judgment.

2. Data Collection

1. First, create the cards containing lines for the experiment.
   1. For card A, the standard line should be ⅜ in. in width and vary from 2-10 in. in length.
   2. Card B should be placed 40 in. away from card A and should contain three lines-all spaced out 1¾ in. from one another on the card.
   3. The three lines' lengths should vary between 2-10 in., and one should match the standard line on card A.
2. Arrange confederates in two rows of four people.
3. Leave an open spot for a single participant in the second row, 2^nd seat from the left, where they will sit when they arrive for the experiment.
4. Once the participant arrives, explain the cover story of the experiment.
   1. State that the experiment is about testing visual discrimination. All people in the room (confederates + the participant) are shown a pair of cards, card A and card B. Card A has one line on it, and card B has three lines, numbered 1-3, that differ in length. One of those three lines matches the length of the one line on card A. The goal of the task is to judge which of the three lines on B matches the length of the line on A. The experimenter calls on each person to make their judgment (1-3) out loud in sequence. Explain that there will be 18 total judgments made.
5. Begin with trial 1, where all confederates choose the correct line. Ask the confederate on the far left of the first row to call out their answer, and then moving left to right, continue until getting to the participant in the second row.
6. Then ask the participant to provide his answer. Remain indifferent and show no reaction to the participant's answer, even on the critical trials. This process continues for all 18 trials without a break.
7. Make sure that the types of errors made by the confederates are varied on a trial-to-trial basis for the critical trials.
   1. Critical trials 1, 2, 4, 7, 8, and 10 are "moderate" errors where the majority choose the incorrect line that is the second closest to the standard line.
   2. The other critical trials are "extreme" errors in which the majority chooses the line on card B furthest from the standard line.
   3. There is also the option to randomize whether the error made by the majority is an overestimation of the length of the standard line or an underestimation of the length.
8. For the control condition, have participants do all 18 trials, but rather than any public statements of answers for each round, instruct them to privately record their answer on a sheet of paper.
   1. In order to match the group size of the experimental condition, the control participants can be run 8 participants at a time. The responses from all participants in the group can be used as data since there are no critical trials and no confederates.