How We
Fool Ourselves
More than a hundred years ago, in Berlin, a horse called Hans became famous. His owner, a retired teacher, would ask him questions such as “What is 3 plus 2?”, and Hans would tap his hoof five times. He got most answers right, even when strangers asked the questions. People called him “Clever Hans”, and his owner wasn’t cheating. So how did Hans do it?
💡 The Idea
In 1907 a psychologist called Oskar Pfungst found the answer. Hans got the right answer only when two things were true: the person asking knew the answer, and Hans could see them.
As Hans tapped, the person watching him waited, a little tense. When he reached the right number, they relaxed very slightly, without knowing it. Hans had learned to stop tapping at that moment. He was clever, but not at sums: he was clever at reading people. When the questioner was hidden, or didn’t know the answer, Hans was only guessing.
Nobody was lying. The people around Hans were fooling themselves. This is the trickiest kind of fooling, because the person being fooled is completely honest.
Three ways we fool ourselves
- Our bodies follow our hopes. Tiny movements we don’t notice can push a pendulum or signal a horse.
- We remember the hits and forget the misses. We remember the one dream that “came true”, and forget the hundreds that didn’t.
- Expecting to feel better can make us feel better. Even a sugar pill can make some people feel better for a while if they believe it is medicine. This is called the placebo effect, and it’s why people may honestly say that a useless remedy “worked”.
The answer: blind tests
In a blind test, the person being tested doesn’t know the right answer, so their hopes can’t steer the result. Doctors testing a new medicine go one step further. In a double-blind test, neither the patients nor the doctors giving out the pills know who is getting the real medicine and who is getting a dummy one, until the end.
The physicist Richard Feynman put it like this:
“The first principle is that you must not fool yourself, and you are the easiest person to fool.”
The easiest person to fool is yourself.
A blind test protects you.
🔗 Where You’ve Seen It
- Activity 2: The Pendulum That Knows the Answer
Your own hand moved the ring without your noticing. In the coin test, when you didn’t know where the coin was, the pendulum could only guess. - Activity 4: The 1995 Milk Miracle
Crowds came expecting a miracle, and they saw one. Few looked closely at where the milk was really going.
🌍 Use It Everywhere
A “lucky” shirt worn for cricket matches, a dream that “came true”, a remedy that “worked for my aunt”: these are all places where we can fool ourselves. Before you believe, ask: Am I remembering only the hits? Did I want this to be true? Would a blind test give the same answer?
The hits-and-misses diary. For one week, every morning, write down two guesses: “Will it rain today?” and “Will the first person I meet be wearing blue?” Each evening, mark each guess right or wrong.
At the end of the week, count your hits and your misses. Were there more misses than you expected? Without the diary, which ones would you have remembered?
For parents and teachers
- Clever Hans: Hans belonged to Wilhelm von Osten in Berlin. A commission in 1904 found no deliberate trickery; Oskar Pfungst’s experiments in 1907 showed that Hans was responding to tiny involuntary cues from his questioners. See “Clever Hans” (Encyclopaedia Britannica).
- A gentle point about medicine: the placebo effect is real, but it does not cure serious illness. Children should never stop or change a prescribed medicine without a doctor.
- Feynman’s quote is from his 1974 Caltech commencement address, “Cargo Cult Science”. See “Cargo Cult Science” (The Marginalian).
- Going further: ask children why the friend in the pendulum coin test must turn away too. (So that the friend can’t give unconscious clues, just as Hans’s questioners did.)
A Young Skeptics thinking tool, written with the assistance of AI tools, and reviewed by our editors. — CHARVAKA DESK