Under the influence of an applied electric field, dipoles reorientate to provide most of the index contrast of holograms in photorefractive polymer composites. The poling transient is commonly described by modified exponential functions. Either a KWW stretched exponential or a bi-exponential function is required to fit adequately the observed behavior. Moreover, when the analysis was performed for data that extended over 3 orders of magnitude in time then at least 5 time constants were required. We show that the dispersive rotational dynamic is, in fact, described by a power law, and hence does not have characteristic lifetimes. The dispersive rotation of dipoles is described simply and accurately using a time-dependent diffusion coefficient. This gives an excellent agreement between theory and measurement. This has important implications for the characterization of the transient response of any electro-optic process or device based on the rotation of dipoles in a dispersive amorphous material such as a polymer or glass.