Sometimes it’s the apparently simple questions that prove the trickiest. For instance, even people familiar with the Bible have a hard time correctly recalling how many animals of each kind Moses took with him on the ark. The answer: Zero, silly. Noah was the guy with the ark, not Moses.
It’s not just trick questions about Old Testament patriarchs that prompt this sort of cognitive slip-up. Studies have shown that a majority of people faced with similarly off-kilter queries about familiar subjects (“What did Goldilocks eat at the three little pigs’ house?”) tend to overlook anomalous key words if they sound like the correct word or are conceptually related to it. Psychologists call this pitfall the “Moses Illusion,” and our overwhelming susceptibility to it might seem to indicate that our species is not the sharpest knife in the evolutionary drawer. But in fact, some scientists see this quirk as evidence of our brains’ unusual sophistication.
Consider this: When researchers pose the Moses question in hard-to-read cursive writing, many fewer people fall prey to the illusion. That’s because our brains perform a kind of constant triage in approaching different tasks: Some are assigned to a quick-thinking system that boils down easy questions to their essentials for faster processing; others go to a slow-thinking system that ponders each element of a more arduous problem more carefully. As part of its triage process, the brain looks for cues that will help sort easy tasks from difficult ones. Sometimes the cues are deceptive: Practically everything about the Moses question signals that you can breeze right through it. Cursive writing, though, signals that you’re performing a difficult task and should slow down.
Similarly, when people are asked to furrow their brows while answering trivia questions, they proceed with more care. So to really meditate on the secret of the Moses Illusion, furrow your brow as you read this quote from the Nobel-winning psychologist Daniel Kahneman: “When faced with a difficult question, we often answer an easier one instead, usually without noticing the substitution.”