Riley began investigating colour in 1967, the year in which she produced her first stripe painting. Following a major retrospective in the early 1970s, Riley began travelling extensively. After a trip to Egypt in the early 1980s, where she was inspired by colourful hieroglyphic decoration, Riley began to explore colour and contrast. In some works, lines of colour are used to create a shimmering effect, while in others the canvas is filled with tessellating patterns. Typical of these later colourful works is "Shadow Play".