Push and pull

An optical sensation colors cause: the impression that each hue appears to recede or advance to a different depth from the eye. This term was coined and the concept promoted by painter Hans Hofmann (born in Bavaria, active in the USA, 1880-1966), often associated with Abstract Expressionism. His late paintings are characterised by the juxtaposition of strongly colored rectangles, which he said displayed this push and pull effect. The paintings were often worked out by pinning rectangles of colored paper to the canvas.