Who hasn’t felt a pang over the path not taken, the door not picked, or the bet not placed?

Humans apparently aren’t alone in feeling regret. Other primates appear to experience it, too, according to a study published today in Science.

Duke University researchers enlisted monkeys in a simian version of the television game show Let's Make a Deal to test whether they also wondered about what might have been.

Juice was subbed for cars and vacations. There were, however, no monkey fill-ins for Monty Hall and Carol Merrill.

The thought process of regret is complex and involves the anterior cingulate cortex (ACC) in conjuring not only a past outcome but also imagining alternative presents and changes to future behavior.

As the monkeys guessed where they might find a larger reward, researchers found that the choices were based on calculations of previous experience, leading the monkeys to a sweet reward more often than random guessing would have.

The monkeys' ACC neuron activity also increased both when they received their prize and when they were shown the prizes they missed, hinting at an imagination of missed opportunities.

"This is the first evidence that monkeys, like people, have 'would-have, could-have, should-have' thoughts," Ben Hayden, a neurobiologist at Duke University and lead study author, said in a statement.

Image courtesy of stoa767 via Flickr