'Imposible staircase', 1950s.
© Science Museum / Science & Society Picture Library
This is the first model of the 'imposible staircase' one of a series of 'imposible figures' designed by English geneticist Lionel Penrose FRS (1898-1972) in the 1950s. Penrose's discovery of the 'imposible figure' laid the foundation for the scientific study of illusions and investigations into the psychology of human perception. The Dutch artist M C Escher (1898-1972) was heavily influenced by Penrose's discovery, and incorporated an 'imposible triangle' into his well known 'Waterfall' lithograph.