I am not sure of something that shows that it is uninterpretable but I wanted to tell you a bit about vocabulary. You can have a fantastic vocabulary and still have a language delay or what would appear to be an expressive language disorder on an IQ test. Some kids with language delays talk around definitions rather than give definitions directly. It is because they cannot find the appropriate words they want to use but they have extensive vocabulary to talk around it. For example, they may not be able to give the definition of a doctor so instead talk about their experiences of going there or what the doctor wears all the while searching their brains for the right definition. On an IQ test, this would result in a much lower vocabulary score.
