The four works assembled in Michael Snow’s “Closed Circuit” are not among the artist’s best-known. Visitors expecting the long mechanical arm of De La (1969–72) or the recto-verso double projection of Two Sides to Every Story (1974) will be disappointed. For all the bombast associated with the Guggenheim Bilbao, this is a small, quiet show. Yet its unassuming stature belies a conceptual clarity, as judicious selection creates a sharply honed portrait of an artist long devoted to exploring vision—embodied vision, machine vision, and the nexus between them. It is a portrait in which film, the medium for which Snow is best known, takes a backseat to questions of interactivity, real time, and surveillance. Snow’s concern with perception is signaled immediately by the titles of Sight (1968) and Observer (1974). Positioned at the entrance to “Closed Circuit,” Sight is a black window covering made of aluminum and plastic, mostly blocking the view of the Nervión river outside, save for a diagonal rhomboid aperture excised from its geometrical patterning. Faced with the resulting tension between interior and exterior, surface and depth—themes that recur elsewhere in the exhibition—binocular vision falters, leading to a phenomenological reduction whereby I see myself seeing. A similar self-consciousness emerges from …