Bridget Riley's "Current" presents a sea of movement and contrast. She wanted to create a piece which involved the space between the painting and the viewer, and she achieves this through optical illusion. The wavy lines seem to move up and down, undulating like an ocean current and acting very much like elusive waves that one can not seem to quite locate. Curved forms seem to come out towards the viewer and makes him or her sometimes dizzy or nauseous. At times the intense movement even creates a sense of color and tires out the eyes. All of this accoplishes Riley's goal of making "the space between the picture plane and the spectator...active", but it does it in a strong and almost violent way. The viewers felt shock and sometimes anger.
This is an example of Op art, in which artists used knowledge about visual perception, science, and technology to create their art.