SENSORY ILLUSIONS AND SUGGESTIONS FOR THEIR USE
[Sidenote: _Unreliability of Sense-Organs_]
Figure 1 shows two lines of equal length, yet the vertical line will
to most persons seem longer than the horizontal one.
[Illustration: FIG. 1.]
In Figure 2 the lines A and B are of the same length, yet the lower
seems much longer.
[Illustration: FIG. 2.]
Those things look smallest over which the eye moves with least
resistance.
In Figure 3, the distance from A to B looks longer than the distance
from B to C because of the time we involuntarily take to notice each
dot, yet the distances are equal.
[Illustration: FIG. 3.]
[Sidenote: _Being and Seeming_]
For the same reason, the hatchet line (A-B) appears longer than
the unbroken line (C-D) in Figure 4, and the lines E and F appear
longer than the space (G) between them, although all are of equal
length.
[Illustration: FIG. 4.]
Filled spaces look larger than empty ones because the eye
unconsciously stops to look over the different parts of the filled
area, and we base our estimate upon the extent of the eye movements
necessary to take in the whole field. Thus the filled square in
Figure 5 looks larger than the empty one, though they are of equal
size.
[Illustration: FIG. 5.]
White objects appear much larger than black ones. A white square
looks larger than a black one. It is said that cattle buyers who
are sometimes compelled to guess at the weight of animals have
learned to discount their estimate on white animals and increase
it on black ones to make allowances for the optical illusion.
[Illustration: THIS MAN AND THIS BOY ARE OF EQUAL HEIGHT, BUT
ASSOCIATION OF IDEAS MAKES THE MAN LOOK MUCH THE LARGER]
[Sidenote: _Use of Illusions in Business_]
The dressmaker and tailor are careful not to array stout persons
in checks and plaids, but try to convey an impression of sylph-like
slenderness through the use of vertical lines. On the other hand,
you have doubtless noticed in recent years the checkerboard and
plaid-covered boxes used by certain manufacturers of food products
and others to make their packages look larger than they really are.
The advertiser who understands sensory illusions gives an impression
of bigness to the picture of an article by the artful use of lines
and contrasting figures. If his advertisement shows a picture of a
building to which he wishes to give the impression of bigness, he
adds contrasting figures such as those of tiny men and women so that
the unknown may be measured by the known. If he shows a picture of a
cigar, he places the cigar vertically, because he knows that it will
look longer that way than if placed horizontally.
[Sidenote: _Making an Article Look Big_]
A subtle method of conveying an idea of bigness is by placing
numbers on odd-shaped cards or blocks, or on any blank white space.
The object or space containing the figures always appears larger
than the corresponding space without the figures.
This fact has been made the basis of a psychological experiment to
determine the extent to which a subject's judgment is influenced by
suggestion. To perform this experiment cut bits of pasteboard into
pairs of squares, circles, stars and octagons and write numbers
of two figures each, say 25, 50, 34, 87, etc., upon the different
pieces. Tell the subject to be tested to pick out the forms 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 to remember as many words as possible,
and write them down on such _forms_ as he may happen to recall.
[Sidenote: _Testing the Range of Attention_]
Of course, the real object is to determine whether the subject will
see more than he is told, or whether he is a mere automaton. The
result will tell whether his attention is of the narrow or broad
type. If it be narrow, he will see only the forms in the first case
and no words, and in the second case he will remember the words but
be unable to recall the shape of the pieces of cardboard.
[Sidenote: _A Guide to Occupational Selection_]
His breadth of attention will be shown by the number of correct
forms and words combined which he is able to remember in both cases.
In other words, this will measure his ability to pay attention to
more than one thing at a time.
Other things being equal, the narrow type of attention belongs to
a man fitted for work as a bookkeeper or mechanic, while the broad
type of attention fits one for work as a foreman or superintendent
or, lacking executive ability, for work requiring the supervision
of mechanical operations widely separated in space.
[Sidenote: _Test for Attention to Details_]
The ordinary man sees but one thing at a time, while the exceptional
man sees many things at every glance and is prepared to remember and
act upon them in emergency.
Having determined a person's scope of attention, you may want
to test his accuracy in details as compared with other men. To
conduct such an experiment dictate a statement which will form one
typewritten letterhead sheet. This statement should comprise facts
and figures about your business of which the subjects to be tested
are supposed to have accurate knowledge. After this original page is
written, have your typist write out another set of sheets in which
there are a large number of errors both in spelling and figures.
Then have each of the persons to be examined go through one of these
sheets and cross out all the wrong letters or figures. Time this
operation. The man who does it in the quickest time and overlooks
the fewest errors, naturally ranks highest in speed and accuracy
of work.
[Sidenote: _Other Business Applications_]
Look into your own business and you will undoubtedly find some
department, whether it be store decoration, office furnishing,
window dressing, advertising, landscape work or architecture, in
which a systematic application of a knowledge of sensory illusions
will produce good results.