Weber-Fechner law

[vābər-]
n.
  1. The principle that the intensity of a sensation varies by a series of equal arithmetic increments as the strength of the stimulus is increased geometrically.Fechner-Weber law
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.