We rederive the refractive effects of neutrinos as the interference of coherent scatterings. We study the details of this approach, including the features of wave packets, the possible effects of the recoil of the scatterers, the thermal motion and the polarisation of the matter. Our calculations demonstrate how the coherence is lost whenever there is an observable change in the scatterer state. Particularly, flavor changing dispersive effects are found to be smaller than previously claimed. For a degenerate medium the scattering model suggests a suppression of the refractive effects.