She's a doggy genius!
It took Lyra about a week to grasp the basics of scent discrimination. This video shows the steps I took her through:
Take the food out of the tins as soon as possible - two days in Lyra's case. The reason for the food is to get her using her nose; then I moved to shaping the rest of the picture.
Note that she retrieves the articles to me. This step is definitely optional. I allowed it because she did it naturally after a day or two, and it does make it very clear that she understands her job. With most dogs, I'd accept any hard nosing on the object, and I'd add a retrieve down the road.
Now that she is comfortably finding my scent, I will focus on generalizing the behavior. I'll ask her to play this scent game with many different objects made out of different materials. Marker pens, clothespins, canning rings, real articles, leather strips, plastic toys, etc. I'll also take her into more distracting environments, but not for awhile. Right now I work anywhere from five to fifteen objects; at some point I will increase that to any number I might wish. I may also play the game with her toys.
Her "correction" for making a mistake is that I refuse to take the object from her; I simply stare at the pile.
So, is Lyra a doggy genius? Maybe, but probably not. Puppy Ziva started articles a week after Lyra. She also mastered the concept in one week - working 10 cans with no food in them. It seems that the category of creature called "puppies" are really quite smart.
Here's Ziva. Note her mom's overwhelming enthusiasm for Ziva's success. Good on mom! Someday the cookies will be gone and their relationship needs to get them into the ring.