Rats Experience Regret Similar To Humans
June 9, 2014

Do Rats Have Emotions? New Study Shows They Can Experience Regret

Alan McStravick for redOrbit.com - Your Universe Online

In the 2007 Disney feature length Cartoon, Ratatouille, the lead character Remy was separated from his family due to his desire to save Augesten Gusteau's restaurant after reading the famed book "You Can Cook" during the exodus from the besieged farmhouse. That fateful decision and its immediate aftermath were portrayed in such a way that we, as human viewers, were meant to sense Remy's regret. But surely, rats are incapable of such an emotion, right? Don't be so certain.

“Regret is the recognition that you made a mistake, that if you had done something else, you would have been better off,” said A. David Redish, PhD, professor of neuroscience at the University of Minnesota Medical School's Department of Neuroscience. This definition, widely identified by both economists and psychologists, was the basis for new research that was able to definitively show that rats are capable of the cognitive behavior that, until now, was thought to be uniquely and fundamentally human: regret.

“The difficult part of this study,” says Redish, who worked with graduate student Adam Steiner, “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.”

To achieve this, Redish and Steiner created a sort of queue system in which rats were “asked” to determine how long they would wait in line for certain foods. “It's like waiting in line at a restaurant,” explained 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.”

Sticking with that theme, the duo named their research task “Restaurant Row”. Each rat subject is presented with a series of food options. But here is the kicker. Each “restaurant” had a set, limited amount of time available.

The idea that the subject rats possessed their own individual preferences was established clearly when many would wait longer for certain flavors over others. It was the measurement of these individual preferences that allowed Steiner and Redish to accurately measure what they termed as “good deals” and “bad deals.” Sometimes, the rat subjects would skip a good deal only to find themselves face to face with a bad deal.

"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.

The Restaurant Row study has practical future application for neuroscientists to eventually better understand why it is that humans do things the way that we do. Redish believes, with his study as a basis, future research will likely help us to understand how regret plays in the human decision making process.

The findings of this study were recently published in the journal Nature Neuroscience.