Psychophysics is the branch of psychology dealing with the relationship
between physical stimuli and their perception. While the majority of research
has been done on vision, the discipline covers all the senses; papers
have even been published on extrasensory perception, although more prosaic
alternatives like hearing, taste, touch (including skin and enteric perception),
and smell are the more prevalent.
Psychophysics studies psychological scales for physical stimuli. Hot
and cold, for example, are psychological scalings of temperature stimuli
for which such physical measures as degrees celsius provide only physical
Areas of investigation include sensory thresholds, methods of measurement
of sensitivity, and signal detection theory.