But a new study suggests rats feel regret similar to the way humans do. Scientists at the University of Minnesota Department of Neuroscience realized such after monitoring rats' brains following a bad decision or mistake.
The researchers did so by offering the specimens an initial food reward as well as the option to move onto to an alternate food reward.
The scientists defined regret as "the recognition that you made a mistake, that if you had done something else, you would have been better off." When the rats declined the first food offering, and it turned out the second was even punier, the rats were dejected and regularly turned back to look at the choice they had passed up.
Mostly importantly, scientists were able to show that the same part of the human and rat brain -- called the orbitofrontal cortex -- lights up during regretful situations.
"The hard part was that we had to separate disappointment, which is just when things aren't as good as you hoped," explained Professor David Redish, lead author of the new study. "The key was letting the rats choose."
The study was published this week in the journal Nature Neuroscience.