This is Fred, the Vizsla, learning on lead to detect ovarian cancer. At this point, he stops (does not check the entire rack) when he finds the cancer sample. It's important to reward him, even if he didn't search the entire rack, at this point in training. His thinking is, "well, if I find the cancer, I may as well stop there.... why should I keep looking??" Very soon in his training, however, he will learn to search the ENTIRE rack, which gives the dog higher accuracy rates in SPECIFICITY. For beginners, it's important to reward the small achievements along the way, incrementally demanding more of the dog as he advances. Good job, Fred!!