Mob mentality is usually portrayed as a negative action but in many ways it can have a very positive impact. A flash mob is a very good example, this installs happiness and can be very uplifting. Also peaceful protests could have a huge impact and really make a change. Protests and rallys, such as the push for gay and lesbian rights, have actually come thought and people have starting changing traditional ways because of these followings. An example of progressive mob mentality in Lord of the Flies is how the boys come together (or in two separate groups) and strive for survival. All the hunters get hyped up and feed off each others adrenaline when they are trying to catch a pig, that the idea of being in a group highlight. If they weren't in a group they might not have food to eat.
There are plenty positive examples of mob mentality but the negative actions out weigh them. In the real world, gangs who come together can do much more damage then individually. Also events such as presidential rallys can create violence because supporters feel like they are backed by a group. In Lord of the Flies mob mentality invades the minds of the boys on the island. When the hunters are all together they turn more savagery than ever. In the last few chapters the hunters have gone over the top, not just to survive but to prove themselves as individuals and part of the group. Also the hunters played a "game" where Robert acted like a pig and they would encircle and "kill" him. The thing is, this act isn't just a "game", They didn't kill Robert, but they did hurt him and even went to the extent of describing other games they could play. These negative aspects of mob mentality are tearing apart the group.