t the results of the reaction
experiments agreed with his independent decision as to his mental
type.

In none of the cases did this correspondence fail, although all were
not so pronounced in their type preferences as was Mr. C.

The second part of the research had in view the question whether
reaction times taken upon speech would show the same thing; that is,
whether in Mr. C.'s case, for example, it would be found that his
reaction made by speaking, as soon as he heard the signal or saw the
light, would be shorter when he paid attention to the signal than when
he gave attention to his mouth and lips. For this purpose a mouth key
was used which made it possible for the subject simply by emitting a
puff of breath from the lips, to break an electric current and thus
stop the chronoscope as soon as possible after hearing the signal.
The mouth key is figured herewith (Fig. 6).

[Illustration: FIG. 6.--Mouth-key (Isometric drawing) The metallic
tongue E swings over the mercury H, making or breaking the circuit A H
E D B or C E H A. The tongue is moved by a puff of air through the
funnel F. (Devised by Prof. W. Libbey.)]

This experiment was also carried out on all the subjects, none of them
having any knowledge of the end in view, and the experimenters also
not having, as yet, worked out the results of the earlier research. In
all the cases, again, the results showed that, for speech, the same
thing held as for the hand--namely, that the shortest reaction times
were secured when the subject paid attention to the class of images
for which he had a general preference. In Mr. C.'s case, for example,
it was found that the time it took him to speak was much shorter when
he paid strict attention to the expected sound than when he attended
to his vocal organs. So for the other cases. If the individual's
general preference is for muscular images, we find that the quickest
time is made when attention is given to the mouth and lips. Such is
the case with Mr. B.

The general results go to show, therefore--and four cases showing no
exception, added to the indications found by other writers, make a
general conclusion very probable--that in the differences in reaction
times, as secured by giving the attention this way or that, we have
general indications of the individual's temperament, or at least of
his mental preferences as set by his education. These indications
agree with those found in the cases of aphasia known as "motor,"