GUSTAV FECHNER (1801-1887)

• Fechner, was the son of a Lutheran minister. His father died when he was a child (5).
• He spent his entire academic career, as a student, teacher, and researcher, at the University of Leipzig.
• He first went through medical school, and was interested in physiology, and then in physics, later in psychophysics, esthetics and philosophy.
• In the course of things, he became  interested in studying afterimages.
  In so doing, he damaged his eyes looking at the sun (around 1840).
  Hence, his eyes were hypersensitive, and he had to stay in a darkened room. This state of affairs went on for a long time, was accompanied by depression, and a lot of time spent reflecting.

Fechner's dilemma

• Fechner had also become depressed because of the materialism (nightview) of his day.
• He turned his interest to philosophy (dayview). 
• For 25 years, in addition to his "normal" scientific writings, he also wrote satirical works under the pseudonym of "Dr Mises" to push his dayview and show the absurdity of materialism. The first one of those was written in 1821, when he was still a student.
• Fechner was a PANPSYCHIST and believed that all the universe is conscious. He can be considered to be a SPIRITUAL MONIST because he expalins everything in terms of the spiritual dimension.

Fechner's breakthrough (1850)

• Fechner was the founder  of the field of psychophysics.His Elements of Psychophysics were published in 1860.
• He "rediscovered" Weber's notion of differential threshold
• He formalized Weber's law and saw it as a way to unite body and mind (sensation and perception), bringing together the day view and the night view, reconciling them.
• Fechner saw this as a major breakthrough,
  • as a solution to the body-mind problem.
  • as a way to make psychology a science

  This is how it works:

• Differential threshold= just noticeable difference (jnd):someone can tell the difference between two stimuli 50% of the time.
• Weber's law: S2-S1/S1=K         
  • Where S1 is the base stimulus
  • Where S2-S1= the jnd upward from S1
  • K is a constant. That constant is different for each type of stimulus (ex: light, sound, weight)
• Weber's law relates sensation and perception
  • The jnd (which is a perceptual judgment)
  • and the intensity of the base stimulus (which is a physical fact) are related through the constant K.
• This is a mathematical relation
  The experienced sensation (P) is related to the magnitude of the base stimulus through a logarithmic relation of the form: P=Klog S. Thus the stimulus moves according to a geometric progression, while the perception moves according to an arithmetic progression.
• If the perceptual world (mind) is mathematically related to the material world, then
  • psychology, which concerns the mind, can become a science, since the mind can be studied through physical measurement etc...
    • Hence, Fechner created the field of psychophysics, in which he broadened his study of thresholds (both absolute and differential), and of other perceptual phenomena.
    • He also is the founder of the field of esthetics, looking at how esthetic judgment is made (i.e.as a matter of proportions)
  • a scientist does not have to give up his/her beliefs in the mind, and in the spiritual realm to be a scientist, since things of the mind can be studied through physical phenomena to which they are mathematically related.