In Ferguson, Mo., after Officer Darren Wilson was cleared of any wrongdoing in the shooting death of unarmed teenager Michael Brown, riots ensued.
On Monday night stores were looted, fires were started and violence was rampant in the Missouri town.
Paul Susac, a mental health counselor who studied group mentality says that this type of behavior is part of human nature. Susac tells us it's important to look at context when it comes to mob mentality.
"We're looking at a minority group that's being arguably oppressed by the power structure of society," says Susac. According to Susac group mentality starts with everyone's individual experiences. In this case probable experiences of members of the community when dealing with law enforcement. "There's individual experiences of humiliation, of oppression and discrimination and prejudice."
He likens the Ferguson shooting and grand jury's decision to "lightening rods" where the community comes together as a group around the issue.
"That community did a really good job of holding it together and not expressing their anger through rioting or violence for a really long time with every expectation that justice would be served," says Susac. "Their perception now is that justice was not served."
He describes what follows as "de-individuation", which means that in a way the individual loses his or her identity within the group. "It becomes safer to express your anger, resentment, and hostility in that group dynamic."
According to Susac, riots happen because people feel powerless and in order to be heard they band together and raise their voices, so to speak. While this can have negative and dangerous results Susac says that much of mans' best work is done with group mentality so it should not be viewed as a purely bad thing.