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All experiments in psychology are not of this [cargo cult] type, however. For example there have been many experiments running rats through all kinds of mazes, and so on - with little clear result. But in 1937 a man named Young did a very interesting one. He had a long corridor with doors all along one side where the rats came in, and doors along the other side where the food was. He wanted to see if he could train rats to go to the third door down from wherever he started them off. No. The rats went immediately to the door where the food had been the time before. The question was, how did the rats know, because the corridor was so beautifully built and so uniform, that this was the same door as before? Obviously there was something about the door that was different from the other doors. So he painted the doors very carefully, arranging the textures on the faces of the doors exactly the same. Still the rats could tell. Then he thought maybe they were smelling the food, so he used chemicals to change the smell after each run. Still the rats could tell. Then he realized the rats might be able to tell by seeing the lights and the arrangement in the laboratory like any commonsense person. So he covered the corridor, and still the rats could tell He finally found that they could tell by the way the floor sounded when they ran over it. And he could only fix that by putting his corridor in sand. So he covered one after another of all possible clues and finally was able to fool the rats so that they had to learn to go to the third door. If he relaxed any of his conditions, the rats could tell. Now, from a scientific standpoint, that is an A-number-one experiment. That is the experiment that makes rat-running experiments sensible, because it uncovers the clues that the rat is really using - not what you think it's using. And that is the experiment that tells exactly what conditions you have to use in order to be careful and control everything in an experiment with rat-running. I looked into the subsequent history of this research. The next experiment, and the one after that, never referred to Mr. Young. They never used any of his criteria of putting the corridor on sand, or of being very careful. They just went right on running rats in the same old way, and paid no attention to the great discoveries of Mr. Young, and his papers are not referred to, because he didn't discover anything about rats. In fact, he discovered all the things you have to do to discover something about rats. But not paying attention to experiments like that is a characteristic of cargo cult science.

Richard Feynman#13

ObservationScientific methodBehaviorControlExperimentExperimentationPsychology

About this quote

What does it mean?
Rats learned to identify a specific door by subtle cues like texture, not by following a logical rule like third door down. This shows how subjects find unintended shortcuts in experiments, leading to unreliable results if not controlled.
In plain terms
Animals often use hidden clues instead of the intended task, so experiments must rule out these tricks.
What can you take from it?
Design experiments to eliminate unintended cues that subjects might exploit.

Where it applies

  • scientific research
  • testing hypotheses
  • behavioral studies

Putting it to work

  • audit experimental setups for hidden cues
  • randomize conditions to prevent pattern recognition

Questions to consider

  • How might hidden variables affect my current project?
  • What assumptions am I making about how others perceive my tests?

Another view

Not all scientific errors come from subject behavior; equipment or researcher bias can also cause issues.

More from Richard Feynman

  1. There is one feature I notice that is generally missing in 'cargo cult science'... It's a kind of scientific integrity, a principle of scientific thought that …

    Permalink to quote #12
  2. If I could explain it to the average person, I wouldn't have been worth the Nobel Prize.

    Permalink to quote #14
  3. You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... So let's…

    Permalink to quote #11

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