Biology Reference
In-Depth Information
with no counterpart in physiology. (See Helmholtz's,
1911
, vol. III,
pp. 24-29, discussion on how inductive conclusions, unconsciously
formed, may influence perception.) Willmer's (
1946
) theory represented
a radical break with these ideas. Thus, he made rod-cone interaction
at the retinal level a central part of his theory. This strong emphasis
on rod-cone interaction in the nervous system was also advanced by
Saugstad and Saugstad (
1959
). The change in focus is clearly revealed
when von Kries's (
1929
) classical review of the duplicity theory is
compared with the evaluation of the theory given by Saugstad and
Saugstad (
1959
) 30 years later. While Saugstad and Saugstad made
the concept of rod-cone interaction in the retina their central point of
discussion, the concept of rod-cone interaction was barely mentioned
by von Kries.
9.2 Saugstad and Saugstad: Evaluation of
Schultze's duplicity theory
The paper of Saugstad and Saugstad (
1959
) represents a painstaking
attempt to review and evaluate all major evidence for and against
the duplicity theory. Indeed, it may be considered the most thorough
evaluation of the empirical basis of the theory ever made and will,
therefore, be dealt with in some detail. Previous reviews had been
published by Hecht (
1937
) and Lythgoe (
1940
).
9.2.1 Reformulation of Schultze's duplicity theory
Saugstad and Saugstad (
1959
) considered Schultze's (
1866
) formulation
of the theory vague and inexplicit. They therefore found it necessary,
before evaluating the theory, to reformulate its basic assumptions to
make the implicit meaning clearer.
Firstly, they interpreted Schultze's (
1866
) theory to mean that
rods did not,
under any condition
, mediate chromatic vision. This
reformulation, of course, highlighted the controversy between the
orthodox duplicity theory and the suggestions of König (
1894
) and
Willmer (
1946
) that rods, under certain conditions, generated a blue
colour sensation.
