Why do I start stuttering when nervous?

When you are nervous, your attention is dispersed. A part of your attention may be on the situation at hand, but other parts of it are on self-perceptions, your perception of others’ perception of you, previous negative experiences, and negative thoughts and hypotheses. When your full attention is not on speaking, there is a likelihood that your words will not come out as intended. Moreover, when you’re nervous, your breathing can become irregular, directly impacting the air-contact coordination. Considering that speech is a delicate dance between airflow and interior mouth contact, it requires awareness, control and balance.