Ten questions · about four minutes

Not everyone sees this

Some of what follows will look obvious to you and impossible to the person sitting next to you. These are not tricks. The differences are real, they hold up over time, and they say something about how your particular eyes and brain settled.

One rule. Answer what you actually see right now, not what you remember being the correct answer. Several of these figures are well known. Knowing the answer does not change what you see, and what you see is the whole point.

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Every image here is drawn by the page rather than photographed. Nothing depends on your screen showing a particular image correctly. Percentages come from people who have taken this, and they move as more people do. None of this diagnoses anything.