I too, think they understand way more than we give them credit for. Yogi will be frantically searching for his current favorite toy. I'll tell him he left it in the bedroom. He'll turn, run to the bedroom and come back with it.
Gracie Ruth has the Selective Hearing disability. There are times I'll call and call for her and nothing. But as soon as she hears, Gracie Ruth Murray! she comes running and has the good sense to just her i'masweetpuppydon'thurtme look on me.