This entry grew from a discussion on one of the clicker training mailing lists I frequent. The subject was whether one can lure and shape at the same time, or if they were two separate (and exclusive) techniques.
Shaping is “successive approximation.”
Usually when shaping is discussed, people associate it with an entire behavior taught through successive approximation, start to finish. For example, to shape a spin, you might first click for a glance to the right. Then a slight head turn. Then a weight shift. And so on until you have the complete spin.
Shaping can also be used to teach just certain parts of a behavior. For example, say you taught a sit through luring. Now you’re ready to add duration. First one second. Then two. Then four. That’s using shaping to add duration.
Shaping — successive approximation — *can* be combined with other methods, however. Let’s look in detail at a specific example: a fold-back down.
The trainer places the treat between Dog A’s front paws. He ducks his head down and back to get it, and within a moment, drops his entire body. Click! That’s NOT shaping. That’s pure luring. The lure was used to get the *complete* behavior.
The trainer places the treat between Dog B’s front paws. He ducks his head down and back to get it, but unlike Dog A, he doesn’t drop his entire body.
There was a dog like this in River’s class this week. These were not clicker trainers, and they could not get the dog to down. I had to chew on my fist to keep from interrupting. Not my class, not my class, not my class….
So the trainer MIXES luring and shaping: She puts the treat between his front paws. He ducks his head down and back — click and reinforce. Next rep he shifts his weight back — click and reinforce. Next rep she waits for the elbows to bend — click and reinforce. And so on. Each time she lured, but also she worked with successive approximations.
It’s precisely because successive approximation can be used in so many varied ways that I prefer to use the term “free-shaping” when talking about starting a behavior from the beginning and “shaping” when I’m referring to other uses of successive approximation.