related to the blood
supply of the brain. Here belongs also the ergograph, which gives the
exact record of muscular work with all the influences of will and
attention and fatigue, the automatograph which writes the involuntary
movements, especially also the galvanoscope which may register the
influence of ideas and emotions on the glands of the skin, and thus lead
to an analysis of repressed mental states, and hundreds of other
instruments which are used in the psychological laboratory.

Yet it would be misleading to think only of complex apparatus when
experimental psychology is in question. An experiment is given whenever
the observation is made under conditions which are artificially
introduced for the purpose of the observation. Thus there is no need of
the physical instrument. If I bring a spoonful of soup to my mouth at
dinner and I become interested in the combination of warmth sensation
and touch sensation and taste sensation and smell sensation, then I have
performed an experiment if I take one more spoonful of soup just for the
purpose of the observation. The physician too may carry out important
psychological experiments, without needing the outfit of a real
laboratory. Association experiments, for instance, promise to become of
steadily growing importance. To make them serviceable to the problems of
his office, nothing but a subtle psychological understanding is needed,
inasmuch as any routine work schematically applied to every case alike
would be utterly useless. Give your man perhaps a hundred words and let
him speak the very first word which comes to his mind when he hears the
given ones. You call rose, and he may say red or flower or lily or
thorn; you call frog and he may answer pond or turtle or green or jump,
and if you choose your hundred words with psychological insight, his
hundred answers will allow a full view of his mental make-up. This is an
experiment which does not require any instruments at all but a man's
subtle analysis of the replies. That is not seldom sufficient to secure
the diagnosis of complex mental variations. The method yields still more
if the time for such a reply is measured, but there again not the costly
chronoscope of the laboratory is indispensable; a simple stop watch
which gives the fifths of a second would be fully sufficient for all
practical purposes. From such simple facts of the mental inventory the
association experiments may lead to complex questions which slowly