Ask a question. If your subject answers, they’re a moron at worst. If they don’t answer, you might have an idiot on your hands. [...] To classify [IQ] scores below 70, psychologists invented a nomenclature of retardation. Those with IQs between 51 and 70 were called morons. Morons had adequate learning skills to complete menial tasks and communicate. Imbeciles, with IQs between 26 and 50, never progressed past a mental age of about six. And the lowest of all were the idiots, with IQ between 0 and 25, who were characterized by poor motor skills, extremely limited communication, and little response to stimulus.
Not politicaly correct in educational terms any longer EoR will, however, need to be more careful identifying various 'therapists' and other true believers. For a start, antivaccination proselytisers and creationists (amongst others) would seem to qualify as technical idiots since they repeat the same statements over and over (echolalia) and show no response to stimulus such as scientific evidence at all.