What does Scout learn about mob mentality?

Mob mentality occurs when a group of people who have the same thing in mind are driven by a single cause or emotion to react as a group to a situation.  It is as if a group becomes one mind, one emotion.  When the mob approaches the jailhouse to lynch Tom Robinson, they are acting as a mob.  Peer pressure from the other mob members keeps them focused on the act of hanging Tom Robinson.  When Jem, Scout, and Dill show up to the attempted lynching, the presence of children in this violent group causes the mob to pause.  Jem refuses to leave despite Atticus pleading for him to go home.  It is then that Scout steps in and points out Walter Cunningham’s father in the crowd.  By pointing out Mr. Cunningham, the emotional “spell” of the mob mentality is broken.  Scout tells Mr. Cunningham to say “hey” to Walter, and the reference to his son makes Mr. Cunningham reconsider what he was about to do.  People are typically more courageous with a group of people than they are as individuals.  Scout reduces the mob to individuals who then feel regret for trying to carry out this violence in front of innocent children.  The mob mentality breaks down, and the mob is reduced to individual men who don’t want to be known for the deed they were about to do.