I took this picture some time ago , when the dog was even smaller than she is now & I was wondering how she perceives the world . These trees look big to me but they must look enormous to her .I don't think its silly to talk about perception and concept forming in animals . The dog clearly has categories of people she recognises as "friends " and friends of different types as well . for instance she knows those who bring her gifts , those who don't and those she mustn't greet with her usual spittle laden ,wriggly madness . So to my mind there mus be some categorisation and the beginning of the concept "friend" .I wouldn't like to guess what that concept is in dog language . but there are definite reactions for disparate groups that importantly she has not been trained to do. These are categories that have been set by the dog due to some cues that I do not recognise. I think that implies at the least, behaviourist learning. As an aside ,a definite example of behaviourist learning, is that she has learnt that if she brings in a pebble from our garden , and tosses it around, I will give her a biscuit to drop it before something gets smashed. There are now less and less pebbles in the garden, as I seemed to have trained her to "fetch" pebbles