Master of Science
Although some animals, such as elephants, can use olfaction to discriminate quantities of food, previous research suggested dogs cannot smell the difference between quantities of hot dog slices. In the experiments reported here, dogs were allowed to smell two opaque containers under which were placed different numbers of hot dog slices, and then were allowed to make a choice between containers. In Experiment 1, dogs chose between one and five hot dog slices and chose the larger quantity at an above chance level. In Experiment 2 and Experiment 3, I tested whether dogs conformed to the distance effect and/or the ratio effect when smelling quantities and found no evidence of either effect. In a fourth experiment, I tested whether the type of food used influenced the performance of dogs and found that the performance of dogs was higher when hot dog slices were used as reinforcement rather than kibble pieces. In the fifth experiment, I tested whether dogs could hear the difference between quantities of hot dog slices and found no evidence of quantity discrimination in this modality. These results suggest that dogs are capable of using olfaction to discriminate quantities of food based on amount, but not number, of hot dog slices.
Summary for Lay Audience
I wanted to replicate an experiment in which it was found that dogs could not locate a larger quantity of hot dog slices by scent when visual information was hidden. When I replicated this study with more trials per dog, I found that dogs were able to find the larger quantity above chance level. In my second experiment, I tested if dogs were better at discriminating quantities that were farther apart in number or at lower ratios (when the small quantity is divided by the large quantity). Because I found no evidence for either effect in my second experiment, my third experiment replicated my second experiment but used wider number distances and ratio differences in order to increase the saliency of these differences. Again, I found no evidence for either effect. In my fourth experiment, I tested if dogs find the larger quantity better when certain food types are used. I found that dogs found the larger quantity more often when tested with hot dog slices as compared to kibble pieces. In my fifth experiment, I tested whether dogs could hear the difference between quantities of hot dog slices when a container was shaken. Because dogs performed above chance on the odor control condition that I used in this experiment, I could not conclude that dogs were able to discriminate quantities in this modality.
Jackson, Shayla, "The olfactory and auditory capabilities of dogs (Canis lupus familiaris) for locating different quantities of food" (2020). Electronic Thesis and Dissertation Repository. 7243.
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