What to see and do: The top object appears to be smaller then the bottom one but they are actually the same size. Move the top shape over the bottom to see that they are the same size.
What's happening: They are the same size but the short edge of the red one is compared to the longside of the blue one. Therefore, the blue figures looks as if it were longer.
Credit: This illusion was discovered by the American psychologist Joseph Jastrow in 1889.
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