'Imposible triangle', c 1954.
© Science Museum / Science & Society Picture Library
This is the first model of the 'imposible triangle' one of a series of 'imposible figures' designed and constructed by English geneticist Lionel Penrose 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.