The most apparent manifestation of selective mutism in children is the failure or inability to speak during certain occasions despite the ability to do so in others. A child with selective mutism, for example, might speak openly to a sibling, but falls abnormally silent when expected to speak to a teacher. Other signs of the communication disorder include shyness, social withdrawal, and awkward motor skills. Patients might also display increased sensitivity to noise, anxiety problems, and a lack of emotional expressiveness. Selective mutism in children might have positive signs, as well; studies show that children with the disorder tend to score higher on measures of intelligence and emotional intelligence.
Selective mutism in children is usually first noticed when the child displays significant changes in speaking behavior in different situations. In very young children, this tends to be expressed in school; specifically, when the child is called upon to recite in class. Other common situations that cause children to fall silent include performances in front of crowds and when spoken to by authority figures. Despite the child's silence in these situations, he appears to have no problem speaking in others.
Some experts believe that selective mutism in children is closely tied to early social anxiety disorders. As such, typical symptoms of social anxiety, such as avoidance of social situations, can be taken as signs of the communication disorder. Symptoms tied to anxiety include abnormal levels of coyness and a fear of public embarrassment.
Other psychologists argue that things are the other way around; they believe that selective mutism in children is the symptom, while social anxiety is the underlying problem. Studies have revealed that selective mutism tends to be accompanied by other anxiety-related problems, such as obsessive-compulsive disorder and social phobias. Due to the overlapping nature of these disorders, signs from one issue can be taken as a sign of another. The tendency to avoid crowds, for example, is considered to be a valid sign of either social phobia or selective mutism in children.
Researchers have found that, despite the difficulty in communication, there might be positive sides to selective mutism in children, both intellectually and emotionally. Children with selective muteness tend to be more curious and perceptive of the world around them, making them exceptional learners. These children also are likely to be more introspective than others, displaying an above-average ability to identify their own feelings and the feelings of others. Experts stress, however, that these relationships are correlational, not causal — selective mutism has not been proven to make children smarter, intellectually or emotionally.