We have two apple trees groaning in our front yard, and the neighbor's tree sometimes drops apples into our back yard. As we pick and process the fruit out front, excess or rotten apples get tossed onto the compost pile out back. Extra apples sit on counters, or in our fruit basket. All of which is to say that there are plenty of apples within the reach of a certain dog.
Maya does not touch or seemingly notice these apples. But if I pick an apple and carry it into the back yard, her eyes light up.
This is partly because an apple looks a lot like a B-A-L-L, and a little bit because fresh-picked apples taste best, but mostly it has to do with adding value. Adding/transferring value is one of those things that's useful to think about if you're trying to convince a dog (or other animal) that something is fun or delicious -- it's how we persuade them to enjoy their food more, or love being clipped onto a leash, or prefer to come racing back to you instead of pursuing a squirrel into the forest. Really, transferring value is just another term for dog training.
The big ways to transfer value have to do with classical and operant conditioning, and all that fun stuff. Those are important. But what amuses me are the funny little psychological tricks to make something more amazing.
For instance, most rats find anything forbidden to be incredibly desirable. The more you try to stop them from doing something, the more they want to do it. Obviously, this drives some rat owners totally bonkers (especially those with expensive carpets or accessible electrical cords). But it also means that you can make a very fun game out of pretending something is off-limits, and then getting the ratties more and more excited about trying to get it. Put a box on the floor, for instance, and try to keep all the ratties from going inside. We call this "the Pee Rag game," and, played fairly, it provides tremendous fun for all.
For both the rats and for Maya, my interest in a thing imparts greater value to it. Food in my hand is worth more than food on the ground. If I leave a tissue lying on the couch, a rat will probably make off with it eventually, but if I pick it up, I will attract the interest of all nearby rodents, all of them curious and acquisitive.
This is what is at work with the apples, which are common and boring until I pick one up. Once I've touched it, Maya wants it more than anything, and will eat it all up with tremendous, single-minded enthusiasm.
Besides finding this occasionally useful, I must confess that I find it flattering. Which is funny, of course, because it works both ways. I don't just mean that a sock on the floor interests me much less than a sock dangling from Maya's mouth (though there's that too), but that I spend an inordinate amount of time thinking about what she's doing, and why, and getting all excited about even quite trivial things (like apple eating). I can change Maya's opinion of apples just by picking them, but she changes my view of all kinds of things too.