Weber-Fechner law

Weber-Fechner law is a law of psychophysics proclaimed by Ernst H. Weber (1795-1878), stating that the least noticeable increase in the intensity of a human sensation is always brought about by a constant proportional increase in the previous stimulus. Gustav T. Fechner (1801-1887) developed this into the Weber-Fechner law that to increase the intensity of a sensation in arithmetical progression, it is necessary to increase the intensity of the stimulus in geometric progression.