[en] Transient light-induced absorption changes α_li(t), caused by optically generated small polarons, are investigated in LiNbO₃:Mg below and above the optical-damage-resistance threshold (ODRT). The lifetime of α_li(t) is reduced by three orders of magnitude above the ODRT while a significantly enhanced amplitude α^max_li is observed in the infrared. Our observations are in full accordance with the predictions of microscopic models for the ODRT, namely the removal of Nb_Li antisite defects upon incorporation of Mg ions, and an enhanced dark conductivity. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (Abstract Copyright [2008], Wiley Periodicals, Inc.)