Monkeys playing rock-paper-scissors regret bad choices

Ever had a regret? Seems like a human thing, this feeling that you could’ve done something better, differently. Well, it may not be just a human thing.

According to researchers at Yale University, publishing in the May 26, 2011 issue of Neuron, monkeys can facepalm with the best of us. Our primate cousins can, like us, feel remorse over the road not taken, at least when it comes to Rochambeau, more commonly known as “rock-paper-scissors.” For those who haven’t papered a rock lately, in this game, rock breaks scissors which can cut paper, which can cover (and defeat) rock. It’s a great way to make random decisions, especially if you have three children (or monkeys?), ages 4, 8, and 10.

The Yale study, though, involved rhesus monkeys. Daeyeol Lee and co-author Hiroshi Abe monitored the activity of nerve cells in the monkeys, which are commonly used in primate studies. The animals played a monkified, simulated version of rock-paper-scissors and got juice treats for winning and nothing for losing.

During the play, they showed the ability to imagine different outcomes for the game. How? If paper defeated rock in one game, in the next game, the monkeys tended to go for the symbol that defeats paper – the scissors. That means they’d reviewed their initial performance and decided on a sort of monkey version of a replay. They’d hypothesized a different outcome, evaluated the road not taken, and adjusted their actions accordingly. In this way, they are smarter than my four-year-old, who still predictably throws “rock” every time he plays this game because he likes rocks. The child still has some lessons to learn about regret … or at least about probability.

As the monkeys Rochambeau’d, the Yale investigators monitoring their neural activity saw the smart-part of the brain, the cortex, light up with activity. They even identified one area of the brain linked to choosing an action with a different outcome. Another brain area related to the emotional feeling of regret. Activity in the regretful neurons seemed to drive a monkey’s decision to go for a different choice in the next game, linking the two brain regions. This information, if it translates to the human brain, could be useful in helping people whose regrets become such fixed obsessions that their quality of life deteriorates.

In spite of this risk, regret has a purpose. Without it, we’d never learn from our mistakes but instead continue choosing rock over and over again just because we like rocks. Learning from loss or review of a road not taken, it seems, may be as important to monkeys as it is to us.

These regretful monkeys have once again taught us that humans haven’t cornered the neural or emotional market on much of anything. As Daeyeol Lee and Hiroshi Abe have shown, monkeys are just as capable of Monday-morning quarterbacking as any human.

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