Pigs lack the skills for referential communication

A new study led by the Eötvös Loránd University (ELTE) in Hungary has investigated whether companion dogs and pigs would show their owners the location of a food reward that is out of reach for them, but accessible to the owners. 

The experts discovered that only if the owners were present in the room, pigs paid them as much attention as dogs did. However, when the reward was also in the room, only dogs tried to direct the attention of the owners to the location of the reward. The findings suggest that directing humans’ attention to relevant locations may not be something that every domestic animal can do.

Referential communication is the act of directing someone’s attention to a specific object in the environment. Humans use this type of communication regularly through language and gestures. Scientists have long pondered whether some species of animals have similar capacities.

“Domestic animals seem especially predisposed to referentially communicate with humans,” said study lead author Paula Pérez Fraga, a doctoral student in the Neuroethology of Communication at ELTE. “However, some human-socialized wild animals can do this as well, thus domestication might not be key for this communicative ability to emerge after all. We noticed that a shared characteristic among these species is that they use many visual signals when communicating with their conspecifics. Could this be a necessary characteristic for animals to engage in referential communication with humans?”

In order to test this hypothesis, the scientists compared the behavior of similarly raised companion dogs and pigs. The animals entered a room where they were either alone with the owner, alone with a hidden food reward, or together with the owner and the reward. While dogs are known to rely heavily upon visual communications, pigs are less visually-oriented creatures.

“We expected an increase of referential communicative behaviors when both the owner and the food reward were present, meaning that the animal was directing the attention of the human to the food location,” said study senior author Attila Andics, an expert in Ethology at ELTE. “We found that when pigs and dogs were alone with their owners, they paid similar attention to her/him. However, after the experimenter hid the reward, only dogs tried to show their owners where it was. Pigs, in contrast, just tried to find the way to take it themselves.”

“We suggest that pigs might lack important characteristics that are crucial for the emergence of this sort of communication. Although we know that dogs are especially skillful in communicating with humans, other animals like horses, cats, and even kangaroos can referentially communicate with us, and all of them rely heavily upon visual communication when interacting with their mates. Pigs, on the contrary, don’t,” Pérez Fraga concluded.

The study is published in the journal Nature Scientific Reports. 

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By Andrei Ionescu, Earth.com Staff Writer

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