Note on luminous flux discrimination in monkey and man

Subjects were instructed to equate the brightness of two stimuli of different areas presented alternately to the far periphery. The results are closely describable by IA = k (Ricco's Law), indicating that the subjects equated total luminous flux. It is suggested that these results and certain other behavioural and anatomical considerations make it unnecessary to consider flux discrimination a “subcortical” or “lower” visual function as compared with brightness discrimination.