. A true final jerk does not occur, we note
rather in all three curves registering the head movements, slight
time-marking movements, especially in the second curve. In the third
curve they are at first minute, but increase steadily in size until the
fourth tap, after which they suddenly disappear. The subject had, as a
matter of fact, thought of the number 4, but it is hardly probable that
Hans would have reacted properly upon these stimuli.

[Illustration: FIG. 12.]

Mr. Schillings had thought of the same number in all three tests given
in figures 10, 11 and 12. The probabilities are that if he had been
working with the horse at the time, in the first case Hans would have
reacted with three taps with the right foot and a final tap with the
left, as a result of the questioner's bending forward again after the
premature head-jerk at 3. In the second instance the horse would
probably have given four taps with the right foot, and in the third, the
chances are that he would have continued to tap beyond the 4.

These curves give, on the whole, a fair idea of the intensity and of the
course of attention of the various subjects.

Let us now consider a number of records which illustrate the expressive
movements involved in the process of thinking of such concepts as "up",
"down", etc. Their arrangement is identical with the scheme given in
figure 5, with the exception that the tapping curves (the sixth and
seventh) do not appear. The subject was asked to think of any of the
words "up", "down", "right", "left", "yes", "no", etc. He was to begin
to conceive them vividly when the command "Now!" was given. This moment
is recorded in figures 13 to 15 on the fifth curve. What has been said
on page 123 with regard to respiration, holds also in these instances:
only the first rise recorded in figure 14 can be regarded as normal.
The magnitude of these movements varies between 1/2 and 3 millimeters.
The records of the subject whose movements were most extensive, show an
average of 1-7/10 millimeter (based on 50 tests), with a mean variation
of 6/10 millimeter. Lack of space precludes the reproduction of more
than three records.

Figure 13 (von Allesch) shows the movement accompanying the thought of
"up", a slight raise of the head, recorded in the fourth curve. (The
thought of "down" is accompanied by a corresponding downward movement.)

[Illustration: FIG. 13.]

Figures 14 (von Allesch) and 15 (von Manteuffel) illustrate the no