I made was the proper
one. And yet she, too, soon fell into line in the matter of executing
unconsciously the characteristic head movements. In a total of 50 tests,
I was able to make 10 correct guesses in the course of the first 20
tests, 8 in the next 10 tests, and 19 in the last 20 tests. Miss von L.
noted only a few of her upward head-movements, viz.: those that were
especially pronounced (movements through about 2 millimeters), but of
the others she knew nothing. The same experiment was repeated with a
psychologist, well-trained in introspection, as a subject. Success was
even greater here. But no matter how closely the subject observed
himself, he was unable to solve the puzzle.

Variations which were introduced in these tests, I will only mention in
passing. Thus, instead of making an arm movement, I, in some cases,
would tap with my foot, for "Ibis" once, for "Kiebitz" twice. The
subject could not see my feet. The involuntary movement-expression which
became associated with "Ibis" was one nod of the head, with "Kiebitz"
two nods, etc. Here our only concern was to show that unconscious change
in natural expressive movements and the acquisition of artificial ones
are possible in the case of psychically normal subjects trained in
introspection.

I was not satisfied with convincing myself subjectively of the facts
indicated, but sought to fix them objectively, by means of a graphic
method. For this purpose I used the device mentioned by Prof. R. Sommer
for the analysis of expressive movements.[18] The purpose for which
Prof. Sommer's apparatus had been constructed, was to record the
involuntary tremor and movement of the hand. These movements, of course,
take place in the three dimensions of space. By means of three levers it
is possible to record the movements upon the flat surface of a smoked
paper fastened to the revolving drum of the kymograph, the movements in
each direction being recorded by a separate lever, in such a way that
the three curves thus made represent the analysis of a single movement
into its three dimensional components. By making slight changes, which
tended to complicate the experiment somewhat, I adapted the apparatus to
the measurement of movements of the head. The method of experimentation
was the following. The subject whose movements were to be registered,
was placed in the device in such a way that his trunk and head were bent
slightly forward, the latter a little more than the former.