Illusion of movement
Op Art, also known as optical art, is a type of art that features optical illusions. The way that lines, shapes, space and colour are used can fool our eyes and brain to see movement that is not really there.
Op Art works are abstract. They are based on geometric designs such as parallel lines, spirals, waves, circles and checkerboard patterns. Often these are produced in black and white or highly contrasting colours. The designs make it difficult for our eyes to rest on one area. The viewer's eyes constantly move over the images and this creates feelings that the work itself is moving.
Bridget Riley's Uneasy Centre features black and white circles painted with lines of varying width. The circles create a series of rings each with a slightly different centre.
This arrangement creates a sense of form and depth. But it is impossible to decide if there is a form rising out of the painting or sinking back into the canvas.
As our eyes try to make sense of the image, the form seems to keep changing. This creates a sense of movement.