The understanding of childhood autism has benefited dramatically from the application of theories and methods developed in studying normal children. The classic studies carried out by Hermelin and O'Connor (1970) provided a model for this approach. In the 1980s there has been a flowering of empirical research carried out primarily in Great Britain and the United States on the psychological characteristics of autistic children. The investigators of this research were trained in a variety of disciplines including psychology, linguistics, and psychiatry but share knowledge and appreciation for the discipline of normal child development.