Chimpanzees make monkeys of humans in computer game


When it comes to simple competitive games, chimps make a monkey out of humans and make a genius out of John Forbes Nash Jr.

Chimpanzees playing each other in a simple matching game outperformed human players, apparently by paying closer attention to opponents’ patterns and adjusting more optimally, according to a study published Wednesday in Scientific Reports.

As a result, the chimps more often reached an equilibrium point described by Nash, where neither could do much better by adjusting strategy (think of all those frustrating stalemates in tic-tac-toe, for example).


Researchers believe the different outcomes could be the byproduct of a cognitive trade-off in the course of evolution. Humans left the trees and developed language, semantic thought and cooperation, while our distant cousins kept right on doing what made them so successful in the first place – competing, deceiving and manipulating.

Lost? Let’s just follow the chimps, then.

It’s called the Inspection Game, and it’s kind of an abstraction of a two-person game of hide-and-seek. Each player faces a computer screen the other can’t see, and chooses between two blue squares, left or right. One player is rewarded for matching the other player (right-right or left-left), the other for mismatches.

Laboratory chimps in Kyoto, Japan, outperformed 16 Japanese university students, and did the same against 12 men playing the game with bottle caps in Bossou, Guinea. Humans in Africa were just as far off from the equilibrium point as in Asia, the study found.

Even when researchers switched matchers and mismatchers and tinkered with the rewards (matches on one side of the screen or bottle cap earned more), the results were consistent: Chimps play more like Nash predicted.

It’s not that Nash (played by Russell Crowe in the 2001 feature film “A Beautiful Mind”) was wrong about humans and right about chimps. It’s just that in certain strategic games the older species is quicker and perhaps more “economical” in its calculations.

“It seems like they’re keeping better track of their opponents’ previous choices,” said Colin Camerer, a Caltech behavioral economist whose work on the neuroscience behind economic decision-making won him a MacArthur grant last year. “You can see, compared to the human subjects, they’re just more responsive. They’re keeping better ‘minds’ on what their opponents are doing.”


The Nash equilibrium is one of those concepts that is more readily recognized and described mathematically. In this type of game, said Camerer, “it’s the point at which no one is leaving a pattern that leaves themselves vulnerable to exploitation. So there’s no more competitive improvement that they can get.”

Exactly how our primate cousins build on their memory of behavioral patterns and whether they conceptualize their counterparts’ minds has been hotly debated and won’t be resolved by the study. But its results are consistent with previous work that shows a chimp advantage in several other competitively strategic tasks, according to the Caltech-Kyoto University research team.

Tetsuro Matsuzawa, a primatologist at Kyoto University and a study coauthor, has shown previously that chimps are faster and more accurate than humans at tasks involving working memory. He suggests such expertise might have been reinforced by natural selection during chimpanzee evolution, while time diluted the skill among humans as they acquired more abstract cognition involved in language - a feature that also made humans more cooperative.

Or as Camerer put it, “One theory is that the humans are overthinking it, and the chimps have a simpler model.”