I totally buy it. My girl is in a vision cage (sliding glass doors) and before I had a lock, she would jam herself in the track for the glass.... and start inching and inching her belly scales. She was not yet strong enough to move the glass, but I promptly ordered a lock. She has SO learned that the glass slides and was working out how to slide it. When I installed the lock, she spent two days running her tongue all around it. She knew it was going to be a foil in her plan.

I think they can figure out far more than we give them credit for.