Despite much experimental and theoretical effort, the electronic and the structural properties of the (4 x 2)/(8 x 2)-low-temperature phase of in nanowires on Si(111) are still under discussion. In our combined experimental and theoretical work we utilize the surface selectivity of reflectance anisotropy spectroscopy (RAS) to analyze the electronic (surface electronic states) properties. The RAS response is directly compared with \emph{ab-initio} density functional theory (DFT)-local density approximation (LDA) calculations of the optical anisotropy of different surface models. (C) 2004 Published by Elsevier B.V.