The presence of others disrupts your ability to learn.

While an audience can improve performance on familiar, well-learned tasks, their presence often impairs performance on novel or complex ones.

According to Zajonc (1965), audience-induced physiological arousal increases the likelihood of performing a 'dominant response.' When a task is well-learned, the dominant response is correct, leading to facilitation; when a task is novel or complex, the dominant response is incorrect, leading to inhibition.