Selective mutism

Selective mutism (also referred as SM) is an anxiety disorder where a person normally cannot speak in specific situations, specific places, or to specific people if a certain condition is triggered. Selective mutism usually happens while the person has a social anxiety disorder. Children and adults with selective mutism are fully capable of speech and understanding language but simply cannot speak because they physically cannot speak in certain settings. People with selective mutism stay silent even when the consequences of their silence include shame, social rejection, or punishment. 

References

Category:Anxiety disorders