Pigs Can Game, Scientists Discover

Four pigs were trained to use joysticks to play a simple video game, and some excelled, revealing the impressive intelligence of pigs.
February 11, 2021, 2:00pm
​Image: Eston Martz/ Pennsylvania State University
Image: Eston Martz/ Pennsylvania State University
ABSTRACT breaks down mind-bending scientific research, new discoveries, and major breakthroughs.

Pigs are famously smart: they can use tools, learn how mirrors work, and display sensitivity to the emotions of their peers. 

Now, scientists have confirmed that pigs can acquire another skill that requires impressive cognition and dexterity: gaming. 

Four pigs showed a “remarkable” ability to play a joystick-operated video game, an indication of “their behavioral and cognitive flexibility,” according to a study published on Thursday in Frontiers in Psychology.

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Though the game was originally developed by NASA to test monkeys, the pigs were able to learn how to accomplish most of its objectives without the benefits of opposable thumbs or keen eyesight. 

“There are lots of other examples, scientifically, where pigs have shown they're capable of some pretty interesting learning,” said lead author Candace Croney, a professor at Purdue University and director of the Purdue Center for Animal Welfare Science, in a call. “But this kind of computerized interface was really different.”

Allow me to introduce the players: a pair of Yorkshire pigs named Hamlet and Omelet, and a duo of Panepinto micro pigs named Ebony and Ivory. Each pig was trained to toggle a joystick using their snouts in an indoor facility at Pennsylvania State University. 

Once they mastered that skill, the pigs started gaming once a day for a period of 12 weeks. Hamlet and Omelet had to stop at that point because “they had grown too large to stand long enough to complete sessions, and also no longer fit within the constraints of the test pen” according to the study, which was co-authored by Sarah T. Boysen, a chimpanzee expert at Ohio State University.

The first “level” the pigs had to pass displayed a blue border running along all four sides of a screen located right behind the joystick. The goal was to use the joystick to move a cursor on screen so that it intersected with any of the four walls. The next level displayed a border with only three walls; the pigs were again tasked with hitting one of those three lines. If they hit the empty side of the screen, it would be counted as an error.

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The game continued to increase in difficulty, showing just two walls and then one, which were arbitrarily generated on different sides of the screen. This upped the odds that the pigs would log an error by moving the cursor to a borderless part of the screen. Even so, all of the pigs still performed well on the challenging one-wall targets, moving the cursor the right way at a rate above random chance.

Things got dicier in the following levels, when the wall borders became smaller and even began to move around. Though some of the pigs were able to perform well with the shrinking walls, the moving targets proved too much for their snout-joystick coordination.

“You have to move the cursor, not just to hit a very small target, but a moving target,” Croney explained. “That's dexterity. Our pigs never got to that phase.” 

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Candace Croney and one of the Yorkshire study pigs, Omelet. Image: Eston Martz / Pennsylvania State University

Given that all of the pigs were found to be far-sighted, and this is a test designed for dexterous animals such as monkeys or rats, it is noteworthy that these porcine players were able to make it as far as they did. 

Just like human gamers, each pig had its own individual aptitude for the tasks; Ivory emerged as the “little star pupil,” Croney said, as he set a record of hitting the one-walled targets 76 percent of the time. In fact, Ebony and Ivory were even able to pick up the game again a year later when they had moved with Croney to another facility, hinting at sophisticated long-term memory. 

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“It’s like any kind of learning: you're going to get variation from individual to individual in terms of what they can learn, how quickly they can learn, how well they perform tasks, and how consistently they perform,” she noted. “That was really a fun thing to see. It felt like a classroom. You just had to know something about who you were teaching in order to get the best work out of them.”

On that note, the study also offered a window into the social bonds that these animals forge with their trainers and caretakers. Croney served both roles for the pigs in these experiments, and the animals relied on her encouragement to motivate them to complete the games. 

For instance, the pigs were normally rewarded by an automatic treat dispenser when they played the game well, but when the dispenser broke, they “continued to make correct responses when rewarded only with verbal and tactile reinforcement” by Croney, the study said. In other words, kind words and nice pets from their trusted caretaker resulted in better outcomes in the game.

While this reveals a very endearing side to pigs, the downside was that the animals often phoned it in if Croney wasn’t personally there to cheer them on.

“I remember coming in on one occasion when I had walking pneumonia because something needed to happen that day, and the pigs just wouldn't do it,” she said. “And as soon as I walked in, it was like: ‘we'll do it now.’”

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“I think everybody who has animals that they have a strong bond with can understand that kind of thing,” Croney added. “To that degree, the pigs are no different from other other animals that we have strong social bonds with.”

Ultimately, the new study adds to the abundant evidence of sophisticated intelligence in pigs, which is scientifically interesting and also has ethical implications for their treatment, management, and care.  

“At the end of the day, I think the take-home message is this: We had no idea pigs were capable of doing even this level of conceptual learning,” Croney said. “If they can do this, what else could they be learning and responding to that I might not, as somebody interacting with them or working with them, be taking into consideration?”

“That forces me to be a little bit more careful, and a little bit more cognizant, of the impact I'm having on another sentient being,” she concluded. “I don't know that we do that enough for those of us who work with animals on a regular basis.”