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**Psychophysics** studies the relationship between the physical characteristics of stimuli and the psychological experience of those stimuli. Gustav Theodor Fechner, a German physiologist, philosopher, and physicist, is considered the father of psychophysics and published a seminal work titled "Elements of Psychophysics" in 1860. This foundational text outlined his experimental methods and the Weber–Fechner law, a mathematical relationship between the intensity of a stimulus and the perception of that stimulus.