There are many different ways to teach the competition Scent Discrimination exercise. How I do this is a combination of free shaping and chaining.
Behaviors needed: Retrieve on a verbal cue.
I check that the dog has no problem picking up the articles (metal and leather). I don’t spend much time on this, as I don’t want a strong article retrieve — yet! The dog needs to learn to locate my scent first. I do just enough to know that they retrieve them without a problem.
Touch Center of Scented Article
I scent this first article with just my hands (no food is placed on the article, except whatever treat scent happens to be on my hands). I place the article on the floor and C&T nose touches to the center bar. For avid retrievers, I hold the article until I have consistent, closed mouth touches and then move to the floor.
What behavior I want before moving on:
- Consistent closed mouth nose touches to the center bar, with both leather and metal articles.
Add Additional Articles
This is where the dog begins to associate my scent with the C&T.
Scent one metal or leather article (I consistently use the same number throughout). Have someone else touch another article (if no one is home, I use some dirty laundry and scent the other articles with that, using the opposite hand that I use to scent my article).
Now I place my scented and the other article on the floor fairly close together, clicking when the dogs’ nose touches my scented one. I toss the treat away, the dog comes back, nose touches and C&T again for touching my scented one. Repeat. Add another article (I mix the leather and metal ones right from the start). I build up to 5 total articles, 2 leather, 2 metal and my scented one. I arrange them in a straight line.
Vary Location of Scented Article
When the dog is off eating the tossed treat, I start to place my scented ones in a different spot in relation to
the others each repetition. I use tongs to move the “unscented” article and my hand to move my scented article. I avoid placing an unscented one in the place my scented one was previously, to avoid any residual scent adding any confusion.
(The first dog I taught scent discrimination this way taught me to do this, she scented around the articles, looked at me and then indicated with a nose touch the floor where a scented article had previously been and the upper corner of the end of all the “unscented” articles where I had held them with just two fingers while putting them down!)
I do quite a few sessions at this level, doing them in different locations of my house. I vary my straight line arrangement, sometimes horizontal and sometimes vertical or diagonal. Only the dog knows how many repetitions will be needed for them to figure out that only the one that has your strong scent on it is the one that is clicked and treated.
The behaviors I am watching for before moving on:
- I delay the click slightly and see that the dog expect to be clicked when she touches the scented one (might start, or look at me or…what does your dog do when they expect to be clicked?)
- When the click is slightly delayed, they go on to another article and immediately go back to the scented one.
- The dog skips nose touching the “unscented” articles, no longer relying on whether or not she is clicked to decide if it is that is not the one.
- The dog clearly is using his nose, passing it over the unscented ones (thats not it) and only nose touching my scented one.
Teach My Scent is the Cue to Retrieve
Now that the dog is reliable at locating my scented article I add the retrieve cue.
Reduce the number of articles so that there are just 2, your scented article and one other. Space them farther apart so it is less likely that the dog will move on to the other article before you can get the verbal cue out. When the dogs nose is above the correct article, just before they will nose touch it, give your verbal retrieve cue. When the dog picks up the article, C&T. Yes, they most likely will drop the article — that’s ok at this point, we want to let them know that now, picking it up that one is what we want!
I gradually add a few more articles and repeat this with both metal and leather. Keep them spread out enough that it is easy to give the cue. After a number of repetitions, the dog will start to anticipate. You should see them start to open their mouth as they smell your scented article. Yay! When the dog is reliably picking up the correct article without the verbal retrieve cue, I stop clicking the pick up and instead cue front when they pick up the article. They quickly learn to anticpate that too, and then that can be dropped.
Still More to Do!
Now we have the basic behaviors in place, the dog goes to the articles, locates your scented one, picks it up and sits in front. Now I gradually start adding more articles and changing the arrangement, I make the straight line of articles not so straight or put them in a square or circle. Go slowly with this, it can’t be too reliable and your dog needs time to learn to check all of them. I only increase the number or change to a more challenging arrangement when the dog is 100% correct at the previous level. Ok…wait…what? What about the 80% rule?
The 80% Rule
This is a general guideline used to decide when to increase criteria. The purpose and reason for raising criteria when it is reliable 80% of the time is because that level of reliablility will be strong enough that the behavior won’t decline too much when made more difficult (the dog easily quits), but it is not so strong that it becomes too difficult to change it (the dog persists in doing the previous criteria). It is a very useful guideline (it isn’t exact, around 80% is good). However, we are now at a level where we aren’t going to change the behavior. Picking up our scented article and coming in to sit in front is not going to change. This I want to be as close to 100% as I can get it!!
So I continue to gradually add more articles and change the arrangement and location of the scented one. Whenever an element is added that is more difficult — distractions, distance, new location, I reduce the number of articles and/or distance from them.
Signs that it is too difficult and that you might be moving too fast:
- The dog is going around the articles, but their mouth is not closed, they aren’t using their nose.
- The dog picks up and puts down “unscented” articles.
- The dog goes out to the area of the articles but looks off towards other things before starting
- The dog just grabs one
What if the Dog Brings Back the Wrong Article?
I don’t change what I am doing, the dog comes to front and I take the article. I don’t give a treat or cue them to finish, just set up and do another repetition. I avoid doing anything because the dog might start to look to me to verify they are correct and drop the correct article if they don’t get that verification. So no helping them, no pointing it out or bringing them to the correct one. It can be hard to not give some indication with your facical expressions. I try to remember that I don’t know what the dog smelled, the scent could have drifted so that they did indeed smell the scent when they reached that article. Or they just made a mistake. If it happens more than once, than I need to change something so the dog will be right.