The monitoring hypothesis posits that social facilitation effects do not occur when the performer is familiar with the observers or the situation. This is because, in those cases, the performer knows how the observer will respond or how the situation will take place. Therefore, in such situations the performer's arousal will not increase. So, if the person is unfamiliar with the observers or the situation, he/she will experience uncertainty and arousal will increase, but not if he/she is familiar with them.