hii,
Very often, I see trainers training the dog to do nose work - indication and search for the scent. When the dog have the positive indication with the box, the trainer would secretly pop his reward* (usually taken from trainer's back or side pocket; and most importantly not letting the dog where the reward came from). Thus the so-called unknowingly dog will be so surprise that the reward just pop because of his positive finding. It works, it almost always able to motivate the dog to continue the training. Trainer wanted the dog to believe that the dog found his toy.
