The Impact of Training Method on Odour Learning and Generalisation in Dogs (Canis lupis familiaris)

Detection dogs are required to learn and alert to multiple different odours during training, and to generalise this learning to similar odours when working. They should be both sensitive to variation in the target odours 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 odours in isolation, and adding additional odours consecutively, although recent research with rats suggests intermixing the target odours concurrently throughout training may be a more effective approach. This study therefore tested the relative efficacy of intermixed training in dogs. Using an odour-detection line-up, pet dogs were trained to detect two target odours, A and B. Those allocated to the ‘sequential’ group were trained to criterion on odour A and then trained on odour 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, 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 generalisation, we recommend detection dog training should use an intermixed method of training.