The olfactory capability of dogs to discriminate between different quantities of food

A previous study failed to find evidence that dogs could use olfactory cues to discriminate between 1 and 5 hot dog slices presented on a single trial (Horowitz et al., Learning and Motivation, 44, 207–217, 2013 ). In the experiments reported here, multiple trials were used to test dogs’ ability to use olfaction to choose one of two opaque containers under which a larger number of food items was placed. In Experiment 1 , dogs chose between 1 and 5 hot dog slices. In Experiments 2 and 3 , we examined dogs’ ability to discriminate between numbers of hot dog slices that varied in the numerical distance and the ratio between the smaller and larger quantities. Experiment 4 explored olfactory discrimination between quantities of a different food, dog kibble. Experiments 1 – 3 all showed that dogs used olfactory stimuli to choose the larger number of hot dog slices, but Experiments 2 and 3 revealed no effects of distance or ratio between numerical quantities. In Experiment 4 , dogs failed to discriminate between 1 and 5 pieces of dog kibble. Factors that allow dogs to use olfactory cues to discriminate between quantities are discussed.