Study sheds light on how dogs recognize their favorite toys

[embedded content] Dogs form a "multi-pattern mental image" of their toys, a new study has found.

Specific dog breeds, like border collies, can learn the verbal names of their favorite toys, but what goes through a dog's head when told to fetch a given toy? According to a recent paper published in the journal Animal Cognition, these dogs store key sensory characteristics of their toys, including their appearance and smell, and remember these characteristics when they search for the named toy.

"If we can understand what senses dogs use when searching for a toy, it may reveal what they think about it," said co-author Shany Dror, a biologist at Eotvos Lorand University in Budapest, in Hungary. "When dogs use olfaction or sight when looking for a toy, it indicates that they know what that toy looks like."

Previous studies have suggested that dogs generally rely on vision, or a combination of sight and smell, to locate target objects. Few dogs can also identify objects based on verbal tags, which the authors call "good at learning words" (GWL) dogs. "Like humans, GWL dogs not only recognize labeled objects - or categories of objects - as stimuli they have encountered before, but they also identify them among other similar named objects, based on their verbal labels," the authors wrote. They wanted to determine if GWL dogs had a better ability to discriminate and/or recognize objects compared to typical dogs.

To find out, they conducted two separate experiments. The first involved 14 dogs, three of which were GWL dogs (all border collies): Max, Gaia and Nalani. All three had participated in previous studies and demonstrated that they knew the names of more than 20 dog toys. Most dogs have been lab tested; three were tested at home using the same experimental setup. The experimenter and dog owner stood with the dog in a room. An adjacent room held dog toys. The rooms were connected by a hallway and separated by heavy curtains. All windows were covered with dark nylon sheets.

Enlarge / This very good boy named Max is happily posing with a collection of toys. Photo of cooper

The same 10 unknown dog toys were used with all of the dogs, and the toys came in different shapes, sizes, colors, and materials. The experimenter randomly divided the toys into two sets and then randomly selected one toy from each set to be the target toy. The other four toys in each set were "distractor objects". The owner then played with his dog using a target toy, sometimes placing it with the other toys and commanding the dog to retrieve it. When the dog successfully retrieved the target toy, the dog received a reward.

After the training phase, each dog was tested in light and dark conditions with the hallway and toy room lights turned off. They were asked 10 times to retrieve the target toy from among four other toys in a set, which had been randomly scattered on the floor. The toys were reshuffled between each iteration. Everything was recorded using an infrared video camera, and researchers recorded not only toy selection and retrieval, but also seeking and sniffing behavior.

The second experimental setup and location were the same as the first, but only the three GWL dogs were tested, plus an additional GWL dog named Whisky. All four knew the names of the 20 toys used in the experiment, scattered randomly on the floor. This was a more complex case of object recognition; dogs could not simply rely on familiarity with toys to successfully retrieve the target toy. Each owner ordered their dog to retrieve a...