УМСТВЕННАЯ ОБСТАНОВКА (№ 10) — Закон Вебера-Фехнера

MENTAL FURNITURE #10 - The Fechner Weber Principle

WEBER-FECHNER PRINCIPLE: An approximate psychological law relating the degree of response or sensation of a sense organ and the intensity of the stimulus. The law asserts that equal increments of sensation are associated with equal increments of the logarithm of the stimulus, or that the just noticeable difference in any sensation results from a change in the stimulus which bears a constant ratio to the value of the stimulus.

In the bright midday sun you light a candle. Does anyone notice it getting brighter? Will you identify my voice if I call you on your cellular phone at a rock concert? You're carrying the downside of a refrigerator up a flight of stairs and someone puts a hammer on the fridge, do you sense the difference? Mostly, the Fechner Weber Principle or Law holds that you won't notice a difference. Moshe Feldenkrais invoked the Fechner Weber Law in discussing the necessity of reducing effort while learning. The Fechner Weber principle marked the beginning of the science of psychophysiology and yet all its implications have not been played out in that field.

Ernst Heinrich Weber (1795-1878) was the German anatomist and physiologist who first introduced the concept of the just-noticeable difference, that is, the smallest difference perceivable between two similar stimuli. Weber was a professor at the University of Leipzig from 1818 until 1871. He is known chiefly for his work on sensory response to weight, temperature, and pressure; he described a number of his experiments in this area in De Tactu (1834;"Concerning Touch"). Weber determined that there was a threshold of sensation that must be passed before an increase in the intensity of any stimulus could be detected; the amount of increase necessary to create sensation was the just-noticeable difference. He further observed that the difference was a ratio of the total intensity of sensation, rather than an absolute figure; thus, a greater weight must be added to a 100-pound load than to a 10-pound load for a man carrying the load to notice the change. Similar observations were made on other senses, including sight and hearing. Weber also described a terminal threshold for all senses, the maximum stimulus beyond which no further sensation could be registered.