Allison Pappas is a fifth-year doctoral candidate in the Department of History of Art and Architecture, studying the history of photography. Her dissertation, “‘Considered only in its ultimate nature’: Photography between Object and Idea,” explores the conceptual frameworks through which we come to think about the medium in a certain way. Its chapters address predominant theoretical assumptions—the photograph’s causal or “indexical” character, its registration of time, its mechanical representation of vision, and its definition by analogy—through examination of photographic experimentation with light, scientific and artistic, that illuminates the medium’s elemental physical attributes. Unfolding from the 1830s to the present, each historically specific case study interrogates the development of particular processes and photographs in relation to a network of ideas, individuals, materials, and technologies, demonstrating how conceptions of the medium repeatedly come into being in an active and extended process. She proposes a dialogic model in which the ideas used to make sense of photography are actively formed in relation to the material photograph itself.