"Woulda-coulda-shoulda" as Monkeys Ponder What Could Have Been - Report

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Monkeys Ponder What Could Have Been

It's a good thing monkeys can't gamble. New research shows these primates are capable of "woulda-coulda-shoulda" thoughts, like those that keep gamblers at the tables.

Monkeys' brains respond to rewards that they observe but do not experience - so-called fictive outcomes - and anterior cingulated cortex (ACC), a region of the brain thought to be involved in learning from experiences and adapting behavior. They monitored the monkeys' brain neurons while the animals played a game designed to study fictive thinking.

The monkeys were shown eight white cards arranged in a circle. Each card had a color underneath that corresponded to a specific reward, in this case, a certain amount of juice. One prize was larger than the others - a high value reward. Over many trials, the monkey learned to associate the color green with the biggest reward. After the monkey picked a card, all the cards were turned over, and the monkey was shown the prizes that it missed, and then given the reward.

The researchers found that the neural response was proportional to the reward given - the bigger the reward, the more the neurons fired. And the neurons responded the same way to fictive rewards. This result shows that "nerve cells in the ACC, which we already knew carry information about experienced rewards, also carry information about fictive rewards, information about the rewards that got away," said Platt.

Learning from mistakes

The monkeys also altered their behavior depending on the size of the fictive reward.

If the monkey missed out on a big reward in one trial, it was more likely to choose the card that had offered that large reward in the next trial. This is similar to what people do when they