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On the Intellectual Abilities of Chickens February 20, 2007

Posted by Johan in Off Topic, Sensation and Perception.

Retrospectacle has a post up on yet another in a long line of bizarre PETA ads. The general oddness of the ad aside, it makes the claim that

the cognitive abilities of a chicken rival that of cats, dogs, and even young humans

I’d be the first to admit that it’s difficult to argue over something which isn’t well defined – maybe by your definition, laying eggs and having feathers counts as showing high cognitive function, and frankly, in the absence of a commonly accepted definition of intelligence even in academia, I couldn’t really say much about it.

However, a good old paper by Hess suggests that perhaps, we should think twice before signing chickens up for public education. The picture you’re seeing above can’t really be from the original study, as it was carried out in 1956, so I imagine it’s from some replication. The chicken is wearing goggles which shift the its vision slightly to one side. The chicken’s ability to adjust to this change was measured rather cleverly by having the chicken peck for grain placed on clay, which ensured that each peck left a tidy mark to measure performance by.

This experiment, or a variant of it, is an old favorite in Psychology practicals. Basically, you make a human subject wear these goggles for some time, and test their performancy by having them point at a target with a ballistic movement. The interesting finding is that while performance is initially horrid, it improves quite rapidly as the subject practices. If you next remove the goggles and have the subject do yet another trial, performance is once again impaired, but in the opposite direction. So it would seem that we learn rather quickly to adjust our aim for the distortion that the goggles introduce.

Hess (1956) reported that this was not the case with chickens. Regardless of the number of trials, they never got any closer to the grain. As this was the 1950’s, long before Ethics committees, Hess was able to make this point very clearly, by reporting that two chickens had in fact died of starvation while wearing the goggles, despite having grains scattered around them.

So as long as we agree that the ability to learn is a crucial aspect of intelligence, the score appears to be humans 1 – chickens 0.


Hess, E.H. (1956). Space Perception in the Chick. Scientific American, 195, 71.



1. Humans Enjoy A Bird’s Eye View at Governomics - February 21, 2007

[…] these findings aren’t exactly fodder for a PETA argument against the unethical treatment of birds, they are useful for those of us interested in figuring out the psychophysics of behavior. This […]

2. corradoborg - June 16, 2007

Several research teams have recently published findings on chicken intelligence that have challenged old notions about avian cognitive abilities. For instance, scientists have found that chickens clearly understand cause-and-effect relationships, an advanced comprehension skill that puts their intellect beyond that of dogs. In the book The Development of Brain and Behaviour in the Chicken, Dr. Lesley Rogers, a professor of neuroscience and animal behavior, concludes, “[I]t is now clear that birds have cognitive capacities equivalent to those of mammals, even primates.”7

In one experiment that explored chickens’ understanding of causal relationships, researchers found that when injured chickens were offered the choice between regular food and food that contained a painkiller, the birds soon understood that the medicated food made them feel better, and they learned to seek it out it over the other choices. “The chickens will take the analgesic every time,” says Dr. Joy Mench, a professor in the Department of Animal Sciences at the University of California at Davis. They understood cause and effect and learned how to make the best decision.8

Chickens can also grasp other complex mental concepts. For instance, according to Evans, chickens are able to understand that objects still exist even after they are hidden or removed from view. This level of cognition is actually beyond the capacity of small human children.9 Researchers also recently reported that chickens “can anticipate the future and demonstrate self-control, something previously attributed only to humans and other primates.”10 Scientists made this discovery after they observed that when given the option between pecking a button and receiving a small food reward instantly or holding out for 22 seconds in order to receive a larger food reward, chickens in the study demonstrated self-control by holding out for the larger reward over 90 percent of the time.11

Chickens are social animals who form complex social hierarchies and interact in complex ways that are indicative of what anthropologists call “culture.” For example, researchers have shown that chickens learn from observing the success and failure of others in their community. One experiment that demonstrated this finding involved teaching one group of chickens to peck red and green buttons a certain number of times to obtain a food reward. Researchers were surprised to find that when a new group of chickens watched those who had learned how to push the buttons for food, the new chickens quickly caught on by watching the others. At a scientific conference, Dr. Christine Nicol, who worked on the on the study, told her colleagues, “They may be ‘bird brains,’ but we need to redefine what we mean by ‘bird brains.’ Chickens have shown us they can do things people didn’t think they could do. There are hidden depths to chickens, definitely.”12

Researchers have also found that chickens have a cultural knowledge that they pass down from generation to generation. John Webster, a professor at Bristol University in the U.K., set up a study in which he gave chickens a mixture of yellow and blue kernels of corn. The blue kernels were tainted with chemicals that made the birds feel sick, and they quickly learned to avoid the blue corn entirely (this is also another example of their understanding of cause and effect).

When the chickens in Webster’s study had their young, he spread yellow and blue corn around the farm, and even though he made it so that both types were harmless, the mother hens remembered that the blue corn had previously made them sick, and they steered their young away from it. In an article in the London Times, Webster explains, “What this tells us is that the mother hen has learnt (sic) what food is good and what is bad for her, that she cares so much for her chicks she will not let them eat the bad food, and she is passing on to her young what she has learnt (sic). To me, that is pretty close to culture—and an advanced one at that. Chickens are sentient creatures and have feelings of their own.”13

Scientists have been so impressed with the cognitive capabilities of birds that a group of international experts recently called for a new naming system to reflect the advanced nature of birds’ brains. According to an article that appeared in The Washington Post, “The new system, which draws upon many of the words used to describe the human brain and has broad support among scientists, acknowledges the now overwhelming evidence that avian and mammalian brains are remarkably similar—a fact that explains why many kinds of bird are not just twitchily resourceful but able to design and manufacture tools, solve mathematical problems and, in many cases, use language in ways that even chimpanzees and other primates cannot.”14

7 Lesley Rogers, The Development of Brain and Behaviour in the Chicken, CABI Publishing: Oxfordshire, U.K., 1995: 217.
8 Specter.
9 Grimes.
10 Jennifer Viegas, “Study: Chickens Think About Future,” Discovery News 14 Jul. 2005.
11 Viegas.
12 Ananova.
13 Valerie Elliott, “Why Did the Chicken Cross the Road?” London Times Online 18 Mar. 2005.
14 Weiss.

3. Johan - June 16, 2007

Corrado, I was going to thank you for taking the time to write such a thorough comment.

Then I punched a sentence into google and discovered that you just copied in the exact text from this page on GoVeg.com, a PETA website:


The bulk of the actual contents of the post can be addressed with a simple link:


Stay tuned for more animal behaviour posts in the next few days.

4. What exactly are you trying to tell me? « To strive, to seek, to find, … - January 22, 2013

[…] abilities of a chicken rival that of cats, dogs, and even young humans”, when there’s plenty of evidence to show […]

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