The American Journal of Insanity

I. THE EXPERIMENTAL CRITERION OF RETARDATION.
Our reaction to a given situation is determined by the lines of
least resistance in the nervous pathways at that moment and to
that stimulus. This “set” of the nervous system is determined
essentially by the various impulses that have traversed it before,
and by immediate conditions of nutrition. These factors give a
series of lines of least resistance to an indefinite number of situa-
tions, and the reaction to any of these situations will be along the
line of least resistance which the past history of the individual
has determined for it. The factors which go to determine these
lines of least resistance are normally and naturally selected in
such a way as shall be most beneficial to their possessor. It is
apparent how largely the teleological character of our behavior
depends upon the maintenance of the fine balance in the nervous
pathways in favor of the most advantageous series of responses.
One can also readily figure the profound disorder of behavior
inevitably resulting from any disturbances of this "neural bal-
ance," be these disturbances themselves the ultimate products of
intoxication, or of faulty habits of action and thought.

In a fundamental retardation we have an agency or number of agencies, presumably of toxic origin, which tend to increase the difficulty with which certain nervous impulses, consequently certain psychic functions, can proceed. The actual study of cases shows us that the symptom of retardation may involve the various mental functions largely independently of one another. When its manifestations occur mainly in the higher, associative processes of the mind, we speak of it as a “ difficulty in thinking' or “thinking disorder ”; we may also see its phenomena confined with some definiteness to the motor side; and as has been elsewhere suggested, those manic-depressive states which show an emotional condition of apparent apathy in contradistinction to depression are the manifestation of this same symptom in the affective sphere. In like manner we may find these phenomena even more restricted within the categories mentioned.

It is obvious, however, that in merely speaking of a greater difficulty ” of the nervous processes, we do not tell the whole story of the effect of this difficulty upon the resulting movements, which are, of course, our ultimate criteria of the symptom. The response may be merely delayed, without seeming to be otherwise affected. More often, however, there is coupled with this delay a certain weakening of its force and effectiveness. On the other hand, the response may be long delayed and then come with explosive force, as though the patient had been gradually accumulating sufficient energy to burst through the retardation. Occasionally the response fails entirely, apparently from not being strong enough to break through; this is apt to be the case with indifferent situations. Under great stresses, however, a marked retardation may be entirely swept away, indicating a considerable reserve strength of the voluntary impulse, just as our muscles seldom if ever put forth under voluntary stimulation the effort of which they are physiologically capable.

Clinically, we judge of a patient's retardation through the general character of his behavior, by the quickness with which he seems to think or speak or move. Experimentally, we make use of the innumerable tests put forward as measures of mental time. So long as we deal only with the presence or absence of retardation in general, the precise mental function that we select to measure is probably of secondary importance to the accuracy of

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The American Journal of Insanity, Volumul 66