Rats Regret What They Didn't Do: Behavioral Neuroscience

Research shows rats can recognize the what-might-have-been

Posted Jun 09, 2014

I'm always on the lookout for what most people would consider improbable results or surprises in the field of cognitive ethology (the study of animal minds). However, if one considers Charles Darwin's ideas about evolutionary continuity -- "If we have or do something, 'they' (other animals) do too" -- then we shouldn't be all that surprised to discover fascinating aspects of the cognitive and emotional lives of nonhuman animals (animals). 

"Rats certainly show they can recognize the what-might-have-been"

Just this weekend I learned about a fascinating study that showed that rodents, in this case laboratory rats, show regret. The study was conducted by Adam Steiner and his mentor David Redish at the University of Minnesota. Their study, published in the prestigious journal Nature Neuroscience is called "Behavioral and neurophysiological correlates of regret in rat decision-making on a neuroeconomic task." The abstract reads as follows: "Disappointment entails the recognition that one did not get the value expected. In contrast, regret entails recognition that an alternative (counterfactual) action would have produced a more valued outcome. In humans, the orbitofrontal cortex is active during expressions of regret, and humans with damage to the orbitofrontal cortex do not express regret. In rats and nonhuman primates, both the orbitofrontal cortex and the ventral striatum have been implicated in reward computations. We recorded neural ensembles from orbitofrontal cortex and ventral striatum in rats encountering wait or skip choices for delayed delivery of different flavors using an economic framework. Economically, encountering a high-cost choice after skipping a low-cost choice should induce regret. In these situations, rats looked backwards toward the lost option, cells within orbitofrontal cortex and ventral striatum represented the missed action, rats were more likely to wait for the long delay, and rats rushed through eating the food after that delay."

Because the article is not available online for general readers, I found the following summary by Mary Bates titled "Rats Regret Making the Wrong Decision" to be a very good one to share. Science is not necessary linear and while these researchers "were looking at decision-making in rats ... something about the behavior of their subjects struck them as interesting. When a rat made a mistake, it stopped and looked backwards." According to Professor Redish, “Regret is the recognition that you made a mistake and if you had done something differently, things would have gone better.” 

It was the rats looking backwards that was the trigger to conduct a series of food preference experiments called "restaurant row" that showed that rats regretted what they didn't do. Steiner and Redish compared what rats did in regret conditions ("skipping a good deal only to find themselves with a worse deal") to what the rats did in disappointment conditions ("they made the right choice — taking a good deal or skipping a bad deal — but the next restaurant was a bad deal anyway"). They discovered that "the rats showed three behaviors consistent with regret. First, the rats only looked backwards in the regret conditions, and not in the disappointment conditions. Second, they were more likely to take a bad deal if they had just passed up a good deal. And third, instead of taking their time eating and then grooming themselves afterwards, the rats in the regret conditions wolfed down the food and immediately took off to the next restaurant."

While we don't know what the rats were feeling, "their behavior and neural activity patterns reflect the subtleties of regret seen in humans ... and [they] certainly show they can recognize the what-might-have-been."

We must use what we know to protect research animals

I hesitated to write about this project because it involved invasive research. However, a number of people encouraged me to do so because it's high time that we use what we know on behalf of animals who are used by the millions in invasive research and these results must be used to provide further protection to these clearly thinking sentient beings. Unfortunately, those responsible for amending animal welfare legislation for protecting research animals have been incredibly lame and delinquent in incorporating new discoveries into regulations. For example, we've known for years that mice display empathy and we also know that rats do too (please see "Empathic Rats Free Known Trapped Rats From Being Restrained" and references therein). Yet, these findings, published in prestigious professional journals as was this study, have not been used on behalf of these rodents. This is inexcusable.


Steiner, A. P. and Redish, D. (2014). Behavioral and neurophysiological correlates of regret in rat decision-making on a neuroeconomic task. Nature Neuroscience, June 8, 2014. doi: 10.1038/nn.3740.

Marc Bekoff's latest books are Jasper's story: Saving moon bears (with Jill Robinson; see also), Ignoring nature no more: The case for compassionate conservation (see also)and Why dogs hump and bees get depressed (see also). Rewilding our hearts: Building pathways of compassion and coexistence will be published fall 2014. (marcbekoff.com; @MarcBekoff



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