traits, and then theoretically to determine for which
economic tasks the presence of these qualities would
be useful and for which tasks their absence or their
deficiency would be fatal. Common sense may be
sufficient to lead us a few steps in that direction.
For instance, if we find by psychological examination
that an individual is color-blind for red and green
sensations, we may at once conclude, without any real
psychological analysis of the vocations, that he would
be unfit for the railroad service or the naval service,
in which red and green signals are of importance.
We may also decide at once that such a boy would be
useless for all artistic work in which the nuances
of colors are of consequence, or as a laborer in certain
departments of a dyeing establishment, and that such
a color-blind girl would not do at a dressmaker’s
or in a millinery store. But if we come to the
question whether such a color-blind individual may
enter into the business of gardening, in spite of
the inability to distinguish the strawberries in the
bed or the red flowers among the green leaves, the
first necessity, after all, would be to find out how
far the particular demands of this vocation make the
ability to discriminate color a prerequisite, and
how far psychical substitutions such as a recognition
of the forms and of differences in the light intensity,
may be sufficient for the practical task. Moreover,
where not merely such mental defects, but more subtly
shaded variations within normal limits are involved,
it would be superficial, if only the mental states
were examined and not at the same time the mental requirements
of the vocations themselves. The vocation should
rather remain the starting-point. We must at
first find out what demands on the mental system are
made by it and we must grade these demands in order
to recognize the more or less important ones, and,
especially for the important ones, we must then seek
exact standards with experimental methods.
Such an experimental investigation may proceed according
to either of two different principles. One way
is to take the mental process which is demanded by
the industrial work as an undivided whole. In
this case we have to construct experimental conditions
under which this total activity can be performed in
a gradual, measurable way. The psychical part
of the vocational work thus becomes schematized, and
is simply rendered experimentally on a reduced scale.
The other way is to resolve the mental process into
its components and to test every single elementary
function in its isolated form. In this latter
case the examination has the advantage of having at
its disposal all the familiar methods of experimental
psychology, while in the first case for every special
vocational situation perfectly new experimental tests
must be devised.