A two-state model of simple reaction time

A. The Power Law.
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Many authors adopted power functions as psychophysical functions,
which relate subjective time to physical one. Ekman(1958)
proposed the model, which determined the exponent by the method
of fractionation. In the method of fractionation, the subject is
instructed to adjust a variable stimulus so that it appears
subjectively equal to a certain fraction of the standard, usually
half the standard. Ekman(1958) set the power function as
eq.(3-1),
(3-1)
where R (or S) is a subjective (or physical) scale of time, C is
a constant related to the unit of measurement of R, So is a kind
of absolute threshold, and n is the exponent determining the
curvature of the function.
When the subject adjusts the variable stimulus to a value,
S , which, subjectively, is p times that of the subjective value
p
of the standard, S,
(3-2)