Average Adult Alternative Test 2: Comprehension Of Physical Relations

(a) _Problem regarding the path of a cannon ball_

PROCEDURE. Draw on a piece of paper a horizontal line six or eight

inches long. Above it, an inch or two, draw a short horizontal line

about an inch long and parallel to the first. Tell the subject that the

long line represents the perfectly level ground of a field, and that the

short line represents a cannon. Explain that the cannon is "_pointed

ly (on a level) and is fired across this perfectly level

field_." After it is clear that these conditions of the problem are

comprehended, we add: "_Now, suppose that this cannon is fired off and

that the ball comes to the ground at this point here_ (pointing to the

farther end of the line which represents the field). _Take this pencil

and draw a line which will show what path the cannon ball will take from

the time it leaves the mouth of the cannon till it strikes the ground._"

SCORING. There are four types of response: (1) A straight diagonal line

is drawn from the cannon's mouth to the point where the ball strikes.

(2) A straight line is drawn from the cannon's mouth running

horizontally until almost directly over the goal, at which point the

line drops almost or quite vertically. (3) The path from the cannon's

mouth first rises considerably from the horizontal, at an angle perhaps

of between ten to forty-five degrees, and finally describes a gradual

curve downward to the goal. (4) The line begins almost on a level and

drops more rapidly toward the end of its course.

Only the last is satisfactory. Of course, nothing like a mathematically

accurate solution of the problem is expected. It is sufficient if the

response belongs to the fourth type above instead of being absurd, as

the other types described are. Any one who has ever thrown stones should

have the data for such an approximate solution. Not a day of schooling

is necessary.

(b) _Problem as to the weight of a fish in water_

PROCEDURE. Say to the subject: "_You know, of course, that water holds

up a fish that is placed in it. Well, here is a problem. Suppose we have

a bucket which is partly full of water. We place the bucket on the

scales and find that with the water in it it weighs exactly 45 pounds.

Then we put a 5-pound fish into the bucket of water. Now, what will the

whole thing weigh?_"

SCORING. Many subjects even as low as 9- or 10-year intelligence will

answer promptly, "Why, 45 pounds and 5 pounds makes 50 pounds, of

course." But this is not sufficient. We proceed to ask, with serious

demeanor: "_How can this be correct, since the water itself holds up the

fish?_" The young subject who has answered so glibly now laughs

sheepishly and apologizes for his error, saying that he answered without

thinking, etc. This response is scored failure without further


Other subjects, mostly above the 14-year level, adhere to the answer

"50 pounds," however strongly we urge the argument about the water

holding up the fish. In response to our question, "_How can that be the

case?_" it is sufficient if the subject replies that "The weight is

there just the same; the scales have to hold up the bucket and the

bucket has to hold up the water," or words to that effect. Only some

such response as this is satisfactory. If the subject keeps changing his

answer or says that he _thinks_ the weight would be 50 pounds, but is

not certain, the score is failure.

(c) _Difficulty of hitting a distant mark_

PROCEDURE. Say to the subject: "_You know, do you not, what it means

when they say a gun 'carries 100 yards'? It means that the bullet goes

that far before it drops to amount to anything._" All boys and most

girls more than a dozen years old understand this readily. If the

subject does not understand, we explain again what it means for a gun

"to carry" a given distance. When this part is clear, we proceed as

follows: "_Now, suppose a man is shooting at a mark about the size of a

quart can. His rifle carries perfectly more than 100 yards. With such a

gun is it any harder to hit the mark at 100 yards than it is at

50 yards?_" After the response is given, we ask the subject to explain.

SCORING. Simply to say that it would be easier at 50 yards is not

sufficient, nor can we pass the response which merely states that it is

"easier to aim" at 50 yards. The correct principle must be given, one

which shows the subject has appreciated the fact that a small deviation

from the "bull's-eye" at 50 yards, due to incorrect aim, becomes a

larger deviation at 100 yards. However, the subject is not required to

know that the deviation at 100 yards is exactly twice as great as at

50 yards. A certain amount of questioning is often necessary before we

can decide whether the subject has the correct principle in mind.

SCORING THE ENTIRE TEST. _Two of the three problems_ must be solved in

such a way as to satisfy the requirements above set forth.

REMARKS. These problems were devised by the writer. They yield

interesting results, when properly given, but are not without their

faults. Sometimes a very superior subject fails, while occasionally an

inferior subject unexpectedly succeeds. On the whole, however the test

correlates fairly well with mental age. At the 14-year level less than

50 per cent pass; of "average adults," from 60 to 75 per cent are

successful. Few "superior adults" fail.

The test as here given is little influenced by the formal instruction

given in the grades or the high school. In fact, 80 per cent of our

uneducated business men, as contrasted with 65 per cent of high-school

juniors and seniors, passed the test. Success probably depends in the

main upon previous interest in physical relationships and upon the

ability to understand phenomena of this kind which the subject has had

opportunity to observe.

It would be interesting to standardize a longer series of problems

designed to test a subject's comprehension of common physical

relationships. In the first few months of life a normal child learns

that objects unsupported fall to the ground. Later he learns that fire

burns; that birds fly in the air; that fish do not sink in the water;

that water does not run uphill; that it is easy to lift a leg or arm as

one lies prone in the water; that mud is thrown from a rotating wheel

(and always in the same direction); that a stone which is flying

through the air swiftly is more dangerous than one which is moving

slowly; that it is more dangerous to be run over by a train than by a

buggy; that it is hard to run against a strong wind; that cyclones blow

down trees and houses; that a rapidly moving train creates a stronger

wind than a slower train; that a feather falls through the air with less

speed than a stone; that a falling object gains momentum; that a heavy

moving object is harder to stop than a light object moving at the same

rate; that freezing water bursts pipes; that sounds sometimes give

echoes; that rainbows cannot be approached; that a lamp seems dim by

daylight; that by day the stars are not visible and the moon only barely

visible; that the headlights of an approaching automobile or train are

blinding; that if the room in which we are reading is badly lighted we

must hold the book nearer to the eyes; that running makes the heart beat

faster and increases the rate of breathing; that if we are cold we can

get warm by running; that whirling rapidly makes us dizzy; that heat or

exercise will cause perspiration, etc.

Although the causes of some of these phenomena are not understood even

by intelligent adults without some instruction, the facts themselves are

learned by the normal individual from his own experience. The higher the

mental level and the greater the curiosity, the more observant one is

about such matters and the more one learns. Many items of knowledge such

as we have mentioned could and should be standardized for various mental

levels. In devising tests of this kind we should, of course, have to

look out for the influences of formal instruction.