Comparison Of Lines

PROCEDURE. Present the appropriate accompanying card with the lines in

horizontal position. Point to the lines and say: "_See these lines. Look

closely and tell me which one is longer. Put your finger on the longest

one._" We use the superlative as well as the comparative form of _long_

because it is often more familiar to young subjects. If the child does

not respond, say: "_Show me which line is the biggest._" Then withdraw

the card, turn it about a few times, and present it again with the

position of the two lines reversed, saying: "_Now show me the longest._"

Turn the card again and make a third presentation.

SCORING. All three comparisons must be made correctly; or if only two

responses out of three are correct, all three pairs are again shown,

just as before, and if there is no error this time, the test is passed.

The standard, therefore, is _three correct responses out of three, or

five out of six_.

Sometimes the child points, but at no particular part of the card. In

such cases it may be difficult to decide whether he has failed to

comprehend and to make the discrimination or has only been careless in

pointing. It is then necessary to repeat the experiment until the

evidence is clear.

REMARKS. As noted by Binet, success in this test depends on the

comprehension of the verbal directions rather than on actual

discrimination of length. The child who would unerringly choose the

larger of two pieces of candy might fail on the comparison of lines.

However, since the child must correctly compare the lines three times in

succession, or at least in five out of six trials, _willingness to

attend_ also plays a part. The attention of the low-grade imbecile, or

even of the normal child of 3 years, is not very obedient to the

suggestions of the experimenter. It may be gained momentarily, but it is

not easily held to the same task for more than a few seconds. Hence some

children who perfectly comprehend this task fail to make a succession of

correct comparisons because they are unable or unwilling to bring to

bear even the small amount of attention which is necessary. This does

not in the least condone the failure, for it is exactly in such

voluntary control of mental processes that we find one of the most

characteristic differences between bright and dull, or mature and

immature subjects.

There has been little disagreement as to the proper location of this