Pitfalls in developmental diagnosis.

I have never seen a paper or chapter of a book devoted to pitfalls and mistakes in developmental diagnosis. This paper is designed to try to fill the gap. It concerns the avoidance of mistakes in developmental diagnosis and is based entirely on mistakes that I have made myself and now learned to try to avoid and on mistakes that I have seen, most of them repeatedly. I have made no mention of mistakes that could theoretically be made but that I have not personally seen. I believe that most assessment errors are due to overconfidence and to the view that developmental diagnosis is easy. Many other mistakes are due to reliance on purely objective tests with consequent omission of a detailed history and physical examination, so that factors that profoundly affect development but are not directly related to the child's mental endowment are not weighed up before an opinion is reached.