Where did the idea come from?
The original research that pointed medicine in the direction of believing there were two distinct types of autism came from a paper written in 1943. Leo Kanner was a practicing child psychiatrist who was trying to make a name for himself. He conducted a study of 11 children who had unusual symptoms. He wrote a paper on this study and quickly made his mark. He described these children as having a new developmental syndrome which he called early infantile autism. He described two types of the disorder being innate and regression.