If you have ever seen a child rapidly flapping their hands or rocking back and forth, you may have wondered what it means.

One readily noticeable pathognomonic trait of autism is hand-flapping—a stereotyped motor movement that can look a bit like an attempt to accelerating the drying of nail polish. Not all with autism do ...

Most people picture autism as a behavioral condition. Rocking. Repetitive routines. Meltdowns in the grocery store. Those things can be part of the picture, but they tend to show up later. What ...