Riley was born in London and studied art first at Goldsmiths College and later at the Royal College of Art, with fellow students including (Sir) Peter Blake and Frank Auerbach. She left college early to look after her sick father, and suffered a mental breakdown shortly thereafter. After recovery she took on a number of jobs, including several as an art teacher.Towards the end of the 1950s, Riley began to produce works in a style recognisably her own. This style came from a number of sources. A study of the pointillism of Georges Seurat, and subsequent landscapes produced in that style, led to an interest in optical effects. The paintings of Victor Vasarely, who had used designs of black and white lines since the 1930s, are an obvious influence. Particularly in later works, the influence of futurists, especially Giacomo Balla, can also be discerned.