Photography by Leonard Whistler

Shepard Tables - Optical Illusion

Shepard Tables is an optical illusion first published in 1990 as "Turning the Tables" by Stanford psychologist Roger Shepard in his book Mind Sights, a collection of illusions that he had created. It is one of the most powerful optical illusions, typically creating length miscalculations of 20–25%.

This illusion is based on a drawing of two parallelograms, identical aside from a rotation of 90 degrees. However, when the parallelograms are presented as tabletops, we see them as objects in three-dimensional space. One table seems long and narrow, with its longer dimension receding into the distance. The other table looks almost square because we interpret its shorter dimension as foreshortening. According to Shepard, "any knowledge or understanding of the illusion we may gain at the intellectual level remains virtually powerless to diminish the magnitude of the illusion".

I made a YouTube video about the Shepard Tables: Shepard Tables - Optical Illusion.