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Chimps outsmart humans at simple strategy game

When it comes to simple strategy games, chimpanzees consistently outperform humans at tasks that involve short-term memory and predicting opponents' moves.

Screenshot by Michelle Starr/CNET

Having more complex cognitive reasoning skills doesn't necessarily make you better at simple tasks, a new study has found. When it comes to outwitting the competition, the chimpanzee seems to be smarter than a human.

Researchers at the California Institute of Technology have found that chimpanzees at the Kyoto University Primate Research Institute are consistently better at humans when playing simple competitive games.

In one game, called the Inspection Game, chimps and humans played a variation on hide-and-seek. In pairs of their own species (humans and chimps did not directly compete with each other for the study), the players sit back-to-back, each with a computer screen in front of them. After pushing a circle on the screen, they have to choose one of two boxes, right or left. They are then shown their opponent's selection.

Each player has a different role. The "mismatchers" have to choose the opposite of their opponent's selection, while the "matchers" have to choose the same as their opponent's selection. Each game lasted 200 rounds, and players that "won" a round were given a reward. In order to consistently win, players had to be able to anticipate their opponent's choices.

In game theory, there is a concept known as the Nash equilibrium. This means the balance that can be achieved when each player knows their opponent's strategies, but has nothing to gain by changing their own strategy. The 16 Japanese students participating in the study performed as expected: slow to learn their opponents' strategies, and not reaching the Nash equilibrium.

The six chimpanzees, however, learned the game and their opponents' moves rapidly, very nearly reaching the Nash equilibrium, even when the researchers swapped the chimps' roles and introduced higher rewards for specific choices. As the game changed, the chimps changed their strategies accordingly.

The experiment was also conducted with 12 adult men in Bossou, Guinea, facing each other and placing a bottle cap either right-way up or upside down, with a substantially higher reward -- a full day's earnings for the winner. They performed about on a par with the Japanese students.

There are several mitigating factors that could explain why the chimps were so good at the game. They were more familiar with the task, since it is similar to other tasks they perform at the facility; and they played in mother-child pairs, which means they may have instinctively known how the other would respond. However, the researchers discounted both of these explanations, since the Japanese students were also familiar with simple games, and the men in Bossou were known to each other.

Instead, the researchers hypothesise, the chimps' short-term memory -- previously demonstrated to be excellent -- could be the reason they are so good at memorising each others' strategies. As for why they perform so much better, chimps are more competitive, while humans are more cooperative, and chimps communicate more nonverbally, while human communication is largely verbal.

"Fights with other chimps and dominance hierarchies are central to their lives," said Rahul Bhui, Caltech graduate student and study co-author. "We have language and widespread cooperation which (chimps) don't need to worry about, and maybe that impairs our performance in these simple competitions. Maybe these were costs we paid for other abilities."

The full study, "Chimpanzee choice rates in competitive games match equilibrium game theory predictions", can be found online in the journal Scientific Reports.