Comparison Of Weights

MATERIALS. It is necessary to have two weights, identical in shape,
size, and appearance, weighing respectively 3 and 15 grams.[50] If
manufactured weights are not at hand, it is easy to make satisfactory
substitutes by taking stiff cardboard pill-boxes, about 11/4 inches in
diameter, and filling them with cotton and shot to the desired weight.
The shot must be embedded in the center of the cotton so as to prevent

rattling. After the box has been loaded to the exact weight, the lid
should be glued on firmly. If one does not have access to laboratory
scales, it is always possible to secure the help of a druggist in the
rather delicate task of weighing the boxes accurately. A set of pill-box
weights will last through hundreds of tests, if handled carefully, but
they will not stand rough usage. The manufactured blocks are more
durable, and so more satisfactory in the long run. If the weights are
not at hand, the alternative test may be substituted.

PROCEDURE. Place the 3- and 15-gram weights on the table before the
child some two or three inches apart. Say: "_You see these blocks. They
look just alike, but one of them is heavy and one is light. Try them and
tell me which one is heavier._" If the child does not respond, repeat
the instructions, saying this time, "_Tell me which one is the
heaviest._" (Many American children have heard only the superlative form
of the adjective used in the comparison of two objects.)

Sometimes the child merely points to one of the boxes or picks up one at
random and hands it to the examiner, thinking he is asked to _guess_
which is heaviest. We then say: "_No, that is not the way. You must take
the boxes in your hands and try them, like this_" (illustrating by
lifting with one hand, first one box and then the other, a few inches
from the table). Most children of 5 years are then able to make the
comparison correctly. Very young subjects, however, or older ones who
are retarded, sometimes adopt the rather questionable method of lifting
both weights in the same hand at once. This is always an unfavorable
sign, especially if one of the blocks is placed in the hand on top of
the other block.

After the first trial, the weights are shuffled and again presented for
comparison as before, _this time with the positions reversed_. The third
trial follows with the blocks in the same position as in the first
trial. Some children have a tendency to stereotyped behavior, which in
this test shows itself by choosing always the block on a certain
side. Hence the necessity of alternating the positions. Reserve
commendation until all three trials have been given.

SCORING. The test is passed if _two of the three_ comparisons are
correct. If there is reason to suspect that the successful responses
were due to lucky guesses, the test should be entirely repeated.

REMARKS. This test is decidedly more difficult than that of comparing
lines (IV, 1). It is doubtful, however, if we can regard the difference
as one due primarily to the relative difficulty of visual discrimination
and muscular discrimination. In fact, the test with weights hardly taxes
sensory discrimination at all when used with children of 5-year
intelligence. Success depends, in the first place, on the ability to
understand the instructions; and in the second place, on the power to
hold the instructions in mind long enough to guide the process of making
the comparison. The test presupposes, in elementary form, a power which
is operative in all the higher independent processes of thought, the
power to neglect the manifold distractions of irrelevant sensations and
ideas and to drive direct toward a goal. Here the goal is furnished by
the instruction, "Try them and see which is heavier." This must be held
firmly enough in mind to control the steps necessary for making the
comparison. Ideas of piling the blocks on top of one another, throwing
them, etc., must be inhibited. Sometimes the low-grade imbecile starts
off in a very promising way, then apparently forgets the instructions
(loses sight of the goal), and begins to play with the boxes in a random
way. His mental processes are not consecutive, stable, or controlled. He
is blown about at the mercy of every gust of momentary interest.

There is very general agreement in the assignment of this test to
year V.

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Comparison Of Weights