I've noticed with my son, who sometimes walks and runs and at others uses a wheelchair, that when he is ambulatory I see one type of self-stim movement. and when he is not I see another. And when he is using the wheelchair and feels happy or excited he really goes to town with the rocking, twisting, arm flapping, head side to side. I do not see these behaviours when he is free to move around using his legs. I also don't see them when he is unhappy or bored. Though, he DOES have other self-stim behaviours when he is unoccupied or having trouble with sensory integration issues.