Tension appears first in the lips, tongue, and jaw, and may spread to other parts of the face, head and neck. Excessive tension can eventually lead to tremors of muscles. Tremors constitute involuntary muscle movements which can cause a person to feel out of control of that particular muscle or out of control of the ability to speak. Tremors can have a powerful effect on the person who stutters and lead the person to seek any possible way to avoid the tremor in the first place or to escape the tremor and the feeling of loss of control. Behaviors such as using sudden, jerky movements to interrupt the tremor, or pushing the muscles or air harder to release the blocked speech, will occur in attempt to release the tremors.
Some clinicians believe that tremors hold the seeds of fear.
The tremors and fear, together, lead the person who stutters into a downward spiral involving layers of covering up and avoiding. A variety of secondary behaviors arise as reactions to the fear of stuttering . People who stutter can build up intense fears in response to the loss of control that they feel or in response to the penalty that they experience from listeners. Avoidance behaviors may constitute the largest group of behaviors developed in response to fear. People who stutter will do a variety of things to avoid a moment of stuttering and the subsequent loss of control and listener penalty.