One morning last summer I fed Barley his dog food as I usually do, half in his bowl and half in a knobby, pineapple-shaped toy that he has to nose around the floor to release food little by little. Although this time I was in a hurry, and I provided him both the bowl and the silly-looking pineapple at the same time, placing the pineapple next to the bowl as I turned away to start making breakfast for my daughters.

A moment later, I heard the sound of the pineapple bumping around the kitchen floor and pieces of kibble scattering out. At first, I was surprised Barley had chosen to work for his food by tossing the pineapple around rather than just eating the same food out of the bowl. Then I smiled to myself as I realized Barley had just demonstrated a phenomenon shown by many animals, the preference to work for food when the same food is freely available. Scientists have named this contrafreeloading.

Contrafreeloading is interesting because it doesn’t make evolutionary sense.

It’s a curious phenomenon because theories of animal behavior predict that animals should minimize the energy they spend and maximize the energy they gain. Doing so should help them maintain strength and produce more offspring, so this behavior should be under strong selection pressure over generations. But when animals contrafreeload (choose not to freeload, choose to work for their food), they are spending extra energy.

Contrafreeloading first caught the attention of scientists in the 1960s when studies showed that laboratory rats preferred to press a lever to obtain food pellets rather than eat from a food dish. Since then, contrafreeloading has been reported in dozens of species, including chimpanzees, chickens, grizzly bears, wolves, giraffes, and pigs.

Cats may be uniquely rational freeloaders.

Yet, for some reason, the only species to consistently buck the trend is the domestic cat.  Cats’ preference for freely available food was first demonstrated in the 1970s, again in a laboratory. Recently Dr. Mikel Delgado questioned whether that finding, so out of line with the research on all other species, may have been due to the laboratory cats being more hungry, and their hunger level tipping them away from contrafreeloading. In some previous studies, researchers had found that contrafreeloading decreases when animals are very hungry.  

So Delgado and her colleagues from the University of California – Davis set up an experiment to test for contrafreeloading in 20 well-fed, healthy pet cats residing in people’s homes. The researchers gave the cat owners a puzzle feeder that required cats to scoop food out of tunnels and compartments using their paws, and one simple round plastic feeding dish. Cats were only included in the study if they knew how to get food from the puzzle.

Owners simply provided half the food in the puzzle and half the food in the dish (just like I did for Barley that morning), and left both available for 30 minutes a few times per day. A camera was set up on the toy & dish for the researchers to review, and owners weighed the amount of food that started and remained in both the puzzle and the feeding dish.

What did the researchers find? Cats were not contrafreeloaders. They were freeloaders. Not a single cat preferred to eat food from the food puzzle more than from the dish. All but two cats did eat from the puzzle from time to time, but overall, the dish was strongly preferred. When discussing the results, the authors said something that I thought would make cat owners smile:

“In general, cats appear to conserve energy to the greatest extent possible, minimizing the amount of time and effort required to meet their caloric requirements.”

So, why are the cats behaving differently than other animals? The authors suggest that cats may be different than other animals, perhaps having something to do with their specific predatory hunting style. But they also consider that most previous research has happened in more sterile, boring laboratory environments. Perhaps finding ways to work for food is something animals do more often when they feel understimulated or bored. Then it wouldn’t be such a curious behavior after all, if working for food served the purpose of mental stimulation, especially in cases where an excess of food is available to support survival and reproduction.

Does this information help us help animals?

Was Barley bored that morning that he surprised me by choosing the pineapple toy? I’ve repeated the offer to Barley several times over recent months. There are days he chooses the food bowl over the pineapple toy. If I were taking systematic data on Barley (are you surprised that I’m not?), I would guess that it would show he chooses the bowl more often. But, does his choice on a given day tell me anything about how he’s feeling at the time? Could this be a new way to ask animals how they are feeling?

To advance animal welfare, and find more ways to help animals thrive in our care, we need more ways to ask them how they are feeling. I’m taking this line of thinking a bit further than the current science, but perhaps the relationship between contrafreeloading and animal emotions is something to explore as we try to understand how animals feel, and how we can help them thrive in our care.

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The first author, Dr. Mikel Delgado, writes a pretty great blog about cat behavior and science, What Your Cat Wants.

The recent study of pet cats: Delgado, M. M., Han, B. S. G., & Bain, M. J. (2021). Domestic cats (Felis catus) prefer freely available food over food that requires effort. Animal Cognition, 1-8. Link to article.

An early study of contrafreeloading in laboratory mice: Jensen GD (1963) Preference for bar pressing over “freeloading” as a function of number of rewarded presses. Journal of Experimental Psychology, 65:451– 454. Link to article.