IV. Tests with smoked paper on the floor were
now alternated with tests in which the floor was plain.
The alternation was rendered necessary by the fact
that the paper was laid over the electric wires and
therefore prevented the punishment of mistakes.
The purpose of these tests was to discover whether
the smoked paper, which was an essential condition
for the next test, was itself a disturbing condition.
These tests were continued until the animal had followed
the path correctly, despite the smoked paper, twice
in succession.
V. The electric lights were now turned out and tests
were given in total darkness, with smoked paper on
the floor as a means of obtaining a record of the
number of errors. These tests were continued until
the path had been followed once correctly.
VI. The labyrinth was now thoroughly washed with
warm water, to which a little kerosene had been added,
and quickly dried over a steam radiator. This
usually necessitated a delay of about five minutes.
As soon as the labyrinth was dry, tests were given
to discover whether the odors of the various passages
had been serving as important guiding conditions.
These tests were continued until the path had been
followed once without error.
VII. A final test in darkness completed the series.
As it was not possible for the observer to watch the
animal and thus to count the number of mistakes which
it made in total darkness, the simple method of placing
a piece of smoked paper on the floor of the labyrinth
was used. The mouse left a graphic record of its
path on the paper and from this the number of errors
could be ascertained. In the tests now to be
described the smoked paper was placed upon the electric
wires, but later a form of electric labyrinth was
devised in which it was underneath and therefore did
not interfere with the electric shock.
The above series of tests was given under the same
external conditions in a dark-room to six pairs of
dancers. In all cases, two individuals, a male
and a female, which had been kept in the same cage,
were experimented with at the same time, i.e.
one was permitted to rest in the nest-box while the
other was being put through a test. This was done
in order that the comparison of the results for males
and females should be perfectly fair.
The detailed results of this long series of tests
may be presented for only two individuals, Nos. 210
and 215, Table 33. In this table lines separate
the results of the seven different kinds of tests.
THE ROLE OF SIGHT, TOUCH, AND SMELL IN LABYRINTH EXPERIMENTS
No. 210
No. 215
TEST CONDITION ERRORS
CONDITION ERRORS
I. 1 No shock 9
I. No shock 2
