Sir Terry Pratchett: Text and Twitter harming children's development If you have the words to identify exactly what you mean, you can get your message across. I'm sure this is linked to rough behaviour. The author, who has sold more than 65 million books, was supported by Dr Kairen Cullen, an educational psychologist. Dr Cullen said: "New media increases access for lots of children but it doesn't give them the experience of face-to-face contact. We only get good at that with lots of practice. It does not allow children to build up patience and time-keeping. Sir Terry Pratchett, who now suffers from the early stages of Alzheimer's, is said to be the second more-read author in the UK currently and is best known for his work in the fantasy genre.