I think that the biological drive that we have to form groups also has a direct correlation with conformity. The need to belong or form groups seems ridiculous when we look at it from outside of any given situation because we want to believe that we are independent individuals. In the book, it says that the threat of social isolation can lead us to behave in self-destructive ways and even impair our mental functioning. When I first read this, I thought that statement seemed a bit exaggerated, however, after thinking about it, I realized just how rarely I do things by myself. Even something as simple as going to the bathroom at a sporting event or party, most people, including myself, almost always ask the people they are with if anybody else has to go.
Although it may seem unnecessary looking back, asking someone to accompany you to the bathroom is a harmless act. Unfortunately, sometimes a group setting can involve very harmful acts as well. For instance, the art of peer pressure and conformity when it comes to deciding whether or not you want to participate in an illegal activity with a group of friends. Your conscious tells you not to, however, your desire for acceptance takes over and you find yourself doing things you would not normally do.
Psychology: From Inquiry to Understanding
Chapter 13, Page 495, "The Need to Belong: Why We Form Groups"
I also agree that basing your decisions on what others will think or doing things only for that reason can greatly impair judgement. It's probably one of the reasons why teens especially often make poor decisions. Peer pressure can cause us to overlook many important things. For myself, sometimes I'll go out with my friends because I feel pressured, even if I'm tired, and then instantly regret it.