Is people's behavior best explained by the environment and situation they find themselves in, or by their personality, which guides behavior no matter what the situation is? We knew from the famous Situation vs. Personality Debate that both personality and environment can influence a person, but in Social Psychology, one of the dominant themes is that situations affect our behavior. Human are social creatures and our thoughts, feelings, and behaviors are influenced by the presence of others
A person's behavioral pattern may changes depends on whether one is appreciated by others or not. We call it social facilitation, which is the tendency for people to do better on tasks when in the presence of other people. We might notice in our daily lives that whenever people are being watched by others, they will do well or even better than usual on things that they are already good at doing.
One of a good example about social facilitation in my daily lives was my experience in the gym yesterday. I was lifting weights alone first. Then a friend came over to talk. I was just getting ready to do bench presses at the time. With him watching, I focused more on what I was doing and was able to lift substantially more than I had before. When my friend was watching me did this simple task, I wanted to impress him so I lift more than usual. My behavior changed due to that situation and also exemplified social facilitation.
Your blog has some great information about how our personal performance is increased by those around us. However there also seems to be room for when we know other people are around us, where problems can arise. I think the best example of this was in the book with the Kitty Genovese case. Through this psychologists really emphasized the bystander effect and diffusion of responsibility, which causes groups to act in ways that don't "increase performance."