During the 1960s, English painter Bridget Riley became a pioneer of the Op art (optical art) movement. After studying at Goldsmiths College and the Royal College of Art in London, Riley began her artistic career as an illustrator at J.Walter Thompson advertising agency; whilst working for the agency, Riley developed her distinct style of monochrome geometric patterns which produce an optical illusion. Towards the end of the decade, Riley had begun to experiment with colour, and continued to do so whilst travelling during the 1970s and 1980s. As well as painting on canvas, Riley has created large-scale murals for a number of institutions, from the Tate to St Mary's Hospital. Today, the Op artist's work is on display in galleries and museums across the world from Glasgow to Boston. Riley's early pieces have continued to exceed their estimates at auction, with her 1967 work, Chant 2, selling for $5.1 million in 2008.