Bridget Riley, Untitled, study for 'Arrest' series

In this working drawing we gain an insight into Riley’s method of construction. The pencil lines which extend beyond the limits of the coloured gouache (indicating the boundaries of the finished painting) expose the movement of the curved bands sharply downward from left to right, and then gradually back upward. At the same time, the tonality moves gradually from light to dark, then quickly back again. The artist has referred to these opposing movements as the work’s ‘two centres’, and we can see a diagram of the two in action at the lower right, illustrating their interaction (‘slow – fast – slow’). She notes that ‘The viewer need not know any of this in order to enjoy the final painting, but I need to follow my thinking so that I can modify or change what I’m doing as I’m working.’ [Correspondance with the artist. Artist dossier, Department of Prints and Drawings, British Museum, London.]