1. Participants were tested in groups of 6 to 8
2. Each group was presented with a standard line and three comparison lines
3. Participants had to say aloud which comparison line matched the standard line in length
4. In each group there was only one genuine (naive) participant, the remaining were confederates
5. The genuine participant was seated second to last and did not know the other participants were fake participants
6. The fake confederate participants all gave the same incorrect answer
7. Confederates were told to give the incorrect answer on 12 out of 18 trails