Question

Psychophysics began with the work of which 19th-century german scientist(s)

Answer 1

Psycho-Physics as a discipline within the psychology began with the work Elemente de Psychophysics ( Elements Of Psychophysics ), written by German philosopher and physicist Gustav theodor Fechner. He actually aimed at developing a method that relates mind ( psych ) to matter ( physics ).  So Psychophysics is the  scientific study of the relation between stimulus and sensation.