Analyses of the electronic absorption spectra and their polarization spectra of the radical anions of permethylated hexa- and octasilane and poly(cyclohexylmethylsilane) in the mixed solvents of nonpolar methylcyclohexane and polar 2-methyltetrahydrofuran at 77 K have revealed that the orbitals of the excess electrons in the radical anions are antibonding pseudo-pi composed of Si 3p(y) atomic orbitals bisecting the Si-Si-Si planes. The near-IR and UV bands of the radical anions are assigned as being due to the excitation of an electron from the SOMO pseudo-pi(3p(y)) to pseudo-pi(3p(y)) and from the HOMO pseudo-pi(3p(x)) to antibonding-sigma(3s), respectively. The near-IR band of the polysilane radical anion shows strong solvatochromic shift, which arises from the localization of the excess electron on a part of the main chain. Localization of the excess electron is proposed to be due to Anderson localization which is induced by the fluctuation of pseudo-pi conjugation arising from the irregularity of the torsional angles of the Si-Si bonds.