Why do some mentally ill or mentally retarded people rock forwards and backwards when sitting? I've noticed that they tend to stop rocking in a moving vehicle, but start again at stoplights. This leads me to believe that it's the motion, not the repetitiveness that's important. does it comfort them, and if so, how?

Methos,
As a parent of two children with Autism and ADHD and other issues as well, I am familiar with what you are referring to.

I feel that there is a combination of things occurring during the rocking. My oldest especially has issues with repetitive behavior, he used to tap alot. I noticed that the repetitive behavior correlated with how anxious or stimulated he is. These individuals have a difficult time blocking out too much input and the motion seems to allow them to put into balance their "universe". The repetitive behavior is actually a secondary goal with the movement. It allows their MIND to block some of the overload.

Both of my sons get a lot of pleasure out of driving in a car. It is very soothing and provides an external source of "white 'noise'" and they will often calm down when the car is in motion and get more active and hyper when it is stopped.

This is not "Scientific", I AM an RN, but this is more discerned from my observations of my own (and other) disabled children.

I hope this helps.