As part of some graduate research I am doing, I need a function that
describes the relationship between the intensity of a physical stimulus
and subjective psychological magnitude. The outdated Introductory
Psychology material that I have (from the 1970s) talks about Fechners
Law and Stevens Power Function. It indicates these laws as follows:
Fechners Law: S = K log I
Stevens Power Function: S = I (to the K exponent)
where S is psychological magnitude, K is a constant particular to the
continuum, and I is the intensity of the physical stimulus.
The text says that there are problems with both of these functions, but
that the evidence is leaning toward Stevens Power Function.
My question is: what is the current thinking about the relationship
between physical and psychological magnitude of stimuli? Has either of
these functions been accepted? Are there new ways of thinking about
Any feedback from knowledgeable people or psychophysics gurus will be
regarded as near live saving information!
My e-mail is davis at intr.net. My fax is (202) 965-7879.
Many thanks in advance!!
--Michael Sean Davis