During the past decade intensive work by psychologists, physiologists, and
ophthalmologists has shown that the human electroretinogram (ERG) is a result of two basic
forms of response—scotopic and photopic. The differentiation of these two components has
been achieved through the study of the ERG in normal, color-blind, and night-blind subjects,
under different states of adaptation, with stimuli of varying wavelengths and intensities. The
scotopic and photopic components of the human ERG are similar in that each consists of a …