but there are no definitive answers yet due to the under-diagnosis and small/biased sample sizes. Many people are not diagnosed until late in childhood only because they do not speak at school and therefore fail to accomplish assignments requiring public speaking. Their involuntary silence makes the condition harder to understand or test. Parents often are unaware of the condition since the children may be functioning well at home. Teachers and pediatricians also sometimes mistake it for severe shyness or common stage fright. Most children and adults with selective mutism are hypothesized to have an inherited predisposition to anxiety. They often have inhibited temperaments, which is hypothesized to be the result of over-excitability of the area of the brain called the amygdala. This area receives indications of possible threats and sets off the fight-or-flight response. Behavioral inhibitions, or inhibited temperaments, encompass feelings of emotional distress and social withdrawals. In a 2016 study, the relationship between behavioral inhibition and selective mutism was investigated. Children between the ages of three and 19 with lifetime selective mutism, social phobia, internalizing behavior, and healthy controls were assessed using the parent-rated Retrospective Infant Behavioral Inhibition (RIBI) questionnaire, consisting of 20 questions that addressed shyness and fear, as well as other subscales. The results indicated behavioral inhibition does indeed predispose selective mutism. Corresponding with the researchers’ hypothesis, children diagnosed with long-term selective mutism had a higher behavioral inhibition score as an infant. This is indicative of the positive correlation between behavioral inhibition and selective mutism. Given the very high incidence of social anxiety disorder within selective mutism (as high as 100% in some studies), it is possible that social anxiety disorder causes selective mutism. Some children or adults with selective mutism may have trouble processing sensory information. This could cause anxiety and a sense of being overwhelmed in unfamiliar situations, which may cause the child or adult to "shut down" and not be able to speak (something that some autistic people also experience). Many children or adults with selective mutism have some auditory processing difficulties. About 20–30% of children or adults with selective mutism have speech or language disorders that add stress to situations in which the child is expected to speak. In the DSM-4, the term “elective mutism” was changed to “selective mutism.” This name change intended to deemphasize this refusal and oppositional aspect of the disorder. Instead, it highlighted that in select environments, the child