Who identified the just-noticeable-difference (JND) that relates to Weber's Law?

The concept of the just-noticeable-difference (JND), which is integral to understanding sensory perception, is attributed to Ernst Weber. He formulated what is now known as Weber's Law, which states that the smallest change in a stimulus that can be detected (the JND) is a constant proportion of the original stimulus. This principle highlights the relationship between the intensity of a stimulus and the ability to perceive changes in that stimulus, which is fundamental in the study of psychophysics.

Understanding Weber's Law helps explain how we perceive differences in various stimuli, whether it be weight, sound, or light. For instance, if you hold a heavy weight, a much larger increase is needed for you to notice the difference compared to a lighter weight. This principle is crucial in fields such as psychology and sensory science, helping to quantify our sensory experiences.