KOBE, July 16 — The poker face isn’t just for human card players. A 2024 study from Kobe University and the University of Tokyo has found that horses, when frightened, maintain a remarkably stoic outward appearance even as their hearts race. The researchers call it a ‘poker face’ response — and it appears to be a survival strategy hardwired by evolution.
The study used video stimuli to test the animals’ reactions. Despite elevated heart rates indicating genuine fear, the horses displayed no overt behavioral signs of distress.
They did not snort, paw at the ground, or attempt to flee. The researchers described this disconnect between internal physiological arousal and external calm as a sophisticated form of emotional regulation. How it works comes down to the pressures of being prey.
In the wild, a horse that visibly shows fear — by snorting or bolting — may draw the attention of a predator. A stoic response, by contrast, can be a survival strategy.
The study’s authors noted that this suppression of visible fear signals is consistent with evolutionary pressures on prey animals, which often hide signs of fear to avoid attracting predators. The study provides the first direct evidence of this phenomenon in horses using video stimuli. While similar muted fear responses have been observed in other prey species, such as deer and rabbits, in controlled settings, this is the first time researchers have demonstrated it specifically in horses with this method.
The finding suggests a level of emotional complexity that is easy to overlook. The horses were clearly frightened on the inside — their heart rates told that story — but they displayed no overt behavioral signs of fear. The researchers described this as a ‘poker face’ response, a term that captures the deliberate concealment of emotional state.
The study aligns with a growing body of research on prey species and their emotional lives. Deer and rabbits, for example, have shown similar muted fear responses in controlled settings.
The horse study adds a new data point, and one that is particularly striking because of the animals’ size and domestication. Even horses that live closely with humans, the study suggests, retain this ancient survival instinct. The researchers from Kobe University and the University of Tokyo are careful not to overstate their findings, but the implication is clear: what you see on the outside is not always what is happening on the inside.
For horse owners, trainers, and veterinarians, this could have practical implications. A horse that looks calm may still be experiencing significant stress.
The next question for researchers is whether this poker face extends to other emotional states, and how long the physiological arousal lasts after the threat has passed. For now, the study stands as a reminder that even familiar animals can surprise us with the subtlety of their inner lives.
