Spirals Optical Illusion

Stare at the center dots in these spirals. Are they the same size?

See Another Random Optical Illusion

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The spirals are the same size.

Explanation

The movement of an animation can fool you into thinking the inward spiral is smaller than the outward spiral. This seems to be because we fixate on a point to compare the size. With this optical illusion that point keeps getting moved inward or outward depending on which direction the optical illusion is spinning.