One of the "psychologically based" elements that can come along with RS is hyperactivity and impulsivity. Up until Abby was about three and a half we saw no signs of this. Obviously this has changed. She is now quite hyperactive and has a great deal of significant impulsivity.
When people hear you talk about your child being impulsive they almost always chime in with "so it my son/daughter". I would say that at least 75% of the time this is the response. I have taken to smiling and nodding instead of correcting because it keeps my blood pressure down. People truly do not understand what true clinical impulsivity looks like.
Here is what impulsivity is NOT: Running with a stick in your hand, jumping on the bed, running away from your mother/father in the store or being generally wild.
What impulsivity DOES look like it more like this: Jumping from the top of the slide ladder and crying because you didn't mean to do it (ie: didn't think about the consequences). touching the hot stove YOU KNOW IS HOT because you couldn't control yourself. Smacking someone behind you in line at the store and then feeling mortified that you did. Washing your hands (because you have an obsession with washing your hands) and once you're all done touching the bottom of the sink and starting over (did this several times this week ;D). And on and on and on.
It such a source of frustration for parents of kids with ADHD, ADD, Asberger's, Autism, SPD and so many other disorders that come part and parcel with impulsivity and hyperactivity when every mother and father makes a point of stating that their (very obviously typical) kid has the same issues. I guess if we could just walk a mile in someone else's shoes...