Biology Reference
In-Depth Information
5
The colour theories of Armin
Tschermak and George Elias
Müller
5.1 The colour theory of Tschermak
In developing his own colour theory, Tschermak (
1902
,
1929
) made
a critical evaluation of the colour theories of Young-Helmholtz,
Schultze and Hering. With regard to Young-Helmholtz's colour theory,
he was severely critical. Thus, he asserted that the basic assumption
of three independent, primary colour-related processes postulated by
the trichromatic theory could not be reconciled with the phenom-
enological analysis of colour sensation that revealed
six
qualitatively
different unitary sensations: red, yellow, green, blue, white and black.
It would, for example, be impossible to give an adequate explanation
of the uncompounded yellow-related material process by green- and
red-related processes, or the uncompounded white-related process by
red-, green- and violet-related processes. Also, in opposition to the
trichromatic colour theory, experiments on colour mixture, colour
induction and colour contrast clearly revealed opponent interaction
processes going on in the visual system.
Finally, in accord with von Kries (
1911
), Tschermak (
1902
,
1929
) pointed out that the basic assumption of the trichromatic
colour theory, that white sensation was generated when the three
different types of cone receptors were activated to about the same
degree, was seriously challenged by the fact that colourless sensation
could also be observed in scotopic vision where only rod receptors
were known to function.
With regard to Schultze's duplicity theory, on the other hand,
he found the evidence strongly in favour of its basic assumptions that
cones functioned in day vision giving rise to both achromatic and
chromatic sensations, and that rods functioned in night vision, giving
