Chimps can be taught to play Rock Paper Scissors as well as four-year-olds

Thomas McMullan Read more August 11, 2017

In a breakthrough for both cognitive studies and human-primate schoolyard relations, scientists have successfully managed to teach a group of chimpanzees the rules of Rock Paper Scissors.

Chimps can be taught to play Rock Paper Scissors as well as four-year-olds

A team, led by researchers from Kyoto University in Japan, has demonstrated that chimps are capable of grasping the relationship between the three hand signals of the gestural game.

Seven chimps of various ages were chosen from the university’s Primate Research Institute, and presented with a computer-controlled series of tests. Instead of actually making the hand signals themselves, the chimps were given a pair of illustrated options on a screen, and had to choose the winning hand – paper beating rock, rock beating scissors and scissors beating paper.

The chimps undertook 48 trials a session, three sessions per day. The researchers first displayed only rock-paper pairs, and when the chimps reached a score of 90% correct responses, they changed this to only rock-scissors, then scissors-paper. Once they’d proven an understanding of the basic pairings, the chimps were given sessions where all three hands were mixed. In each session, if the correct option were chosen, the computer would chime and drop an apple slice. If the wrong option were chosen, a buzzer would sound and no food would be given. chimp_rock_paper_shotgun_computer_test

Five of the seven chimps managed to finish their training, after an average of 307 training sessions. As well as pictures of chimpanzee hands, the animals were also shown pictures of human hands, which they also managed to comprehend. Interestingly, of the three pairings it was the final option, scissors-paper, that the chimps had most difficulty understanding.

The researchers write in a paper about their research that this indicates “difficulties in completing the circularity” of the three gestures. The scientists also conducted the tests on children, albeit with fewer apple slices and more pictures of happy chimps by way of reward. Ranging in age between three and six years, the children grasped the rules quickly, at an average of five trials for all three pairs. Those under the age of four, however, were completely useless, largely relying on chance to score points.

Much like the chimp’s difficulty with the final scissors-paper pairing, the researchers point to the trouble for those under the age of four had with understanding the circular relationship between the three gestures. The scientists also note that they can’t rule out familiarly with the game amongst the older children.

“This suggests that children acquire the ability to learn a circular relationship and to solve a transverse patterning problem around the age of four years,” said lead researcher Jie Gao. “The chimpanzees’ performance during the mixed-pair sessions was similar to that of four-year-old children.”

It might not quite be Planet of the Apes, but the team’s research show how are capable of learning circular relationships between signs. Whether or not the chimps will use this newfound knowledge to decide who gets to sleep in their enclosure’s hammock remains to be seen.