Excerpt from Gibson labels on the backside:

2 performers with camera viewfinders to their eyes are each other's subjects (observed) as they are simultaneously each other's objects (observers) in the filming of each other; the process is a relation of dependent, reciprocal feedback.

Dan Graham (1942-2022) was an American post-conceptual artist whose work consisted of performance art, installations, video, sculpture, and photography. Very much in the moment, Graham’s work was designed to incite and evoke a relationship between the viewer and an object that challenged in a thoughtful yet playful way a desire to reconsider time, space, and surfaces. Beginning in the late 1960s and into the late 1970s, Graham created largely performance-based pieces incorporating film and the new medium of video for his systematic investigations of cybernetics, phenomenology and embodiment. Emblematic of this early filmic work, “Two Correlated Rotations” (1969) was a perceptual, kinetic exercise that explored the interaction of two cameras, utilized as extensions of each performer's body, with the subjectivity of the viewer. 

Reproduced in Lucy Lippard, Six Years: The dematerialization of the art object.