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When there's an audience, people's performance improves -- ScienceDaily

When participants knew an audience was watching, a part of the prefrontal cortex associated with social cognition, particularly the thoughts and intentions of others, activated along with another part of the cortex associated with reward. Together these signals triggered activity in the ventral striatum, an area of the brain that motivates action and motor skills. In essence, the presence of an audience, at least a small one, increased people's incentive to perform well, Chib said, and the brain scans validated this by showing the neural mechanism for how it happens. While people were watching, participants were an average of 5 percent better at the video game -- and as much as 20 percent better. Only two participants didn't perform better in front of others.