Rats feel regret, experiment finds

With only an hour to eat, a diner hurries into his favorite restaurant. Deterred by a modest wait, he leaves, only to be burned by an even longer wait at the next restaurant. He immediately regrets his decision. This may seem like a typical “woulda, coulda, shoulda” situation — except in this case, the diner is a rat.

In laboratory tests, rodents exhibit regret, scientists report June 8 in Nature Neuroscience. After forgoing a good meal for a bad one, rats pause, glance back at what could have been and change their subsequent behavior. Scientists even caught signs of regret in rats’ brains: Nerve cells behaved as though the rats were back at the scene of the missed opportunity.