New research by a University of Minnesota neuroscience professor and a graduate students found that rats are capable of feeling regret – the first time it's been identified in a non-human mammal, the BBC reports.
And the concept of regret is something very specific, Redish tells the BBC – not just disappointment that things aren't working out.
“Regret is the recognition that you made a mistake and if you had done something differently, things would have gone better,” he says.
The experiment, which Wired details, involved having rats run past four different spokes, each leading to a different type of food (called "Restaurant Row," and pictured at right).
When the rat approached a spoke, a tone indicated how long the rat would have to wait to receive the food, Wired explains. It would have to choose whether to wait and take the food, or continue on to the next spoke – no going back.
The researchers tailored the experiment to each rat's flavor preference, putting a wait time threshold to each animal for each flavor, Wired says. For example, in the experiment, the researchers would make the rat wait a shorter time for a food it liked at one, but the rat would pass on it. Then at the next spoke, at a food it liked equally, the researchers would make the rat wait a much much longer time.
When the rat found out it had taken a worse deal, when it could have gone to the next spoke and gotten a much better deal, it responded with regretful behavior, Redish tells National Geographic.
They were more likely to take a bad deal after a regretful decision; they would eat the bad-deal food in a few seconds (a human-like behavior, Redish says), rather than a grooming session followed by a slower consumption of the food; or they would look back at the previous spoke they skipped – the spoke that had a shorter wait, National Geographic reports.
There were indicators in the rats' brains as well, and it reflected the same brain activity in humans, the BBC writes.
In humans, the orbitofrontal cortex is active when a person feels regret, Redish tells the BBC. When rats recognized they'd made a mistake, that same area of their brain became active.
"Interestingly, the rat's orbitofrontal cortex represented what the rat should have done, not the missed reward," Redish says. "This makes sense because you don't regret the thing you didn't get, you regret the thing you didn't do."
The BBC spoke with the University of Oxford's Dr Mark Walton, who reviewed the research. He tells the BBC the findings are "significant," calling it a "clever way" to look at rats' cognitive process – and potentially opening up a window to see how they act in the wild.
Matt Roesch, a neuroscientist at the University of Maryland, tells National Geographic he's "intrigued," calling the ability to see the feeling within the rat's brain "exciting."
He'd like to see a subsequent experience focus on how addiction may change the regretful behavior, National Geographic says.
The findings were published in the June 8 edition of Nature Neuroscience.