It’s amazing to see the powers the cartoon characters have on children. They want to have all their accessories related to these characters. But Thomas the tank engine seems to do much more than entertaining the normal children. It has been found that this blue engine helps the learning process in autistic children. His large eyes and expressive face are credited with helping victims, who often find it hard to read people's faces, to distinguish between different emotions. Parents of autistic children said the combination of clear facial expressions and simple storylines have helped their children make extraordinary progress.

Children on the autistic spectrum do learn a lot from Thomas. The facial expressions are clear and defined which is not always the case with human beings. Thomas was named favourite toy in a survey of 750 parents of autistic youngsters, with Bob the Builder coming a distant second.
Source