Biology Reference
In-Depth Information
Interestingly, Hering speculated that if light could have
activated the assimilation process in the 'white-black' see-substance,
then the experience of black by such a light would have been much
more intense than the most intense black we know of (Hering,
1878
, pp. 88-89), and if a light stimulus could have produced equal
dissimilation and assimilation in this substance alone, that light
would have been invisible (Hering,
1878
, p. 122).
A basic postulate in Hering's colour theory was his assumption
that all six primary material processes were always in operation in
all parts of the see-substance, despite the antagonistic actions of
the dissimilation and assimilation processes (Hering,
1878
, p. 85,
pp. 118-120, and p. 126). The question then arises as to why red and
green, and yellow and blue colours are mutually exclusive at the
conscious level. Hering attempted to resolve this apparent paradox
with his suggestion that dissimilation and assimilation in the 'red-
green' and in the 'yellow-blue' see-substances had relatively low
magnitudes and, hence, low impressiveness.
4.5 Experiments in support of Hering's
colour theory
Besides the phenomenological analysis of the visual spectrum and
the binary colour-mixture experiments, Hering found experiments
on simultaneous and successive contrast, and simultaneous and
successive induction, to be of particular importance in revealing
information on the mechanisms of the underlying material processes
(Hering,
1878
, pp. 95-103, 126-135). Thus, the experimental results
he obtained could all easily be explained by the reasonable assump-
tion that when one of the opponent processes was triggered by a
light stimulus, the relative sensitivity of the antagonistic process
increased with exposure time in the stimulated area and decreased in
the neighbouring area.
As an illustration: when the eye, in a completely dark-adapted
state, is pre-stimulated with a red light in a given retinal area
(dissimilation increases) and, then, successively test-stimulated with
