I wonder if there is such a thing as UI designer/doggie factors engineer? We picked up two types of dog beds from Petsmart: one that is a simple pad and another that had a fringe around it. Ninja knew the unfringed pad was a bed, but she didn't quite know how to lay on it -- sometimes she would rest her chin on it, other times she would lay across a corner. Less often she would lay in the middle of the mat. We brought out the fringed mat from her crate and she immediately curled up in a ball in the center. Perhaps it Don Norman could update Design of Everyday Things with a chapter on doggie beds.