FunNature & AnimalSuperstitious Pigeons and the Monkeys and Ladder Experiment

Superstitious Pigeons and the Monkeys and Ladder Experiment


Avoid crossing paths with a black cat, going under a ladder, throwing salt over your shoulder, consulting the horoscope daily, the spirits, the cosmic energies with which to cure ailments through reiki , the evil eye, palmistry, astrology, feng shuithe list of superstitions of which human beings are victims is as long as it is irrational .

In general, a superstition is a belief according to which some type of cause and effect relationship is established between phenomena that, in reality, do not present a causal relationship . The student who uses a pen to take an exam and gets a very good grade, and since then decides to use that same pen because it brings him luck; the person who always buys the lottery ticket in the same administration because an important prize is always distributed there; or who decides to cross himself before the plane takes off because, in this way, he feels protected by a superior power. These are all everyday examples of superstitious behavior.

In reality, the student’s pen will not change the result of the exam, but how well prepared the syllabus is. In reality, all the tenths have the same probability of hitting, and if that lottery administration always distributes important prizes, it is because it sells many more numbers. And in reality, the gestures that a passenger makes with his hand will not have a favorable influence on the flight, but the good weather, the correct operation of the plane, the good condition of the runway, the good coordination between devices and the skill of the pilot.

But the human being is not the only superstitious animal . Assuming causes and effects as true in unrelated events is something that many species do. And among all the experiments, one of the most striking is that of Skinner and his pigeons .

the superstitious pigeons

Operant conditioning is a way of stimulating desirable behaviors and avoiding or eliminating undesirable ones. Unlike Pavlovian classical conditioning , which associates a stimulus with a behavior, operant conditioning works by associating the behavior with its consequences.

But sometimes, perceived consequences are not always real consequences. And it is precisely what Burrhus F. Skinner discovered in 1947 in one of his experiments with pigeons.

The animals were prepared – they were left without eating for a certain time – and placed in experimental cages where no type of conditioning was carried out. Just a five-second timer provided a small amount of food for the animal . However, over time, the animals acquired a specific behavior that had not been induced by any external agent.

In his study, Skinner states that one of the pigeons circled the cage two or three times, always counterclockwise, before obtaining food. Another stuck her head obsessively and repeatedly into one of the upper corners of the cage until she saw the food fall. Another pecked towards the ground but without touching it, and raised its head again to check if the food had arrived yet. Different behaviors in different animals , none of them predominant, but all surprising .

The conditioning process happened because when the food arrived, the animal was performing some action, whatever it was . And like the student who clings to his pen, the pigeon clung to that behavior as if it were what he fed him. They assumed a cause and effect relationship between the behavior and receiving food, not knowing that the reward fell regardless of whether or not they performed their action.

And they kept repeating it even when it didn’t work, when they didn’t get anything. In some cases, the animal repeated the behavior up to ten thousand times before realizing that what had never really worked had stopped working. And it was enough that the food fell again once or twice for a new superstitious behavior to replace the previous one.

But although the one with the pigeons is the first rigorous example of animal superstition behavior, there is another experiment that is also very striking.

The (fake) experiment of the monkeys and the ladder

If there is a widely known example of an experiment in which the superstition of animals is analyzed, it is the famous experiment of the monkeys, the ladder, the bananas and the hose .

A quick Google search for the words “banana ladder monkeys” found almost half a million results. They explain an experiment that some scientists supposedly carried out with a few monkeys. The versions vary depending on who tells it, but all the stories have the same background.

A group of researchers put five monkeys in a cage with a ladder. On the ladder they placed some bananas. When one of the monkeys climbed the ladder to get the food, the rest of the monkeys received a jet of cold water.

The response of the monkeys was aggressive against the intrepid one who had dared to climb the ladder. Every time someone tried to reach the bananas, the others reacted violently to prevent them from reaching their goal, thus avoiding the cold water. After a while, no monkey tried to pick the bananas , despite the temptation.

Then, one of the monkeys is replaced by another that had never suffered the unpleasant consequences. But every time the rookie, unaware of the problem with the hose, tried to reach the bananas, the other animals jumped on him to stop him.

One by one all the monkeys were replaced, until in the resulting group there was no animal left that had received the cold water . However, they all perpetuated the violent behavior as the newest monkey in the cage tried to climb the ladder to reach the bananas.

Of course, as a good story, it has its moral: if we could ask those monkeys what is the reason for the violent attack against the one who wants to reach the food, none of them would know that it is a trap and that the others would receive a discharge of water, implemente would think it’s the right thing to do, because it’s always been that way .

Fortunately, the experiment never happened . Actually, the origin of the story is in a now defunct blog of marketing expert Michael Michalko. He said it was based on an experiment carried out by Gordon R. Stephenson on the cultural acquisition of a specific learned response among macaques. However, Stephenson’s published work does not correspond at all to the experimental conditions explained in Michalko’s story.

In fact, it is very unlikely that an experiment of this nature would even be considered; it is doubtful that any bioethics committee would allow such unnecessary suffering to be administered to animals. Although it is true that monkeys, like humans, can acquire superstitious behavior.

However, there is a reflection that can be obtained from this story, beyond the obvious.

When the moral becomes a paradox

The bogus experiment of the monkeys and the ladder is often used as an example. In addition to being so widespread on the internet, in some universities they teach it as a real experiment.

The worst thing about this false experiment and its disclosure is not the role of villain in which it leaves scientists, who subject poor primates to torture for no reason, and without answering any kind of scientific question.

Those who reproduce the story without verifying its sources or its veracity are, paradoxically, falling into the same error as the primates in the story, repeating a behavior out of inertia, without considering whether it is really true. Well, that story continues to be told, and always has been .

The human being is still a deeply superstitious animal. From time to time we should stop to think about those poor and metaphorical monkeys, and learn from their hypothetical and unreal sacrifice.



Nogueras Pérez, R. 2020. Why we believe in shit: how we deceive ourselves. Kailas.

Skinner, B. F. 1947. «Superstition» in the pigeon. Journal of Experimental Psychology, 38, 168-172.

Stephenson, G. R. 1966. Cultural acquisition of a specific learned response among rhesus monkeys. Primatologen, 19, 280-288.


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