The click is clear
The click means one thing only: "Bingo. You win."
It's like when you're waiting for a special call and you hear the phone ring. It's not the reward itself; it's just the clear-cut, simple message: "You got it."
The click is more than just a conditioned reinforcer. It's what engineers call feedback. It marks or identifies precisely which behavior is paying off and should be done again. That's why we call it a marker. (FYI, this use of the word "marker" is not a clicker training invention; the phrase "event marker" was first coined by Skinner's protégé, the late Ogden Lindsley, when he used a sound to teach his pet donkey to open a mailbox.)
The voice is a wonderful tool for conveying the trainer's pleasure and pride, and for giving warnings, instructions, and cues—and we use it for all those purposes. But because it has all these functions, the voice does not make a very good marker. The brain must parse out all that other information.
The result seems to be that "clicker is quicker." We know this from practical experience. For example, the complaint I heard many times in the early days of clicker training's growth in the dog world was this:
"I converted all my classes to clicker training, and now my students are going through my six-week curriculum in four weeks."
That gave the teacher a new problem—how to keep the students busy during the extra two weeks they'd paid for!
But is this difference in speed of learning real? And, if so, is it due just to the click? Psychologist and clicker trainer Lindsay Wood decided to take a look at the question experimentally. She trained a number of naive shelter dogs to cross the room and bump a target, using the click as a marker, and taught another group of dogs to perform the same behavior using the word "yes" as a marker. Same trainer, same skills, similar clueless dogs, but the clicker dogs learned the behavior roughly 40% faster.
And Lindsay teased out another very interesting piece of information—the clicker only made that difference during the learning phase. The word "yes" was as good as a click for maintaining the behavior once the dog already knew what to do. It was only when the dog was trying to figure out what worked that the click displayed its power.
With the author's permission, we've posted Lindsay Wood's master's thesis on our website so you can see just how the experiment was set up and go over the data for yourself.
The next big question, of course, is WHY the difference occurs. That's due to how reinforcers are processed in the brain. Neuroscientists know something about that, and I'm reporting on it in my upcoming book, Reaching the Animal Mind. The manuscript has at last gone to press and will be in bookstores in June of 2009.