During my 15 years of work with persons that have severe cognitive understanding, I have searched for the ultimate cause/effect device. I created it with the CooperCar, but WakerShaker is a close second. It is is far more convenient (5" tall and 2" wide), not to mention, far less expensive. Do not take WakerShaker lightly. Yes, it's a simple switch modified massager (vibration device), but you simply will not get better, quicker results about what a switch can do. That, after all, is what you're trying to teach with cause/effect training. Besides, WakerShaker is fun! If you are working with a person that needs to understand the power of a switch, you need WakerShaker.