_Photographs taken prior to the experiment._]
The second test added to the reaction tests was undertaken to determine
the steadiness of the subjects. Two brass rods 40 cm. long were held in
a vertical position at a distance of 7 mm. from each other. The subject
took in his right hand a brass rod 40 cm. long and 5 mm. in diameter and
tried to pass the end of this rod up and down between the vertical rods
without touching them. The subject’s relation to the vertical rods may
be further defined by saying that he stood directly in front of them
and reached out nearly at arm’s length. The vertical rods were at about
the height of his chest. In order to get a record of the accuracy with
which the subject moved the hand-rod up and down without touching the
vertical rods, the vertical rods and the hand-rod were connected with the
two poles of an electric circuit. Whenever they touched they closed the
circuit, and a marker placed in the same circuit recorded the fact on a
smoked paper record. The time was recorded in parallel with this record,
so that any long continued contact could be measured. For the most part,
contacts were only of very brief duration. In reporting the results of
this test, every contact made while passing the rod once downward and
once upward is counted as at least one. Continued contacts are recorded
as two, three or more, according to the period of duration. Where there
are such added counts because of continued contacts, a second quantity
is given in the tables after the first. This second quantity, which is
enclosed in parenthesis, indicates merely the number of contacts without
reference to whether they are long or short.
No special comments are necessary to explain the tables. Tables 1-5
report in sigmas, or thousandths of a second, the average time of ten
reactions on the date, and for the subject, indicated. In the third
column, is the mean variation for the series of ten reactions.
Table 6 shows the general averages by the month for a given individual,
and in the sixth column the general average of all the determinations for
each reactor. The fourth column in each of the earlier tables shows how
much the results of a given day vary from the final general average. All
the tables give, at the bottom, group averages whenever the full series
is present.
Table 7 gives the number of taps executed in ten seconds at each
successive test. The dates are not given in detail, but are the same as
those of the reaction tests.
Table 8 gives the monthly averages of taps.
Table 9 presents the results of the steadiness tests.
The three sets of results, namely, those from reaction, tapping, and
steadiness, differ from each other. On the whole, the reactions grow
longer; the tapping varies, but shows neither decided improvement nor
deterioration; while steadiness improves very decidedly.
The comment made on the results obtained with the soldiers applies here
so far as the reaction tests are concerned. These tests were not repeated
with sufficient frequency to reduce the reaction to automatic performance.
The tapping is such a simple performance that improvement is not to be
expected. The absence of any general improvement or deterioration argues
for an absence of any general nervous change in the reactors.
The improvement in steadiness is in part at least, probably in very large
measure, due to the fact that the subjects became more familiar with the
test and approached it with less of the embarrassment which attends a new
and unfamiliar test.
The lengthening of the reaction times indicates a less intense
concentration of the subject upon the work in hand. The slightest
relaxation of attention puts the subject behind in responding to the
signal. It was clear to superficial observation, especially in certain
individual cases, that the subject was giving less attention in the
later experiments. This lack of concentration is not obviously related
to the changes in diet. Indeed, the fact that no corresponding falling
off appears in the tapping would seem to argue that the lack of attention
in the reaction tests was not due to deep-seated nervous conditions, so
much as to growing impatience on the part of the reactors with the ordeal
of being tested. The tapping experiment is less likely to be affected by
lack of interest on the part of the subject, because here the subject is
called upon to be constantly active, and there is no such opportunity
for attention to lapse as is furnished by the intervals which intervene
between successive reactions. The tapping is accordingly perhaps the best
series on which to base final judgment as to the nervous condition of the
men. Here, there appear the variations which show in any ordinary series,
but there is no steady improvement through growing familiarity with the
test, nor any laxness of attention to produce relatively unfavorable
results.
Mr. Steele and Dr. McAllister are largely responsible for the actual
collection of the data on which this report is based.
(Signed) C. H. JUDD.