Your mood is showing! Similarities between human and animal minds lend insights to animal feelings.
When you’re feeling bad, bad things feel worse.
It doesn’t feel good to have something you like taken away. And it feels even worse when you’re already in a bad mood.
Imagine you’ve just finished a long, frustrating day at work and you head to the freezer to grab that last ice cream bar you were saving. You find that it’s not there. Whoever took it better watch out, right? Now imagine you returned home from a productive, rewarding day at work and find the ice cream gone. Sure you’d be disappointed, but the person who ate your ice cream isn’t in mortal danger.
If someone was watching you, they would probably know whether your day put you in a good mood or a bad mood just by seeing your response to the missing ice cream. How we act when we lose an anticipated reward reveals something about how we are feeling. This is true of other animals as well. Since animal welfare is essentially about how animals feel, this predictable relationship between feelings and actions is useful for people interested in animal welfare.
Close up of a furry grey and brown rat peeking out from under wooden steps, sunflower shells nearby. Photo by Svetozar Cenisev on Unsplash.
How animals respond to reduced rewards reveals their mood, too.
Can we learn about animal welfare, or how animals feel, by measuring how they react to reward loss? It seems so. Several controlled studies have shown that once rats have learned that a big piece of food is waiting for them, they are quick to approach it and eat it up. Their speed of approach slows down if the piece of food is smaller, which makes sense. It’s less exciting and attractive. But rats who have been housed in barren or stressful conditions slow down even more than rats who have been housed in complex, enriching ones. The rats’ housing conditions induce a positive or negative mood, and that mood revealed in how the rats respond to the diminished reward.
Pig on muddy ground looking at camera, low sun, other pigs in background. Photo by Pascal Debrunner on Unsplash.
The same effect has been shown in pigs. Pigs on commercial farms are typically housed in pretty barren conditions that lack opportunities to explore or exercise, and when housed in this way they show more of a sensitivity to reward loss than pigs housed in more complex and enriching ways. It’s not surprising that pigs’ moods are negatively impacted by barren housing, but it is interesting that this approach can measure it.
How does this science help us help animals thrive in our care?
These results are exciting because they provide a potential way to “ask” animals how they feel about different conditions that aren’t so obvious. Another example of a promising way to ask animals how they are feeling is the judgment bias test (read about how dogs reveal their moods on the judgment bias test here and here). This is what animal welfare researchers want more of — ways to ask animals how they feel. Researchers are still determining how well the sensitivity to reward loss measure works outside of controlled, laboratory conditions, but perhaps in the future this approach can be used to ask animals how they feel about aspects of our care in zoos, animal shelters, and in our own homes.
Learn more about the researchers
Oliver H. P. Burman, Animal Behaviour, Cognition and Welfare Research Group, University of Lincoln, United Kingdom
Michael Mendl, Bristol Veterinary School, University of Bristol, United Kingdom
Lu Luo, Department of Animal Sciences, Wageningen University & Research, The Netherlands
J.E. Liesbeth Bolhuis, Department of Animal Sciences, Wageningen University & Research, The Netherlands
S. Ellis, Animal Behaviour, Cognition and Welfare Research Group, University of Lincoln, United Kingdom
Articles
Burman, O. H., Parker, R. M., Paul, E. S., & Mendl, M. (2008). Sensitivity to reward loss as an indicator of animal emotion and welfare. Biology Letters, 4(4), 330-333. Link to article.
Luo, L., Reimert, I., Graat, E. A. M., Smeets, S., Kemp, B., & Bolhuis, J. E. (2020). Effects of early life and current housing on sensitivity to reward loss in a successive negative contrast test in pigs. Animal Cognition, 23(1), 121-130. Link to article.
Ellis, S. L., Riemer, S., Thompson, H., & Burman, O. H. (2020). Assessing the external validity of successive negative contrast–implications for animal welfare. Journal of Applied Animal Welfare Science, 23(1), 54-61. Link to article.
