Sign of regret: Rats know when they've lost a good thing

University of Minnesota researchers have determined that rats can express regret, an emotion scientists have long thought is unique to humans.

In a report published this month in the journal Nature Neuroscience, Professor David Redish of the university's Department of Neuroscience and graduate student Adam Steiner, detailed how they put lab rats in a situation where they could obtain food at any of four stations.

The rats encountered varying delays at each station and had to decide whether to wait out the delay, or head to the next station.

Sometimes they passed up a good deal, like a favorite food with a short wait time, for a station with a bad deal, like a long wait and a not-so favorite food.

Redish said brain scans showed activity in the same area of the brain that humans show in moments of regret, which a human might express by saying "if only I had done that."

"What we find in this 'skip a good deal, take a bad deal' situation [is] the rats will pull up short," he said. "They look backwards."

Redish said the research could help further understand human regret and decision making.