Biology Reference
In-Depth Information
that at least five different primary retinal processes had to be
postulated in order to account for human colour vision.
For a long period of time, then, the trichromatic colour theory
was a speculative theory without any firm foundation. Eventually,
however, a firm basis for the trichromatic theory was provided by
Maxwell (
1855
,
1860
). Taking advantage of Newton's principle of
gravitation, he demonstrated, in opposition to Helmholtz, that
three primary lights were, in fact, sufficient to match every spectral
colour. Furthermore, in support of the trichromatic colour theory
he demonstrated that protanopes had a reduced form of colour
vision in that they lacked the 'red' receptor system.
In contrast to these four classical theories, Hering's (
1878
)
opponent colour theory was not triggered by facts, but by ideas, i.e. by
Spinoza's famous doctrine of psychophysical parallelism as applied to
vision by Mach (
1865
). Thus, Hering immediately embraced Mach's
psychophysical maxims and made them both the starting point and
basic presumption on which his deductions about brain activities
could be made.
Yet, it is important to note that the psychophysical maxims
of Mach only represented the tool whereby the opponent colour
theory could be built - they did not form any part of the theory per
se. Thus, to develop his theory, Hering also needed an analysis of
the colour phenomena. Here he could take advantage of Goethe's
colour theory - especially Goethe's famous colour circle where
primary colour qualities and opponent interactions could be found.
The development of the opponent colour theory in detail and his
strong conviction that his theory was correct were, however, first
and foremost based on his own painstaking and keen phenomeno-
phenomeno-
logical analysis as regards colour mixing, successive and simulta-
neous colour contrast, and also successive and simultaneous
colour induction.
Given these important features of the development of the
duplicity theory, the question naturally arises as to whether they
