ABSTRACT
Integration psychophysics differs from classical psychophysics in a fundamental way—in the difference between psychophysical law and psychological law. Classical psychophysics sought for simplicity and order at the interface of the physical and psychological worlds. Fechner’s claim that the two worlds were related by an exact mathematical function gripped the imagination of all his successors. But this concept of psycho-physical law remained controversial and uncertain; the scope of classical psychophysics was too narrow to support a solution to its own central problem.
