The Measurement of Discriminability
Etienne Grossman · Quarterly Journal of Experimental Psychology · 1955
Abstract The need for a quantitative measure of “Discriminability” is pointed out. A formula is required which will enable one, knowing the physical measurements of a set of sensory signals, to predict the time taken by a human observer to recognize any one. Existing formulae relate to the two-choice threshold task and to very “easy” multi-choice ones. A more general treatment is attempted in order to cover the region between these two special cases. For the limited case of two-choice one-dimensional signals, three functions fulfilling the requirements have been derived from theoretical considerations and tested against observed times for visual and proprioceptive sorting tasks of various levels of “difficulty.” The function: was chosen as fitting the data most adequately, and has been named the Confusion-function. A method of extending its use to multi-choice and multi-dimensional signal-sets is outlined and experimental results concerning the former are presented. The relation between this function and ...