It also identified with new scientific understandings of how the brain controls vision and the essential role of the viewer in experiencing a painting. (dwigmore.com)
Dan Graham, (born March 31, 1942, Urbana, Illinois, U.S.), American artist whose work addressed such notions as the dual role of the viewer (or audience) as both perceiver and perceived. (britannica.com)
Working contemporaneously to such continental Op artists as Victor Vasarely and Julio Le Parc, Riley was included in the landmark exhibition «The Responsive Eye» at MoMA in 1965, which emphasised the active role of the viewer and the potential slipperiness of seemingly objective geometric forms. (davidzwirner.com)