The Poggendorff Illusion is an optical illusion first described by Johann Karl Friedrich Zöllner in 1860. It is an illusion of misalignment, in which two parallel lines appear to be misaligned when intersected by a third line. The illusion is named after Johann Christian P
The Poggendorff illusion is a geometrical-optical illusion that involves the misperception of the position of one segment of a transverse line that has been interrupted by the contour of an intervening structure. It is named after Johann Christian Poggendorff, the editor of the journal, who discovered it in the figures Johann Karl Friedrich Zöllner submitted when first reporting on what is now known as the Zöllner illusion, in 1860. Although Zöllner was focused on a different illusion, the misalignment of the diagonal lines revealed a distinct visual phenomenon. The Poggendorff illusion has become a widely studied example of spatial misperception in vision science and psychology. It has been used to investigate theories of perceptual systems, neurological function, and cognitive development.