Monkeys experience regret over a game of rock-paper-scissors

It's sometimes said that you should live life without regrets, but doing that means ignoring lots of information about how you could do things better. Even monkeys see the value in regret...at least after they throw rock instead of scissors.

Regret tends to get a bad wrap, but as with most things, it's all about moderation. A little bit of regret is important because it allows us to recognize where we went wrong and, hopefully, avoid repeating those same bad choices again. Of course, too much regret can become harmful when it makes us obsess about the past. But in either case, researchers had long assumed that only humans felt regret. But that's just because they'd never challenged monkeys to a game of rock-paper-scissors.

Yale researchers Daeyeol Lee explains why regret is so important:

"Regret serves us well most of the time, by helping us recognize choices that lead to bad outcomes. But sometimes regret can be very damaging...Our brain is wired to run these hypothetical simulations all the time. If you try to learn only from the actual outcomes of your own experience, this represents only a tiny fraction of information you can get from your world."

Lee and his colleague Hiroshi Abe designed an experiment where rhesus monkeys would play the game, receiving a large reward for winning, a small reward for tying, and no reward at all for losing. They then recorded the monkeys' neuronal activity.

Two things quickly became evident. First, the monkeys were aware not just of when they went wrong, but also how. If a monkey lost a game - say, it picked paper when the winning move would have been rock - then it became much more likely to choose the previous winning object in the next game - in this case, that means playing rock. That's a decent indication that the monkeys can imagine alternative outcomes and act on that knowledge, but does that mean they feel regret?

That brings us to the second set of findings. The monkeys' neuronal activity in these situations revealed they were experiencing both rational and emotional forms of regret in their prefrontal cortices. They saw the memory centers of the brain were relaying information to the monkeys about the preferred outcome, while the emotion centers fired off in response to this regrettable outcome.

Intriguingly, Lee says that determining the neural processes underlying regret could help us better understand debilitating mental illness where people obsess over the past to the exclusion of all else. He also says this work could help in the treatment of certain forms of schizophrenia, particularly those in which patients hallucinate. He says this might be caused by people losing the ability to distinguish between actual and alternative outcomes.

Via Neuron. Image via National Geographic.