Social facilitation
Social facilitation is the tendency for people to perform differently when in the presence of others than when alone. Compared to their performance when alone, when in the presence of others, they tend to perform better on simple or well-rehearsed tasks and worse on complex or new ones. The Yerkes-Dodson law, when applied to social facilitation, states that "the mere presence of other people will enhance the performance in speed and accuracy of well-practiced tasks, but will degrade the performance of less familiar tasks."