Final answer:
Social facilitation is the phenomenon where the presence of others enhances performance. It is more likely to occur for well-learned tasks because of increased confidence and arousal levels.
Step-by-step explanation:
Social facilitation is the phenomenon where the presence of others enhances an individual's performance on a task. It is more likely to occur with a well-learned task because a person is confident and experienced in that particular task. The presence of others can provide an audience effect, increasing arousal levels and leading to improved performance on tasks that the individual has already mastered.