The term 'refusal to speak' can be summarized as MUTISM, which is a condition in which a person is unable to speak or communicate verbally. MUTISM is usually caused by psychological trauma, such as extreme shyness or fear, and can also be caused by physical trauma, such as a stroke or brain injury. It can also be caused by certain medical conditions, such as autism or cerebral palsy. MUTISM can be temporary or permanent, depending on the cause.