WAMM

The term “shaping” is what J. B. Skinner called the method of achieving progressive changes of behaviors. It is usually used in positive reinforcement methods of operant conditioning. The term itself brings to mind the creation of a complete picture, one small brush stroke at a time. The analogy to creating a painting is appropriate as to change behavior using shaping as a tool, the whole process is a creative one which works toward the ultimate “picture” of what is desired. In behavior work, we are not dealing with a static object but individuals with minds and behaviors of their own. Shaping is reinforcing behavior that is already occurring so that it will reoccur more frequently.

Shaping uses what Skinner termed successive approximations in the process. This means that the behavior that is progressively closer to the ideal picture in the trainer’s mind is rewarded. For instance, to shape a dog into sitting in a perfect heel position, the steps may be as follows: reward for a sit at the side (which is probably crooked and not close at all) and then each time the dog sits a little closer to the ideal, it is rewarded. It is not rewarded any time that it moves farther out or more crooked than it had been. It is important to remember that in operant conditioning, it is the subject/student who initiates the changes in behavior. There will be periods of trial and error learning. If the undesired behavior is ignored and only the desired/closer approximation to what is desired is rewarded, then the behavior will be then shaped into what is desired.

The successive approximations are also used in a larger context to shape a series of learned behaviors/tasks. These are termed behavior chains. Teaching a behavior chain will not be successful, however, if even one of the components in the chain has not been solidly learned or the behavior of the subject (eg. dog) has not been brought under stimulus control. Dogs who successfully learn behavior chains become multi-tasking individuals such as service dogs, obedience dogs, movie dogs, and search and rescue dogs.

 The secret to behavior chains is teaching the last behavior in the chain first. The subject is rewarded after this behavior and learns to look for the reward after this particular behavior. Then the second to last behavior is taught coupled with the last behavior before the reward. Other behaviors are then added in front of the previously learned behavior until the subject has learned a series of tasks/behaviors before being rewarded.

To illustrate, consider the many behaviors and steps in the retrieve on the flat. In the full exercise, the dog must learn to accept the dumbbell, carry it, relinquish it upon command as well as physically fetch the dumbbell. The dog must also know the finish or return to heel exercise. The steps that I use to teach retrieve on the flat are:

1.      opening the mouth, holding the dumbbell

2.      giving the dumbbell on command

3.      reaching for the dumbbell

4.      picking up the dumbbell off the ground

5.      going to the dumbbell on the ground with handler

6.      going to dumbbell on the ground without handler

7.      returning to handler with dumbbell in mouth

8.      straight sit in front of handler with dumbbell in mouth

9.      holding the dumbbell until commanded to relinquish it while sitting in front of the handler after fetching the dumbbell

10.  returning to heel position

11.  going to get dumbbell on command (handler stays)

12.  waiting in heel position for command to get dumbbell after it was thrown

So once each step has been learned completely, the full behavior chain is put together. The final behavior chain for this exercise from the last behavior to the first is: return to heel, sit in front with dumbbell, returning with dumbbell, retrieving dumbbell, and waiting in heel position for command to retrieve. The end reward is given after the dog has returned to heel position.

The following is Karen Pryor’s Ten Laws of Shaping from “Don’t Shoot the Dog!”. I refer readers to this book for her thorough discussion of each point.

1.      Raise criteria in increments small enough so that the subject always has a realistic chance for reinforcement.

2.      Train one thing at a time; don’t try to shape for two criteria simultaneously.

3.      Always put the current level of response onto a variable schedule of reinforcement before adding or raising criteria.

4.      When introducing a new criterion, temporarily relax the old ones.

5.      Stay ahead of your subject: Plan your shaping programs completely so that if the subject makes sudden progress you are aware of what to reinforce next.

6.      Don’t change trainers in midstream; you can have several trainers per trainee but stick to one shaper per behavior.

7.      If one shaping procedure is not eliciting progress, find another; there are as many ways to get behavior as there are trainers to think them up.

8.      Don’t interrupt a training session gratuitously; that constitutes a punishment.

9.      If behavior deteriorates, “go back to kindergarten”; quickly review the whole shaping process with a series of easy reinforcements.

10.  End each session on a high note, if possible, but in any case quit while you’re ahead.

Teaching requires the educator to first educate themselves. Only by a thorough understanding of the lesson or how to teach what is desired can a teacher be effective. By understanding the “bare bones” basics of learning theory, operant conditioning, positive reinforcement, and shaping, using a conditioned reinforcer, such as a clicker, changes from being a “trick that some trainers use” to a useful tool. The final article in this series will be on “clicker” training.