Indices of the light-adaptation process in the human visual system were obtained by means of both the electroretinogram and a psychophysical incremental threshold procedure. The process was studied for the time interval between 1 sec. and 15 min. after the onset of adaptation. The form of the electroretinal adaptation curve was found to depend upon the stimulus area conditions and was different for the positive and negative components of the electroretinogram. The psychophysical sensitivity curves all showed a tendency to decrease after 3 min. in the light. "The results are of significance for visual theory." (PsycINFO Database Record (c) 2006 APA, all rights reserved)