Child myths Jean Mercer When I started this blog, it was my plan to spend a lot of time talking about “child myths”— common beliefs about child development that do not turn out to be supported by research evidence. This was what I had done in my book “Child Development: Myths and Misunderstandings” (Sage, 2009), where I commented on 51 beliefs that turn out to be largely mythical— the “urban legends” of the child development field. The myth in question is the idea that all parts of human brain development show a high level of plasticity, or guidance by environmental events. However, there are a number of facts about brain development that are ignored by people who assume that all brain functions and structures have high plasticity and can be shaped by environmental stimulation. One important issue is that different parts of the brain actually have different developmental mechanisms; for some, plasticity is high, for others, it is low.