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I've found the following picture online. It is about the moral/paradigm behind consistent behavior.

Image shows text and cartoon illustrations. Transcribed below.

Click to enlarge.

The image text says

  • A group of scientists placed 5 monkeys in a cage and in the middle, a ladder with bananas on the top.
  • Every time a monkey went up the ladder, the scientists soaked the rest of the monkeys with cold water.
  • After a while, every time a monkey went up the ladder, the others beat up the one on the ladder.
  • After some time, no monkey dare[d] to go up the ladder regardless of the temptation.
  • Scientists then decided to substitute one of the monkeys. The 1st thing this new monkey did was to go up the ladder. Immediately the other monkeys beat him up.

    • After several beatings, the new member learned not to climb the ladder even though he never knew why.
  • A 2nd monkey was substituted and the same occurred. The 1st monkey participated on [sic] the beating for [sic] the 2nd monkey. A 3rd monkey was changed and the same was repeated (beating). The 4th was substituted and the beating was repeated and finally the 5th monkey was replaced.
  • What was left was a group of 5 monkeys that even though never received a cold shower, continued to beat up any monkey who attempted to climb the ladder.
  • If it was possible to ask the monkeys why they would beat up all those who attempted to go up the ladder ... I bet you the answer would be ... "I don't know — that's how things are done around here" Does it sound familiar?
  • Don't miss the opportunity to share this with others as they might be asking themselves why we continue to do what we are doing if there is a different way out there.

This seems like an experiment, but now I'm wondering... Was this experiment ever conducted? If not, was any similar experiment conducted that shows the same effect?

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3  
Please link to the source of this picture. –  Oddthinking Nov 2 '11 at 23:20
9  
It sounds interesting until the last two frames--especially the very last--which makes it just look like another attempt at viral brainwashing. –  Flimzy Nov 2 '11 at 23:37
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All this needs is a tag line of Nadia in Mulligatawny did not forward this to all of her friends and was crushed by a toilet falling from a passing plane the next week... But if you forward it to all of your friends now Google will not start charging you for your search results. –  Chad Nov 3 '11 at 14:14
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There were several positive negative reinforcement experiments performed but this sounds like an extrapolation of predicted results combined with humanized responses. This story makes it sound like negative reinforcement alone can trigger this powerful anti social group behavior. Its a myth –  Chad Nov 4 '11 at 18:31
10  
You need ten monkeys. . . –  Rory Alsop Mar 28 '13 at 13:27

2 Answers 2

up vote 169 down vote accepted

The earliest mention I could find of this experiment was in the popular business/self-help book, Competing for the future by Gary Hamel and C. K. Prahalad (1996). Here is the quote from the book:

4 monkeys in a room. In the center of the room is a tall pole with a bunch of bananas suspended from the top. One of the four monkeys scampers up the pole and grabs the bananas. Just as he does, he is hit with a torrent of cold water from an overhead shower. He runs like hell back down the pole without the bananas. Eventually, the other three try it with the same outcome. Finally, they just sit and don’t even try again. To hell with the damn bananas. But then, they remove one of the four monkeys and replace him with a new one. The new monkey enters the room, spots the bananas and decides to go for it. Just as he is about to scamper up the pole, the other three reach out and drag him back down. After a while, he gets the message. There is something wrong, bad or evil that happens if you go after those bananas. So, they kept replacing an existing monkey with a new one and each time, none of the new monkeys ever made it to the top. They each got the same message. Don’t climb that pole. None of them knew exactly why they shouldn’t climb the pole, they just knew not to. They all respected the well established precedent. EVEN AFTER THE SHOWER WAS REMOVED! (Source)

The authors did not provide a source for this claim. This story was later repeated in various other popular business/self-help books.

Every source online I could find erroneously attributed the experiment to one of the above authors. No one, anywhere, seems to have a reference to the actual experiment.


C. K. Prahalad is deceased, but Gary Hamel is still alive. I tried contacting him several times, but unfortunately both he and his secretary were very evasive. The best I could get was

Our apologies, but Professor Hamel does not have the original source information at hand in terms of your request.

Given that there seems to be no evidence anywhere of this experiment ever actually taking place, that all trails of references eventually lead to the claim in this book, and that this is the earliest available mention of the experiment, until further evidence becomes available the most reasonable conclusion is that C. K. Prahalad or Gary Hamel made up the experiment for their book.


Even if the above authors were not the creators of the myth, there is still reason to believe that, as @Chad puts it (comments above), this claim is an "extrapolation of predicted results combined with humanized responses."

Here is a quote from an "anthropology professor who's worked with hundreds of monkeys over the last 30 years." When asked what he thought of the experiment, he responded succinctly with:

If you have bananas on a pole, you'll lose your bananas.

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4  
That last quote is interesting, I'm still wondering what Gary Hamel has to say about that. –  Tom Wijsman Nov 4 '11 at 21:06
    
@Tom: see edit. I've given up trying to contact him. Perhaps if more people ask, we can get a better response. –  BlueRaja - Danny Pflughoeft Nov 28 '11 at 18:47
    
Thank you for leaving a comment, it's interesting that it could be made up. I might look into contacting him. –  Tom Wijsman Nov 28 '11 at 18:51
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Followup question: if 4 more people replied that it's not a real experiment, would the next person reply without even bothering to do the research? –  JeffSahol Aug 5 '13 at 17:58
    
What do monkeys have to do with this? I thought this was about chimps? –  sbi Aug 23 '13 at 22:27

TL;DR: It sounds like a similar monkey experiment did take place, and the results were similar to that presented in the picture, but if this is the same experiment, most of the details are wrong.

The first google result for monkeys ladder experiment contains to the following information:

Stephenson (1967) trained adult male and female rhesus monkeys to avoid manipulating an object and then placed individual naïve animals in a cage with a trained individual of the same age and sex and the object in question. In one case, a trained male actually pulled his naïve partner away from the previously punished manipulandum during their period of interaction, whereas the other two trained males exhibited what were described as "threat facial expressions while in a fear posture" when a naïve animal approached the manipulandum. When placed alone in the cage with the novel object, naïve males that had been paired with trained males showed greatly reduced manipulation of the training object in comparison with controls. Unfortunately, training and testing were not carried out using a discrimination procedure so the nature of the transmitted information cannot be determined, but the data are of considerable interest.

Sources: Stephenson, G. R. (1967). Cultural acquisition of a specific learned response among rhesus monkeys. In: Starek, D., Schneider, R., and Kuhn, H. J. (eds.), Progress in Primatology, Stuttgart: Fischer, pp. 279-288.

Mentioned in: Galef, B. G., Jr. (1976). Social Transmission of Acquired Behavior: A Discussion of Tradition and Social Learning in Vertebrates. In: Rosenblatt, J.S., Hinde, R.A., Shaw, E. and Beer, C. (eds.), Advances in the study of behavior, Vol. 6, New York: Academic Press, pp. 87-88.

The above quote is found on page 88 of the 1976 document quoted above.

It is possible the claim is referring to this experiment, with diverging details, or that another experiment took place that was closer to the details in the claim.

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Do you have any evidence that this anecdote is based on that experiment, other than someone wrote it on the answers.com wiki? It doesn't seem like "the details are wrong" to me, it simply sounds like this was a completely different experiment. –  BlueRaja - Danny Pflughoeft Nov 4 '11 at 17:12
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@BlueRaja-DannyPflughoeft, after reading the paper link bellow, it does look like the beginning of the described experiment; learning passed on. It does fail to join all subjects that haven't interacted with the object and have them pass their knowledge to their fellow kin. I would say the folloing 'anecdote' uses the basis for this experiment and greatly builds upon it. The answer to the OP would be NO, it hasn't. scribd.com/doc/73492989/… –  Frankie Apr 15 '13 at 18:30

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