Animals with spines in the UK could soon be legally recognized as “sentient” beings with feelings if a bill being debated in Parliament moves forward. Should the bill become law, it could get lawmakers to consider animals’ feelings, like pain or even joy, when crafting any new policy. The bill is part of a larger push by the government to set high standards for animal welfare in the country.

That raises a lot of questions for humans. Are animals used for food or fur bored in their pens, for instance? And what do you do with an individual who might react differently to a situation than its peers, based on its unique personality? 

If passed, the bill would create an “Animal Sentience Committee” in charge of evaluating how well the government considers those feelings in its policies. For now, the bill focuses on vertebrates; animals with spines. But there’s a push from animal rights advocates to expand its proposed protections to invertebrates, like octopuses and lobsters, that have recently surprised scientists with what they’re capable of doing and potentially feeling.

To better understand what it means for an animal to “feel,” The Verge spoke with Kristina Horback, director of the Animal Behavior and Cognition Lab at the University of California, Davis. 

This interview has been lightly edited for length and clarity.

I know this can get a little complex but, first of all, how do you define sentience?

In teaching undergraduates at UC Davis, I use a definition of: capable of sensing environmental cues — sensation, perception, and then responding to those cues. In that definition, you include invertebrates, insects, so many things. But there’s definitely confusion with taking a philosophical slant in adding feeling — not only feeling but consciousness, awareness of that feeling. That’s where it gets really muddled, trying to “prove” consciousness: the actual acknowledgment of “I’m experiencing pleasure right now” or “I’m experiencing pain” and so on.

Right now, there’s a lot of focus on pain, which is understandable. We’re seeing some evidence of learned behavior, where the animal will avoid certain areas in their environment where they experienced pain. For example, some fish species will avoid an area where they were once hooked in their mouth. So we have enough evidence of the experience of pain, and learned behavior from that experience of pain — but it’s going to be really difficult to have sufficient evidence right now that the animal is on a conscious level of, “Wow, that hurt.”

This is where I think a lot of this legislation comes into play, is “shouldn’t we kind of err on the side of caution?” In particular, there’s this interest in vertebrate mammals and birds that have the same brain structures, they’re showing the same behavioral responses that we see in humans in terms of body postures, or learned changed behavior for experiences of pain and anxiety and stress. Shouldn’t we assume that they are also experiencing that on a conscious level? But that gets heavy in philosophy as well.

How has our understanding of animal sentience changed over time?

Well, I think you can go back as far as philosophers like Rene Descartes, who viewed them as automatic machines where information goes in from the environment and then they just have sort of reflex responses and that’s it. 

But we’ve had a really great merging of other psychologists, cognitive scientists, and primatologists. Think of your classic Jane Goodall, people who actually sit and take time to view the animals and say, “Now hold on, there’s a lot more going on than just in and out in terms of response to the environment or response to finding a mate, survival, and that’s it.”

I think it’s just taken time for humans to become more clever to design experiments where we can acknowledge the capacities of other animals. We are so limited because we are primates ourselves, that all we think about is vision and spatial cues. But that doesn’t work for dolphins, you know. We’ve got to think like the species.

It was really neat to see it spark so many different fields in terms of, what about personality? Or what about boredom? Do animals experience boredom? Because we’ve already kind of had an acceptance that animals experience pain. But these other levels of complex experiences like boredom or guilt — a lot of scientists are getting together to see, can we find evidence of that? We’re no longer viewing animals as just robotic objects that take in information and spit out information and just survive and die. There’s a lot more going on in between.

So we can say now that animals have personalities?

Yes, there’s certainly so much literature out there — going from insects and reptiles and birds to your great apes and marine mammals — looking at personality. It could be an animal of the same sex, and the same family group, and the same rearing environment, but one is always more aggressive than the other or one is always more cautious than the other. You know, there’s a style in terms of how they respond to their world. That’s personality.

In terms of comparative psychology and animal welfare science, you know, we all are aiming at understanding capacities and experiences of individual animals. I think it’s a wonderful progression. I think it’s pretty easy for a lot of humans to acknowledge differences among their pets, and this is just kind of expanding it out now in terms of livestock or lab animals even. We want all lab animals to be the exact same, but the thing is, they’re not. That’s what I think is moving forward. It’s not just, “the lab rat does this.” It’s, “Well, it depends on…” you know, and then finishing the sentence because they’re individuals. 

What impact might this bill have if it passes?

It’s easy to see how it relates to farm animal treatment, like new housing requirements or enrichment requirements, or the treatment of animals in transportation. And then it could kind of expand to the import and export of livestock. If you put a bunch of sheep or cattle on a ship and send them somewhere, is that going to be changed now? That’s kind of the level I see it directly impacting commerce and trade for these products. And then it could get even larger. If we’re still just sticking to vertebrates, that can expand to fur animals or so many other uses of animals in medical fields. If it goes forward, a lot of things need to move as well to make it work.