Now scientists have discovered that chimpanzees have hidden talents, too. In a new study published in the journal Primates, grad student Gao Jie (Kyoto University, Japan and Peking University, China), worked with a team of researchers to teach chimpanzees the rules of the Rock-Paper-Scissors (RPS) game. She already knew that chimps understand hierarchical relationships but she was curious to know if they could also learn to understand circular relationships.
This was a challenge because RPS relies on a circular relationship between the three different hand signals: rock beats scissors, scissors beats paper, and paper beats rock. Understanding circular relationships requires a higher level of cognitive skill and is useful for negotiating complex relationships, solving problems, and gaining new knowledge.
Working with an established group of chimps who already understood working on touchscreens, Gao taught them about each pairing separately, before showing them randomized pairings using images of human and chimpanzee hands.
“If they chose the correct answer, they would get a piece of apple for a reward, and a happy sound (chime),” she explained. “If they had a wrong choice, they would only get a buzzer.” This video shows just how quickly they could recognize the hand signals.
At first, Gao found that the chimps had difficulty recognizing the human hands: “Chimpanzees did not seem to understand that they were similar at first, so I was also interested in the body recognition of chimpanzees. Do they really know that chimpanzee hands and human hands are the same organ?”
Once they’d learned the first pairing, the chimps learned the second one quickly. But the last pairing proved more troublesome, because it completed the circle, and it took them a while to grasp this concept. On average, it took around 300 sessions for them to fully understand the relationships.
“We had five chimpanzees out of seven learned the RPS game,” Gao said, “So chimpanzees are able to understand the circular relationship.”
The researchers then moved on to preschoolers aged between three and six.
“We also did the same experiment in children,” Gao explained, “and we found children older than four years old could learn this game rule. Also, chimpanzees’ performances are equal to that of children at four years of age.”
It seems that at four years old, children began to play strategically rather than relying on luck to win the game. Gao now intends to teach the chimpanzees to play the actual Rock-Paper-Scissors game, and see whether they can learn to strategize too.
So next time you play a quick game of Rock-Paper-Scissors with your kids, remember that child’s play is not always as simple as it looks. Next time, let’s see how those chimps do on these car games for kids!