Fechner’s law states that the sensation potency increases as the stimulus intensity logarithm likewise increases. This is specifically illustrated with the formula: Ψ = k logS. “Ψ” pertains to the perceived psychological intensity, “k” is a constant in connection with a certain sensory modality, and “S” is the actual physical intensity of the stimulus which is measured by an appropriate device. The mathematical formula implies that large changes in physical stimuli may be needed for it to be psychologically perceptible. This was formulated by Gustave Fechner (“insert link”), a German philosopher, physicist, and experimental psychologist.