A final
maximum rapidity must be secured from the start by the choice of those
motions which have been standardized by careful experiments.
It is also psychophysically important to demand that the movements
shall not be suddenly stopped, if that can be avoided. Any
interruption of a movement presupposes a special effort of the will
which absorbs energy, and after the interruption a new start must be
made of which the same is true. On the other hand, if chains of
movements become habitual, the psychophysical effort will be reduced
to the minimum, inasmuch as each movement finds its natural end and is
not artificially interrupted by will, and at the same time each
movement itself becomes a stimulus for the next movement by its
accompanying sensations. The traditional method, for instance, demands
that a brick be lifted with one hand and a trowel with mortar by the
other hand. After that the lifting movement is interrupted, the brick
comes to rest in the hand of the mason until the mortar has been
spread on and the place prepared for the new brick. Then only begins a
new action with the brick. This method was fundamentally changed. The
laborers learned to swing the brick with one hand from the pack to
the wall and at the same time to distribute the mortar over the next
brick with the other hand. This whole complex movement is of course
more difficult and demands a somewhat longer period of learning, but
as soon as it is learned an extreme saving of psychophysical energy
and a correspondingly great economic gain is secured.
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