“I think animals do experience regret, as defined as the recognition of a missed opportunity,” Dr. Brosnan said. “In the wild, these abilities may help them to recognize when they should forage in different areas or find a different cooperative partner who will share the spoils more equitably.”

Image Credit... Viktor Koen

No one knows, of course, exactly how this sense of regret affects an animal emotionally. When we see a dog slouching and bowing, we like to assume he’s suffering the way we do after a faux pas, but maybe he’s just sending a useful signal: I messed up.

“It’s possible that this kind of social signal in animals could have evolved without the conscious experience of regret,” said Sam Gosling, a psychologist at the University of Texas, Austin. “But it seems more plausible that there is some kind of conscious experience even if it’s not the same kind of thing that you or I feel.”

Marc Bekoff, a behavioral ecologist at the University of Colorado, says he’s convinced that animals feel emotional pain for their mistakes and missed opportunities. In “Wild Justice,” a new book he wrote with the philosopher Jessica Pierce, Dr. Bekoff reports on thousands of hours of observation of coyotes in the wild as well as free-running domesticated dogs.

When a coyote recoiled after being bitten too hard while playing, the offending coyote would promptly bow to acknowledge the mistake, Dr. Bekoff said. If a coyote was shunned for playing unfairly, he would slouch around with his ears slightly back, head cocked and tail down, tentatively approaching and then withdrawing from the other animals. Dr. Bekoff said the apologetic coyotes reminded him of the unpopular animals skulking at the perimeter of a dog park.

“These animals are not as emotionally sophisticated as humans, but they have to know what’s right and wrong because it’s the only way their social groups can work,” he said. “Regret is essential, especially in the wild. Humans are very forgiving to their pets, but if a coyote in the wild gets a reputation as a cheater, he’s ignored or ostracized, and he ends up leaving the group.” Once the coyote is on his own, Dr. Bekoff discovered, the coyote’s risk of dying young rises fourfold.

If our pets realize what soft touches we are, perhaps their regret is mostly just performance art to sucker us. But I like to think that some of the ruefulness is real, and that researchers will one day compile a list of the Top 10 Pet Regrets. (You can make nominations at TierneyLab, at nytimes.com/tierneylab.) At the very least, I’d like to see researchers tackle a few of the great unanswered questions:

When you’re playing fetch with a dog, how much regret does he suffer when he gives you back the ball? As much as when he ends the game by hanging on to the ball?