The Impact of Training Method on Odor Learning and Generalization in Dogs (Canis lupus familiaris)

Detection dogs are required to learn and alert to multiple different odors during training and to generalize this learning to similar odors when working. They should be both sensitive to variation in the target odors and specific enough to avoid false alerts, but how readily they achieve this is likely to depend on the training method employed. The majority of agencies train by presenting single target odors in isolation, and adding additional odors consecutively, although recent research with rats suggests intermixing the target odors concurrently throughout training may be a more effective approach. This study therefore tested the relative efficacy of intermixed training in dogs. Using an odor-detection lineup, pet dogs were trained to detect two target odors, A and B. Those allocated to the "sequential" group were trained to criterion on odor A and then trained on odor B (or vice versa), the "compound" group were trained on a mixture of AB, and the "intermixed" group trained on A and B concurrently. Each dog was then tested on all combinations of the test stimuli (A, B, and AB), as well as combinations containing a novel interferent (AC, BC, and ABC). Results revealed that dogs trained by the intermixed method made significantly more correct (true positive) indications, and significantly fewer miss (false negative) indications than the other two methods, suggesting that intermixed training is more effective than currently used alternative training methods. Thus, for improved performance and generalization, we recommend detection dog training should use an intermixed method of training.