Monday, January 12, 2009

Clicker training


Clicker training is the process of training an animal using a conditioned reinforcer, which indicates to the animal ("marks") the precise behavior that was correct. It was originally discovered and used with laboratory rats, and later was used in training animals such as dolphins and pigeons. It is a technology derived from the study of operant conditioning in behavior analysis. The name "clicker training" is used because the primary tool is a small mechanical noisemaker called a clicker. Clicker training has also been successfully used in the training of a huge variety of species including many marine animals, livestock, household companion animals, equines, etc. It is used in the training of service animals, police K-9's, search and rescue animals, animals used in military activities, and many more. Even common house cats are easily trained using clickers and treats.

Advantages

One of the challenges in training an animal is communicating exactly when the animal has done the behavior that the trainer is attempting to reinforce. As a simple example, consider teaching a dog to back up. At the instant that the dog moves backwards, the trainer must let the dog know that it has done the correct thing. However, the traditional "good dog!" takes so long to say that the dog might already have moved on to some other behavior. By the time the dog realizes it is being praised, it might be moving forward again, or even sitting and scratching.

Besides the imprecision in timing, using the trainer's voice for information means that the actual signal will vary. The trainer's voice, pronunciation, tone, loudness, and emphasis can change even during the same training session, and training is slowed when the animal has to realize that some variations (loudness or enthusiasm) aren't important while others ("good dog" vs. "bad dog") are.

A conditioned reinforcer solves these problems. The conditioned reinforcer can be any signal that the animal can perceive, so long as the signal is brief (to prevent the problem of imprecise timing) and consistent (to prevent the problem of variations that may confuse the animal). Dogs and horses are often trained with a clicker or cricket, a small metal tab that makes a "click" sound when pressed and released. For dolphins, the conditioned reinforcer is usually a whistle. However, not all conditioned reinforcers are sounds. Goldfish can be trained using a quick flash of a flashlight as their "clicker". Deaf dogs can be trained with a vibrating collar.

Disadvantages

There are a few commonly perceived drawbacks to clicker training. One is a reliance on the clicker to signal the dog; however, in practice the clicker is used primarily to teach new behaviors, or fine-tune precise ones, and its use is not required (or desirable) past that stage. For those odd times when the dog offers a desired behavior and the clicker is not handy, something as simple as a tongue-cluck can be used; it is less precise than a clicker, but will still mark the event.

Another perceived disadvantage is that dogs will be confused in group settings, and unable to discern which clicker is "theirs". Hundreds of group clicker classes each year have proven this to be an unnecessary worry. There are some situations where a clicker may not be loud enough, such as in hunting or retrieving when the dog is "working away" from the handler; there are also some dogs who are sensitive to noise and frightened by a clicker. In these situations an alternative event marker, such as a whistle for "away" training or a retractable pen or pocket stapler for noise sensitivity, can work just as well. Also, as clicker training has progressed, so have clickers, and there are now devices available which overcome many of these concerns.

The first step in clicker training is to teach the animal that the clicker sound means that they will get a reward. To do this, the trainer does what is called "charging" or "loading" the clicker. The trainer clicks the clicker and simultaneously or immediately thereafter gives the animal a reward, usually an unaccustomed, tasty treat, one small enough to be consumed almost instantly. (Some trainers substitute play with a favorite toy. However, this practice can interfere with the goal of maintaining a high rate of reinforcement.) The trainer performs up to 20 repetitions per session.

Some animals tend to learn the association much more quickly than others. Dogs, for example, often learn the association in one session, with as few as five to 10 repetitions. Progress may be tested by waiting until the dog's attention is elsewhere and then clicking. If the dog immediately looks toward the trainer as though expecting a reward, it is likely that the dog has made the association.

After that, the trainer can use the clicker to mark desired behaviors. At the exact instant the animal performs the desired behavior, the trainer clicks and promptly rewards. One key to clicker training is the trainer's timing; clicking slightly too early or too late rewards and therefore may reinforce whatever behavior is occurring at that instant. Another is to create opportunities for the animal to earn rewards very frequently. A reinforcement rate of one click/treat (C/T) every two to three seconds is common among professional dog trainers. Finally it is often necessary to break down even simple tasks into smaller sub-tasks or to start with easy-to-meet criteria which are gradually tightened.

Help with clicker training



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