The research activity is an attempt to define functional relationships that occur between the reception of light stimulation, the routing of the information to neural centers, and the expression of that information in visual behavior. The research uses techniques of behavioral conditioning, electrophysiology, and absorption spectroscopy to define reactions of the organism to light. The project correlates visual pigments uncovered by microspectrophotometry with single unit electrical changes in the visual system induced to paramenters of light stimuli. The neural responses to light are then correlated with behavioral data for appropriate threshold functions. The work is being carried out on two animals, the turtle and pigeon. Both these animals have cone-dominated vision and these structures are presumably instrumental in color discrimination and information processing.