Geometric illusions
Straight lines that bend, equal lengths that look unequal and shapes that appear out of nowhere.
Geometric illusionsCafé Wall IllusionPerfectly parallel rows of tiles that seem to tilt into wedges.
InteractiveGeometric illusionsMüller-Lyer IllusionThree identical lines that look clearly different in length.
Geometric illusionsEbbinghaus IllusionA circle among giants looks small; among dwarfs it looks big.
Geometric illusionsPonzo IllusionTwo equal bars on converging rails look like different lengths.
Geometric illusionsZöllner IllusionShort hatches make long parallel lines seem to tilt toward each other.
Geometric illusionsFraser SpiralConcentric circles of twisted cord that look like one big spiral.
Geometric illusionsHering IllusionTwo straight red lines bulge apart over a burst of rays.
Geometric illusionsPoggendorff IllusionA straight diagonal looks misaligned where a bar crosses it.
Geometric illusionsJastrow IllusionTwo identical arcs, but the lower one always looks bigger.
Geometric illusionsKanizsa TriangleA bright white triangle appears from nothing but three cut-out discs.Advertisement
How shapes get distorted
Geometric illusions reveal the shortcuts your visual system uses to judge length, angle, straightness and size. Lines are compared with their neighbours, acute angles are exaggerated, converging lines are read as depth, and missing edges are filled in when the simplest explanation needs them. Each illusion here has a reveal button so you can check the truth for yourself.