This dissertation explains how and why some American artists investigated visual phenomena and heightened perception during the 1960s and 1970s. As an analytical account grounded in the perceptual experience of artworks and in archival research of the claims artists made for their creations, this study is centered around the themes of re-sensitizing one’s body and perceptual faculties, the process of empirical discovery, and the ultimate inability of language to satisfactorily describe sensory phenomena. In Chapter 1, I establish a brief intellectual history of research concerning the sensory faculties from fields in the humanities, including psychology, philosophy, and art history. In Chapter 2, I analyze Judd’s art-critical concept of optical phenomena and consider the art about which he wrote, including his own, on the basis of this tentative classification. In Chapter 3, I evaluate John Chamberlain’s lacquer paintings in terms of the visual phenomena generated by his innovative paint mixtures and application techniques, then consider his provisional separation of intuition and intellect. In Chapter 4, I examine Robert Irwin’s efforts to refine his visual attentiveness and, in the course of doing so, I also test the accompanying artworks he made that demand such unusually acute observation. In Chapter 5, I argue that distinguishing physical, pictorial, and reflected visual phenomena in Larry Bell’s pieces proves to be an exceptional challenge, a problem compounded by the inefficacy of trying to communicate visual discoveries using language. In the Conclusion, I demonstrate that by restoring the role of heightened perception and sensory discovery to the history of art of the 1960s and 1970s, this dissertation helps to preserve the complexity and variety of works made during that time. / text