CHAPTER VIII
Summary and Conclusions

The information obtained about Correlations, Practice and
Diurnal Variations can not very conveniently be treated in a brief
summary. This chapter will accordingly deal only with the main
problem of the experiment. This study was undertaken primarily
to investigate the supposed effect of air of low relative humidity
upon nervousness as shown by defective motor control, and upon
general inefficiency in work similar to that performed in daily life
by clerks in offices and operatives in factories. Since tests can not
be given often enough to obtain reliable measures of a changing
condition without having the influence of the variables obscured
by practice, the following device was adopted to balance out the
practice effect. Subjects were tested in squads for a fortnight
each. The first squad spent its first week under the wet, its second
under the dry condition. The second squad spent its first week
under the dry, its second week under the wet condition. For each
test an average for performance in the wet weeks was obtained by
adding the first week of Squad A and the second week of Squad B.
A similar average for the dry weeks was obtained by adding the
remaining weeks. By averaging the data from a number of squads,
half of which were at the beginning, and half at the end of their
practice curve, the practice was pretty well eliminated. Any re¬
maining difference between the wet and dry averages might then
be attributed to the ventilation condition.

Tests of:

Addition                               Arm Steadiness

Aiming                                 Mirror Tracing

Hand Steadiness                  Industrial Fatigue

Tapping                               Reflex Wink

Typewriting                         Eyehd Tremor

were given twice or three times a day in accordance with a fixed
schedule, with 75° F., 50 per cent, relative humidity, and 75° F.,
20 per cent, relative humidity as the air variables. In all of these
tests the average performance computed as described above, and
also the average improvement from the first to the last trials on
any particular day, showed no reliable difference. That is, by
these tests of nervous and motor control and by the more purely
intellectual tests we could detect no infiuence of excessive dryness
during two weeks' exposure or during the working day.    While the

84