that are
largest. The susceptible person who is not trained to discriminate
closely will pick out of each pair the card that has the largest
number upon it.

[Sidenote: _Testing the Confidential Man_]

This test can be made one of a series used in examining applicants
for commercial positions. It can also be used to discover the
weakness of certain employees, such as buyers, secretaries and
others who are entrusted with secrets and commissions requiring
discretion, and who must be proof against the deceptions practiced
by salesmen, promoters and others with seductive propositions.

[Sidenote: _Tests for Credulity_]

This examination can be carried still further to test the subject's
credulity or power of discrimination. What is known as the "force
card" test was originally devised by a magician, but has been
adopted in experimental psychology. Take a pack of cards and shuffle
them loosely in the two hands, making some one card, say the ace of
spades, especially prominent. The subject is told to "take a card."
The suggestive influence of the proffered card will cause nine
persons out of ten to pick out that particular card.

Turning from illusions of suggestion, shape and size, another field
of peculiar sensory illusions is found in color aberration. Some
colors look closer than others. For instance, paint an object red
and it seems nearer than it would if painted green.

[Sidenote: _What Colors Look Nearest_]

Aside from the obvious uses to which these sense-illusions can be
put, they form the basis for a number of psychological experiments
to test the abilities of persons in many ways. Here is a test which
deals with the range of attention. If you desire to discover the
capacity of any person to pay attention to unfamiliar questions or
subjects which might at some future time have great importance, try
this test. Have a piece of pasteboard cut into squares, circles,
triangles, halfmoons, stars and other forms. Then write upon each
piece some such word as hat, coat, ball or bat. The objects are
then placed under a cloth cover and the subject to be examined is
told to concentrate his attention on the shapes alone, paying no
attention to the words. The cloth is lifted for five seconds and
then replaced. The subject is then told to draw with a pencil the
different shapes and such _words_ as he may chance to remember. The
experiment should then be repeated, with the injunction to pay no
attention to the shapes but