Functional measurement and psychophysical judgment.

Functional measurement theory is applied to four experimental situations in psychophysical scaling. Two judgment models are considered: additive and multiplicative. These are first applied to a psychophysical averaging task and to a ratio estimation task in which the numerical response is assumed to be a valid and proper measure of subjective magnitude. It is shown that factorial designs and analysis of variance procedures not only provide tests of the models but also scales of the independents, stimulus variables.