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The implications of the Moses Illusion

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There's a simple question that gets answered wrong so frequently that it's acquired the name The Moses Illusion. It sounds like a minor trick, but it has the ability, under the right circumstances, to set you on a mental path toward major mistakes.

Answer this question quick — How many animals of each kind did Moses bring on the ark?


The answer is none. Noah was the one who built the ark. Moses was the one who led the Jews out of Egypt and wandered in the desert for 40 years. Some people got it wrong because they just sped through the question and thought, "Two." Some people got it wrong because they thought, "Wasn't it something like 14 of the clean beasts and seven of the unclean and please don't ask me about the difference between clean and unclean beasts." And some people got that it was a trick question. Congratulations. Take a minute to be smug about it.

The fact is, though, a lot of people would have gotten it wrong eventually, because there are whole tests full of these kind of trick questions. They ask who said, "Four score and 20 years ago," and give an answer as Abraham Lincoln, when actually Lincoln said, "Four score and seven years ago." They ask what country Margaret Thatcher was president of, instead of giving her correct title of prime minister. They semantic people out of a lot of right answers, and they do it by making the incorrect answers vaguely plausible, and often similar-sounding.


So what? What does it really prove, other than that psychologists are kind of jerks? On its own, it doesn't prove much, but if the tests go one step further, they can be very interesting. You see, when you hear a phrase, you may not remember it verbatim, but it will sound familiar if it's repeated. It has created a familiar pathway in your mind, and like someome with highway hypnosis, you will be likely to follow it later. After a long stream of twisted questions, researchers found that people were much more likely to get the "facts" that they were being tested on wrong, even when they were the ones framing them. Because they'd heard it in a slightly misleading phrase, they actually thought it was Snow White who lost her slipper instead of Cinderella, or that Macbeth said, "To be or not to be."

To get things wrong, you don't have to be told the wrong answer. You just have to be asked the wrong question.

[Via NCBI, Carnegie Mellon University]