While regret has previously been viewed as an exclusively human attribute, new research suggests that monkeys too can experience the feeling.
A study conducted by researchers from Yale University found that the animals can visualise alternative, hypothetical outcomes to different situations.
The results, published in the journal Neuron, could help with the development of new ways to treat diseases including schizophrenia and depression, the researchers believe.
Researchers tested the monkey's brain activity while playing modified games of paper, scissors, stone and found that the monkeys were more likely to pick the winning symbol from the previous game if they lost that round. The monkeys received large rewards for winning, small rewards for a tie and nothing if they lost.
They way the monkeys adapted their match highlights the animals' ability to imagine a different outcome, the researchers believe.