Why Scientists Believe Some Animals Feel Regret

Defining Regret in Scientific Terms

To understand animal regret, scientists first needed to establish a clear definition that could be objectively observed and measured. In humans, regret is defined as a negative emotion experienced when realizing that a different choice would have led to a better outcome. Crucially, it involves counterfactual thinking—the ability to compare what happened with what could have happened. When studying animals, researchers look for behavioral indicators suggesting that an animal recognizes it made a suboptimal choice, shows a negative emotional response to this realization, and subsequently modifies its behavior. This operational definition allows scientists to design experiments that can test for regret-like experiences while avoiding anthropomorphism—the attribution of human characteristics to non-human entities without sufficient evidence.

The Groundbreaking Rat Studies

The first compelling evidence for animal regret came from Dr. A. David Redish and his team at the University of Minnesota in 2014. They designed an ingenious experiment called "Restaurant Row," where rats had to decide whether to wait for preferred foods or move on to potentially less desirable options. When rats skipped waiting for a favored treat only to encounter a longer wait at the next station, they exhibited distinctive behaviors: they paused, looked back at the previous food station, and showed neural activity in the orbitofrontal cortex—a brain region associated with regret in humans. Most tellingly, after these experiences, rats adjusted their subsequent decision-making to avoid repeating the same mistake. This pattern strongly suggested a regret-like experience rather than simple disappointment, as the rats appeared to be comparing their actual outcome with what could have been had they made a different choice.

Neurological Evidence in Mammalian Brains

The neurobiological basis for regret-like experiences in animals provides some of the most compelling evidence for this phenomenon. When humans experience regret, specific brain regions activate, particularly the orbitofrontal cortex, anterior cingulate cortex, and hippocampus. Remarkably, when rats and primates make suboptimal decisions in experimental settings, researchers observe activity patterns in homologous brain regions. Using advanced techniques like functional magnetic resonance imaging (fMRI) and single-cell recordings, scientists have documented that these neural signatures in animals closely resemble those seen in humans experiencing regret. The orbitofrontal cortex, in particular, shows remarkably similar patterns of activity across mammalian species during decision-making tasks where subjects appear to recognize missed opportunities. This neurological evidence suggests that the basic neural machinery for regret-like experiences evolved long before humans appeared, serving important functions in decision-making and behavioral adaptation.

Primate Studies: Our Closest Relatives

Research with our evolutionary cousins—chimpanzees, bonobos, and other primates—has yielded particularly strong evidence for regret-like experiences. In a landmark study at the Max Planck Institute, researchers presented chimpanzees with a game where they could choose between immediate small rewards or delay gratification for larger ones. When chimps impulsively selected smaller rewards and then witnessed the larger rewards they missed, they displayed distinctive behaviors: head-clutching, self-directed grooming, and vocalization patterns associated with distress. Follow-up studies demonstrated that these primates subsequently adjusted their strategies, showing improved self-control after experiencing these apparent regret episodes. What makes these findings especially significant is that chimpanzees appeared to mentally replay their previous choices, suggesting the counterfactual thinking that defines true regret. Additionally, capuchin monkeys in similar experiments have been observed refusing to participate in subsequent trials after making suboptimal choices, suggesting an emotional response to their decision-making errors.

Beyond Mammals: Evidence in Birds

The capacity for regret-like experiences may extend beyond mammals to avian species, particularly corvids (crows, ravens, and jays) and certain parrots. These birds demonstrate remarkable cognitive abilities, including tool use, problem-solving, and potentially metacognition—awareness of their own knowledge states. In a fascinating study with western scrub jays, researchers found that these birds would adjust their food-caching strategies after experiencing theft, suggesting they anticipated regret over potential future losses. African grey parrots tested in delay-of-gratification tasks showed behavioral patterns resembling disappointment and possibly regret when they failed to wait for preferred rewards. When they impulsively selected lesser rewards, some parrots engaged in self-directed behaviors like feather-pulling and vocalized in patterns associated with frustration. While the neural mechanisms remain less well-understood than in mammals, these behavioral patterns suggest that regret-like experiences might have evolved independently in birds with complex cognitive abilities, highlighting how certain emotional capacities may arise whenever they provide evolutionary advantages in decision-making.

The Role of Counterfactual Thinking

At the heart of genuine regret lies counterfactual thinking—the ability to compare what actually happened with what could have happened had a different choice been made. This cognitive capacity was long thought exclusive to humans, but accumulating evidence suggests otherwise. When rats in the Restaurant Row experiment looked back at the food station they had abandoned, researchers interpreted this as a possible sign of counterfactual thinking. Similarly, when chimpanzees display frustration after choosing smaller immediate rewards over larger delayed ones, they appear to be comparing their actual outcome with the alternative. These observations suggest that some animals possess at least a rudimentary ability to entertain "what if" scenarios. To test this more directly, researchers have developed innovative experiments where animals must choose between options with clearly visible alternatives and consequences. The behavioral and neurological responses observed during these moments of "choice consideration" strongly suggest that certain animals can mentally simulate alternative outcomes—a fundamental prerequisite for experiencing true regret rather than simple disappointment.

Distinguishing Regret from Disappointment

A critical challenge in animal cognition research is distinguishing genuine regret from simpler emotions like disappointment. While disappointment occurs when outcomes fail to meet expectations, regret specifically involves self-blame for making the wrong choice among alternatives. To address this distinction, researchers have designed clever experimental protocols. In one approach, animals face scenarios where they either actively choose between options or have outcomes randomly assigned to them. The key finding is that animals like rats and primates show different behavioral and neural responses when poor outcomes result from their own choices versus when the same outcomes occur by chance. For example, rats in decision experiments exhibit specific neural signatures in the orbitofrontal cortex only when they "made a mistake," not when they simply received less-than-optimal outcomes through no fault of their own. Similarly, primates show more intense self-directed behaviors like scratching and grooming following poor choices they made themselves. These differential responses to choice-based versus random outcomes provide compelling evidence that some animals experience something closer to human regret than mere disappointment.

Evolutionary Advantages of Regret

Why would regret evolve in non-human animals? From an evolutionary perspective, regret serves important adaptive functions by improving future decision-making. When an animal experiences a negative emotion after making a suboptimal choice, this emotional tag helps reinforce learning and memory of the mistake. Studies show that animals exhibiting regret-like responses tend to make better decisions in subsequent trials, suggesting that these emotional experiences enhance learning efficiency. Additionally, regret may serve social functions in highly cooperative species. For instance, primates that make decisions affecting group outcomes sometimes display appeasement behaviors suggesting they recognize when their choices negatively impact others. This social dimension of regret could enhance group cohesion and cooperation. The fact that regret-like experiences appear most developed in species facing complex ecological challenges requiring flexible decision-making supports the theory that regret evolved as a sophisticated form of emotional learning—one that helps animals navigate environments where choices have complex, delayed consequences and where learning from mistakes quickly confers significant survival advantages.

Methodological Challenges in Studying Animal Emotions

Researching emotions like regret in animals presents significant methodological hurdles. Without verbal reports, scientists must rely on behavioral observations, physiological measurements, and neurological data—each with limitations. Behavioral indicators might have alternative explanations, while neural activity patterns, though suggestive, don't definitively prove subjective experiences. To address these challenges, researchers employ convergent methodologies, seeking evidence from multiple approaches before drawing conclusions. They also apply careful controls to rule out simpler explanations for observed behaviors. Another significant challenge is avoiding anthropomorphism—the inappropriate attribution of human characteristics to animals. Scientists combat this by establishing operational definitions based on observable phenomena rather than subjective interpretations. Despite these difficulties, the field has made remarkable progress through increasingly sophisticated experimental designs, such as creating scenarios where animals must make decisions with clearly visible alternatives and consequences, allowing researchers to observe reactions to missed opportunities in real-time. These methodological innovations continue to strengthen the case for regret-like experiences in certain animals while maintaining scientific rigor.

Implications for Animal Welfare

The growing evidence that some animals experience regret has profound implications for animal welfare practices. If animals can mentally compare what happened with what could have happened, they may suffer psychologically from poor environments or limited choices. This perspective is prompting reconsideration of care standards for captive animals in zoos, laboratories, and agricultural settings. For example, traditional housing systems that offer minimal choice might inflict a form of psychological harm previously unconsidered. Progressive zoos are now implementing choice-based enrichment programs where animals can select between different activities, environments, and even when to participate in training sessions. In laboratory settings, researchers are developing protocols that offer research animals more agency, potentially reducing stress and improving both welfare and data quality. Perhaps most significantly, this research challenges utilitarian views of animal suffering that focus solely on physical pain, suggesting that psychological states related to choice, agency, and regret should be factored into ethical calculations about how we treat other species.

Philosophical Implications and Consciousness

The discovery of regret-like experiences in animals has sparked profound philosophical discussions about animal consciousness and moral standing. Regret requires several sophisticated cognitive capacities: self-awareness, mental time travel, and counterfactual thinking. If some animals possess these abilities, even in rudimentary forms, it suggests their inner lives may be richer and more complex than previously acknowledged. This evidence challenges traditional philosophical boundaries between humans and other animals, particularly regarding consciousness. Philosophers like Peter Singer have argued that the capacity for suffering, rather than intelligence or language, should determine moral consideration. If animals experience complex emotions like regret, their capacity for suffering may extend beyond physical pain to include psychological distress related to choice and agency. These findings also contribute to ongoing debates about animal personhood and rights. While scientific evidence cannot alone resolve these philosophical questions, it provides crucial empirical grounding for ethical discussions about how we should treat different species based on their cognitive and emotional capacities.

Future Research Directions

The study of animal regret remains a young and evolving field with numerous exciting research directions. One promising avenue involves expanding investigations to a wider range of species, particularly those facing complex ecological challenges requiring sophisticated decision-making. Marine mammals like dolphins, with their large brains and complex social structures, represent particularly interesting candidates. Technological advances are also opening new possibilities, with miniaturized neural recording devices allowing researchers to monitor brain activity in freely moving animals making real-world decisions. Genetic research offers another frontier, potentially identifying shared genetic pathways underlying emotional processing across species. Additionally, computational modeling approaches are helping scientists formalize theories about how regret-like experiences might function in different neural architectures. Perhaps most intriguingly, some researchers are exploring potential applications of this knowledge, such as developing animal-computer interfaces that could give captive animals more meaningful choices and potentially reduce regret-like experiences. As this research progresses, it will likely continue to blur the once-sharp distinctions drawn between human and animal emotional capacities.

Conclusion: Rethinking the Emotional Lives of Animals

The emerging science of animal regret fundamentally challenges our understanding of the emotional lives of other species. What was once considered uniquely human appears to exist, at least in rudimentary forms, across various mammals and potentially some birds. This research doesn't merely add another emotion to the list of what animals might feel—it specifically identifies a complex, cognitively sophisticated experience that requires mental time travel, counterfactual thinking, and self-evaluation. The implications extend from philosophical reconsiderations of consciousness to practical applications in animal welfare, potentially transforming how we treat and relate to other species. As we continue to unravel the mysteries of animal cognition, we may find that the emotional gap between humans and other animals is narrower than we once believed, compelling us to extend greater moral consideration to the creatures with whom we share this planet and whose inner lives may be richer and more complex than we have previously imagined.