A new research has shown that rats exhibit behaviors consistent with regret, a feeling once thought to be unique to humans.

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To measure the cognitive measure of regret, scientists developed a task that asked rats how long they were willing to wait for certain foods. Basically, they made them decide if they want to wait more for food they like more; and they let them make mistakes.

“Regret is the recognition that you made a mistake, that if you had done something else, you would have been better off,” said Redish. “The difficult part of this study was separating regret from disappointment, which is when things aren’t as good as you would have hoped. The key to distinguishing between the two was letting the rats choose what to do.”

So they gave them a choice between “restaurants” – either to wait more and eat better food, or wait less and eat ‘meh’ food.

“It’s like waiting in line at a restaurant,” said Redish. “If the line is too long at the Chinese food restaurant, then you give up and go to the Indian food restaurant across the street.”

First of all, the study showed that rats do tend to wait more when they get food they like even more. They are able to overcome their initial instincts – something which was also once thought to be unique to humans. But researchers took things even further.

They measured the rats’ personal preferences, in order to understand what is a good deal or a bad deal for them. Sometimes, they would rush to the food and get a bad deal. After they did this, they started to exhibit behavior consistent with regret.

“In humans, a part of the brain called the orbitofrontal cortex is active during regret. We found in rats that recognized they had made a mistake, indicators in the orbitofrontal cortex represented the missed opportunity. Interestingly, the rat’s orbitofrontal cortex represented what the rat should have done, not the missed reward. This makes sense because you don’t regret the thing you didn’t get, you regret the thing you didn’t do,” said Redish.

Now, they hope to better study this feeling of regret, building on these animal studies and ultimately understanding how regret affects human decision making.

Journal Reference: Adam P Steiner, A David Redish. Behavioral and neurophysiological correlates of regret in rat decision-making on a neuroeconomic task. Nature Neuroscience, 2014; DOI: 10.1038/nn.3740