The Wundt Illusion is an optical illusion created by German psychologist Wilhelm Wundt in the late 19th century. It consists of two vertical lines of identical length, but when placed side by side, the line on the right appears longer than the line on the left. This illusion demonstrates
From Wikipedia
The Wundt illusion is a geometrical-optical illusion, a class of visual phenomena in which the perceived properties of simple lines or shapes differ from their true geometric properties. It was first described by the German psychologist Wilhelm Wundt in 1898.