What Causes Flapping and Self-Stimulatory Behaviors?
“Self-stimulatory behaviors are common in children with autism as well as those with sensory processing disorders. However, typically-developing children sometimes do these things as well. Just because your child is flapping or doing other self-stimulatory behaviors, it doesn’t mean he has autism. Many people see a child rocking or flapping and they think, “Oh, that child has autism.” That’s not always the case!”
Source: Speech and Language Kids
Great Handout with step by step details on how to intervien with flapping behaviors: stop-flapping-handout
Building Momentum in Schools 