The bicycle problem is our own invention. Binet used the other two and required both to be answered correctly. The test was located in year XII of the 1908 scale, and in year XV of the 1911 revision. Goddard and Kuhlmann retain it in the original location. The Stanford results of 1911, 1912, 1914, and 1915 agree in showing the test too difficult for year XII, even when only two out of three correct responses are required. If the original form of the experiment is used, it is exceedingly difficult for year XV. As here given it fits well at year XIV.
XIV, 5. Arithmetical reasoning
Procedure. The following problems, printed in clear type, are shown one at a time to the subject, who reads each problem aloud and (with the printed problem still before him) finds the answer without the use of pencil or paper.
- If a man’s salary is $20 a week and he spends $14 a week, how long will it take him to save $300?
- If 2 pencils cost 5 cents, how many pencils can you buy for 50 cents?
- At 15 cents a yard, how much will 7 feet of cloth cost?
Only one minute is allowed for each problem, but nothing is said about hurrying. While one problem is being solved, the others should be hidden from view. It is not permissible, if the subject gives an incorrect answer, to ask him to solve the problem again. The following exception, however, is made to this rule: If the answer given to the third problem indicates that the word yard has been read as feet, the subject is asked to read the problem through again carefully (aloud) and to tell how he solved it. No further help of any kind may be given.
Scoring. Two of the three problems must be solved correctly within the minute allotted to each. No credit is allowed for correct method if the answer is wrong.
Remarks. We have selected these problems from the list used by Bonser in his Study of the Reasoning Ability of Children in the Fourth, Fifth, and Sixth School Grades.[75]
Our tests of 279 “at age” children between 12 and 15 years reveal the surprising fact that the test as here used and scored is not passed by much over half of the children of any age in the grades below the high-school age. Of the high-school pupils 19 per cent failed to pass, 21 per cent of ordinarily successful business men (!), and 27 per cent of Knollin’s unemployed men testing up to the “average adult” level. To find average intelligence cutting such a sorry figure raises the question whether the ancient definition of man as “the rational animal” is justified by the facts. The truth is, average intelligence does not do a great deal of abstract, logical reasoning, and the little it does is done usually under the whip of necessity.
At first thought these problems will doubtless appear to the reader to be mere tests of schooling. It is true, of course, that in solving them the subject makes use of knowledge which is ordinarily obtained in school; but this knowledge (that is, knowledge of reading and of addition, subtraction, multiplication, and division) is possessed by practically all adults who are not feeble-minded, and by many who are. Success, therefore, depends upon the ability to apply this knowledge readily and accurately to the problems given—precisely the kind of ability in which a deficiency cannot be made good by school training. We can teach even morons how to read problems and how to add, subtract, multiply, and divide with a fair degree of accuracy; the trouble comes when they try to decide which of these processes the problem calls for. This may require intelligence of high or low order, according to the difficulty of the problem. As for the present test, we have shown that almost totally unschooled men of “average adult” intelligence pass this test as frequently as high-school seniors of the same mental level.