Reciprocity of Light is an artwork exploring photographic representation, architecture, and bodily interactivity.  Working with commingled lights and sensors, in 2007 I developed a rudimentary means to display a viewer’s shadow cast from a point light source onto an array of light sensitive cells such that the shadow is produced in a display of light, a reversal of our normal phenomenological expectation of a shadow as a denial of light.  As the project developed, it became clear that this means of image production could encompass an entire room, resulting in an installation that was originally exhibited by the Mak Center for Art and Architecture in Los Angeles in 2010. In the installation, the viewer’s shadow becomes an energized, low resolution image in light on the surface of a scrim covering all four walls and the ceiling.  The simultaneous action of the individual cells demonstrates the indexical nature of photography by abstracting the form and motion of the body in real time.  As the viewer moves, her image appears to become more resolved due to the increased activation of lights on the surface of the room – a physical and perceptual process that emphasizes the reciprocal relationship between the central light and the light sensitive surface. The presence of other people in the room clarifies this effect, allowing viewers to observe the continuity between the projected images and the illuminated shadows without the self-awareness caused by their own activity.