Half the people in a famous experiment did not notice that the stranger they were talking to had been swapped for someone else.
In 1998, a researcher asked passers-by for directions. Halfway through, two men carrying a door walked between them, and a different researcher took over the conversation. About half of the people carried on as if nothing had happened.
Why is this true?
This is change blindness: the brain does not store a detailed picture of a scene, only a rough summary. When the change happens during an interruption, there is nothing to compare against.
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More about psychology
Psychology facts describe the shortcuts your mind takes without asking permission. We misjudge randomness, remember interrupted tasks better than finished ones, and change our answers when a group disagrees with us. The entries here stick to findings that have held up under replication, avoid the pop-science versions that overstate them, and explain what the effect really predicts about everyday behaviour.