Specific dog breeds, such as border collies, can learn the verbal names of their favorite toys, but what goes on in the dog’s mind when told to get a certain toy? According to a recent article published in the journal Animal Cognition, these dogs store important sensory characteristics of their toys — specifically, how they look and smell — and recall those characteristics when looking for the said toy.
“If we can understand what senses dogs use when looking for toys, it could reveal how they feel about them,” said study co-author Shany Dror, a biologist at Eotvos Lorand University in Budapest, Hungary. “When dogs use sense of smell or sight when searching for a toy, it indicates that they know what that toy smells or looks like.”
Previous studies suggested that dogs typically rely on sight, or a combination of sight and smell, to locate target objects. Few dogs can also identify objects based on verbal labels, which the authors refer to as “gifted word learners” (GWL) dogs. “Like humans, GWL dogs not only recognize the labeled objects — or categories of objects — as stimuli they have already encountered, but they also identify them among other similarly known named objects, based on their verbal labels,” the authors wrote. They wanted to investigate whether GWL dogs have an improved ability to distinguish and/or recognize objects compared to typical dogs.
To find out, they conducted two separate experiments. The first involved 14 dogs, including three GWL dogs (all border collies): Max, Gaia and Nalani. All three had participated in previous studies and showed that they knew the names of more than 20 dog toys. Most dogs were tested in the lab; three were tested at their homes with the same experimental set-up. The researcher and the dog’s owner were in the same room with the dog. An adjoining room contained dog toys. The rooms were connected by a corridor and separated by heavy curtains. All windows were covered with dark nylon sheets.
The same 10 unknown dog toys were used on all dogs and the toys had different shapes, sizes, colors and materials. The researcher randomly divided the toy into two sets and then randomly chose one toy from each set to be the target toy. The other four toys in each set were “distracting objects.” The owner would then play with their dog using a target toy, sometimes placing it with the other toys and ordering 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 both light and dark conditions with the hallway and toy room lights off. They were asked 10 times to pick the target toy from the other four toys in a set, which were scattered randomly on the floor. The toy was reshuffled between each iteration. Everything was captured with an infrared video camera, and the researchers recorded not only the selection and retrieval of toys, but also the searching and sniffing behaviour.
The second experimental setup and location were the same as the first, but only the three GWL dogs were tested, along with an additional GWL dog named Whiskey. All four knew the names of the 20 toys used in the experiment, scattered randomly on the floor. This posed a more complex case of object recognition; the dogs could not simply rely on familiarity with the toy to successfully retrieve the target toy. Each owner ordered his dog to pick up a particular toy by giving it a name. If the dog found the right toy, it was rewarded. Again, the dogs were tested in both light and dark conditions.
All dogs in the first experiment — regardless of whether they were GWL dogs or typical dogs — successfully chose the target toy in both light and dark conditions, although it took longer to find the toy in the dark. Most relied on visual cues, although dogs have an excellent sense of smell. However, the dogs sniffed more often and longer when searching for the toy in the dark. The GWL dogs in the second experiment were also able to select said toys when commanded by their owners, with similar reliance on visual cues – what the toy looks like – complemented by their sense of smell (what the toy smells like) , especially in dark conditions.
According to the authors, this confirms that when dogs play with toys, they absorb their features using multiple senses, creating a “multi-storey mental picture.” They prefer to rely primarily on visual cues, but dogs can pick up on other sensory cues, especially smell, when circumstances call for it.
In short, “Dogs spontaneously encode different features of the objects, leading to the construction of multisensory mental representations,” the authors concluded. “In the case of GWL dogs, a memory of the multisensory representation is evoked by hearing the verbal labels of the objects as they perform complex object recognition tasks.”
DOI: Animal Cognition, 2022. 10.1007/s10071-022-01639-z (About DOIs).
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