Weber’s Law or Fechner’s law or the Weber–Fechner law

Weber’s law is a principle law in psychophysics first proposed by Gustav Weber, and further formulated by his student Gustav Fechner. The law states that the difference in perceptual sensitivity to a stimulus is inversely proportional to the actual difference. In other words, if a person lifts objects of differing weights, his or her perception of the difference in weight show a uniform ratio as the weight is increased or decreased.