In today's group I mentioned the Asch line study. Here is a video describing the experiment:
What I wish is that Dr Tantam would have explained how his theory holds up when there is an ally who gives the correct answer, or when the conditions are changed to reduce group pressure, which increases the chance that the unsuspecting participant will stick to their correct answer instead of giving in to pressure from the group. There is no "leader" exerting control in any of these situations, so there is something else going on here that I don't think is well explained in this chapter which focuses mostly on examples of tyrants who exert a powerful influence on groups of people, convincing them to commit atrocities.