" 5. Differentiation is easiest to make when the stimulus is smallest. In Awareness Through Movement, Feldenkrais wrote, “If I raise an iron bar I shall not feel the difference if a fly either lights on it or leaves it. If, on the other hand I am holding a feather, I shall feel a distinct difference if the fly were to settle on it. The same applies to all the senses: hearing, sight, smell, taste, heat, and cold.” If a sensory stimulus is very great (say, very loud music), we can notice a change in the level of that stimulus only if the change is quite significant. If the stimulus is small to begin with, then we can detect very small changes. (This phenomenon is called the Weber-Fechner law in physiology.) "

― Norman Doidge , The Brain's Way of Healing: Remarkable Discoveries and Recoveries from the Frontiers of Neuroplasticity