sees the lips of the patient
moving. He is thus able to examine not only the involuntary choice of
association but also the time of every associative process. But a second
condition ought also to be fulfilled. After some indifferent words,
others ought to be mixed into the series which touch in a tentative way
on various spheres corresponding to the possible suspicions. The groups
to which the hidden thoughts of psychasthenics, for instance, belong are
not many. As soon as our series of words strikes such a group, the
reaction of the mind may be discriminated. The effect may be a general
perturbation resulting either in an unusual delay of the fitting
association or in an effort to cover the sore spot by an unfitting
association. Sometimes the dangerous association may rush forward even
with unusual rapidity but, as soon as it is uttered, it gives a shock to
the mental system, brings the whole associative process into disorder,
and the result is that the next following associations are abnormally
delayed. The skilled psychologist will quickly take such a change as a
cue for the selection of the later words in his series. Of course, he
will at first return to neutral words, but as soon as he has found a
danger spot, he will approach it from various sides, perhaps in every
fourth or fifth word, and may then find out which particular experiences
are disquieting the patient. Words like women or money or career or
family or disease are often sufficient to get the first inkling of a
mental story.

With less diagnostic elegance we sometimes reach the same end by taking
careful records of pulse and breathing and involuntary movements during
an apparently harmless conversation. The instruments at the disposal of
the psychologist are those familiar to every psychological laboratory:
the pneumograph, which registers the movements of respiration; the
sphygmograph, which writes the pulsation of the artery in the wrist; the
automatograph, or other instruments, which register the slight
unintentional movements of the arm. If the examiner is skillful, he will
not fail to discover the changes in breathing and pulse and reaction as
soon as the painful groups of ideas are approached. More of theoretic
interest and too cumbersome for practical diagnosis is the unfailing
galvanic reaction from the skin in which the glands change their
activity and their resistance to the galvanic current under the
influence of hidden emotions. Yet all thes