1. Showing participants two large white cards at a time
2. One card had a 'standard line' and the other had three 'comparison lines'
3. Participant asked which of the three lines matched the standard
4. Participants were 123 American male undergraduates
5. Naïve participant tested individually with a group of 6-8 confederates
6. Naïve participant not aware the others were confederates
7. On first few trials confederates gave right answers, then started making errors
8. Confederates instructed to give the same wrong answer
9. Each participant took part in 18 trials, 12 'critical trials' had confederates giving wrong answer
10. A trial was one occasion identifying the length of a standard line