became convinced that all the working-chairs
for the women were too low and that the laborers therefore had to hold
their arms in a psychophysically unfavorable position during the
handling of the apparatus. All were strongly opposed to the
introduction of higher chairs. The result was that the manager
arranged for the chairs to be raised a few millimeters every evening,
without the knowledge of the working-women, as soon as the factory was
empty. After a few weeks the chairs had reached the right height
without those engaged in the work having noticed it at all. The
outcome was a decided increase of efficiency.

But the most rational scheme will after all be to prepare for such
arrangements of tools and apparatus by systematic experiments in the
psychological laboratory. The subtlety of such investigations will
lead far beyond the point which is accessible to the attempts of
scientific management. Exact experiments on attention, for instance,
will have to determine how the various parts of the apparatus are to
be distributed best in space if the laborer must keep watch for
disturbances at various places. Only the laboratory experiment can
find the most favorable speed of the machine or can select the muscles
to which the mind can send the most effective impulses. The
construction of the machine must then be adapted to such results. In
the Harvard laboratory, for instance, a practical question led us to
examine which fingers would allow the quickest alternation of key
movements.[29] If any two of the ten fingers perform for ten seconds
the quickest possible alternation of motion, as in a trill, the
experiment can demonstrate exactly the differences between the various
combinations of fingers and the individual fluctuations for these
differences. With an electrical registration of the movements of the
alternating fingers we studied in hundredths of a second the time for
the motions of two hands and of fingers of the same hand, in order to
adjust the keys of a certain machine to the most favorable impulses.

We approach this group of problems from another side when we test the
relations of various kinds of machines to various mental types.
Psychologists have studied, for example, the various styles of
typewriting machines.[30] From a purely commercial point of view the
merits of one or another machine are praised as if they were
advantageous for every possible human being. The fact is that such
advantages for one may be