PILLSBURY: _Essentials of Psychology_, Chapters VI and IX.

PYLE: _The Outlines of Educational Psychology_, Chapter XV.

t.i.tCHENER: _A Beginner's Psychology_, Chapters V, VI, and X.

CHAPTER IX

INDIVIDUAL DIFFERENCES

=Physical Differences.= One never sees two people whose bodies are exactly alike. They differ in height or weight or color of the skin. They differ in the color of the hair or eyes, in the shape of the head, or in such details as size and shape of the ear, size and shape of the nose, chin, mouth, teeth, feet, hands, fingers, toes, nails, etc. The anatomist tells us that we differ internally just as we do externally. While the internal structure of one person has the same general plan as that of another, there being the same number of bones, muscles, organs, etc., there are always differences in detail. We are built on the same plan, _i.e._ we are made after a common type. We vary, above and below this type or central tendency.

Weight may be taken for ill.u.s.tration. If we should weigh the first thousand men we meet, we should find light men, heavy men, and men of medium weight. There would be few light men, few heavy men, but many men of medium weight. This fact is well shown in diagram by what is known as a curve of distribution or frequency surface, which is constructed as follows: Draw a base line A B, and on this line mark off equal distances to represent the various weights. At the left end put the number representing the lightest men and at the right the number representing the heaviest men; the other weights come in between in order. Then select a scale; we will say a millimeter in height above the base line represents one person of the weight represented on the base, and in drawing the upper part of the figure, A C B, we have but to measure up one millimeter for each person weighed, of the weight indicated below on the base.

[Ill.u.s.tration: FIGURE V--FREQUENCY SURFACE--WEIGHT The solid line represents men, the broken line, women.]

A study of this frequency surface shows a tendency for people to be grouped about the central tendency or average. There are many people of average weight or nearly so, but few people who deviate widely from the average weight. If we measure people with reference to any other physical characteristic, or any mental characteristic, we get a similar result, we find them grouped about an average or central tendency.

=Mental Differences.= Just as we differ physically, so also we differ mentally, and in the various aspects of our behavior. The accompanying diagram (Free a.s.sociation) shows the distribution of a large number of men and women with respect to the speed of their flow of ideas. When men and women are measured with respect to any mental function, a similar distribution is found.

[Ill.u.s.tration: FIGURE VI--FREQUENCY SURFACE--FREE a.s.sOCIATION Solid line, men; broken line, women. The numbers below the base represent the number of words written in the Free a.s.sociation test, and the numbers at the left represent the number of people making the respective scores.]

An interesting question is whether our mental differences have any relation or connection with one another. If one mental characteristic is of high order, are all the others of high order also? Does a good memory indicate a high order of attention, of a.s.sociation, of imagination, of learning capacity? Experiments show that mental characteristics have at least some degree of independence. But the rule is that they generally go together, a high order of ability in one mental function indicating a high order of ability in at least some others, and a low order of ability in one function indicating a low order in other functions.

However, it seems that abilities that are very much specialized, such as musical ability, artistic ability, etc., may exist in high order while other mental functions may be only mediocre. It is a common thing for a musical person to be of rather poor ability otherwise. To the extent that special abilities require specialized differences in the structure of brain, nervous system, or sense organ, they can exist in some degree of independence of other functions. Musical ability to some extent does require some such differences and may therefore be found either with a high or a low degree of ability in other characteristics.

It is doubtless true that at maturity the unequal power of mental functions in the same person may be partly due to the fact that one function has been exercised and others neglected. A person having very strong musical tendencies is likely to have such a great interest in music that he will think other activities are not worth while, and will consequently neglect these other activities. It will therefore turn out that at maturity the great differences in mental functions in such a person are in part due to exercise of one function and neglect of others. But there can be no doubt that in many cases there are large original, inherited differences, the individual being poor in one aspect of mind and good in others. Feeble-minded people are usually poor in all important aspects of mind. However, one sometimes finds a feeble-minded person having musical or artistic ability, and often such a person has a good rote memory, sometimes a good verbal memory. However, the so-called higher mental functions--logical memory, controlled a.s.sociation, and constructive imagination--are all poor in a feeble-minded person.

Each mental function may be looked upon as in some measure independent; each is found existing in people in varying degrees from zero ability up to what might be called genius ability. The frequency curves in Fig. VI show this. Take rote memory for example. Idiots are found with practically zero ability in rote memory. At the other extreme, we find mathematical prodigies who, after watching a long freight train pa.s.s and noting the numbers of the cars, can repeat correctly the number of each car. Rote memory abilities can be found representing every step between these two extremes. This principle of distribution holds true in the case of all mental functions. We find persons practically without them, and others possessing them in the highest order, but most people are grouped about the average ability.

=Detecting Mental Differences.= It has already been said that mind has many different aspects and that people differ with respect to these aspects. Now let us ask how we can measure the degree of development of these aspects or functions of mind. We measure them just as we measured muscular speed as described in the first chapter. Each mental function means ability to do something--to learn, to remember, to form images, to reason, etc. To measure these different capacities or functions we have but to require that the person under consideration _do_ something, as learn, remember, etc., and measure how well and how fast he does it, just as we would measure how far he can jump, how fast he can run, etc.

In such measurements, the question of practice is always involved. If we measure running ability, we find that some are in practice while others are not. Those in practice can run at very nearly their ultimate capacity. Those who are not in practice can be trained to run much faster than they do. To get a true measure of running capacity, we should practice the persons to be measured till each runs up to the limit of his capacity, and then measure each one's speed. The same thing is true, to some extent, when we come to measure mental functions proper. However, the life that children live gives exercise to all fundamental functions of the mind, and unless some of the children tested have had experience which would tend to develop some mental functions in a special way, tests of the various aspects of learning capacity, memory, a.s.sociation, imagination, etc., are a fairly good measure of original, inherited tendencies.

Of course, it must be admitted that there are measurable differences in the influence of environment on children, and when these differences are extreme, no doubt the influence is shown in the development of the child's mind. A child reared in a home where all the influences favor its mental development, ought to show a measurable difference in such development when compared with a child reared in a home where all the influences are unfavorable. It is difficult to know to what extent this is true, for the hereditary and environmental influences are usually in harmony, the child of good hereditary stock having good environmental influences, and vice versa. When this is not the case, _i.e._ when a child of good stock is reared under poor environmental influences, or when a child of poor stock is reared under good influences, the results seem to show that the differences in environment have little effect on mental development, as far as the fundamental functions are concerned, except in the most extreme cases.

Each mental function is capable of some development. It can be brought up to the limit of its possibilities. But recent experiments indicate that such development is not very great in the case of the elementary, fundamental functions. Training, however, has a much greater effect on complex mental activities that involve several functions. Rote memory is rather simple; it cannot be much affected by training. The memory for ideas is more complex; it can be considerably affected by training. The original and fundamental functions of the mind depend upon the nature of the nervous system which is bequeathed to us by heredity. This cannot be much changed. However, training has considerable effect on the coordinations and combinations of mental functions. Therefore, the more complex the mental activities which we are testing, the more likely they are to have been affected by differences in experience and training.

If we should designate the logical memory capacity of one person by 10, and that of another by 15, by practice we might bring the first up to 15 and the second to 22, but we could not equalize them. We could never make the memory of the one equal to that of the other. In an extreme case, we might find one child whose experience had been such that his logical memory was working up to the limit of its capacity, while the other had had little practice in logical memory and was therefore far below his real capacity. In such a case, a test would not show the native difference, it would show only the present difference in functioning capacity.

Fairly adequate tests for the most important mental functions have been worked out. A series of group tests with directions and norms follow.

The members of the cla.s.s can use these tests in studying the individual differences in other people. The teacher will find other tests in the author's _Examination of School Children_, and in Whipple's _Manual of Mental and Physical Tests_.

=MENTAL TESTS=

GENERAL DIRECTIONS

The results of the mental tests in the school will be worse than useless unless the tests are given with the greatest care and scientific precision. Every test should be most carefully explained to the children so that they will know _exactly_ what they are to do. The matter must be so presented to them that they will put forth _all possible_ effort.

They must take the tests seriously. Great care must be taken to see that there is no cheating. The work of each child should be his own work. In those tests in which time is an important element, the time must be _carefully kept_, with a stop watch if one is available. The papers should be distributed for the tests and turned face downward on the pupil's desk. The pupil, when all are ready to begin, should take the paper in his hand and at the signal "begin" turn it over and begin work, and when the signal "stop" is given, should quit work instantly and turn the paper over. Before the work begins, the necessary information should be placed on each paper. This information should be the pupil's name, age, grade, s.e.x, and school. This should be on every paper. When the test is over the papers should be immediately collected.

LOGICAL MEMORY

=Object.= The purpose of this test is to determine the pupil's facility in remembering and reproducing ideas. A pupil's standing in the test may serve as an indication of his ability to remember the subject matter of the school studies.

[Ill.u.s.tration: FIGURE VII--LOGICAL MEMORY "WILLIE JONES"]

=Method.= The procedure in this test is for the teacher to read slowly and distinctly the story to be reproduced. Immediately after the reading the pupils are to write down all of the story that they can recall. They must not begin to write till _after_ the reading. Ten minutes should be allowed for the reproduction. This is ample time, and each pupil should be told to use the whole time in working on his reproduction. At the end of ten minutes, collect the papers. Care should be taken to see that each pupil does his own work, that there is no copying. Before reading the story, the teacher should give the following instructions:

I shall read to you a story ent.i.tled "Willie Jones and His Dog" (or "A Farmer's Son," or "A Costly Temper," as the case may be). After I have read the story you are to write down all you can remember of it. You are not to use the exact words that I read unless you wish.

You are to use your own words. Try to recall as much as possible and write all you recall. Try to get all the details, not merely the main facts.

=Material.= For grades three, four, and five, use "Willie Jones and His Dog"; for grades six, seven, and eight, use "A Farmer's Son"; for the high school, use "A Costly Temper." The norms for the latter are based on eighth grade and high school pupils.

WILLIE JONES AND HIS DOG

Willie

Jones

was a little

boy

only

five years old.

He had a dog

whose name was Buster.

Buster was a large

dog

with long,

black,

curly

hair.

His fore

feet

and the tip

of his tail

were white.

One day

Willie's mother

sent him

to the store

which was only

a short

distance away.

Buster went with him,

following behind.

As Buster was turning

at the corner,

a car

struck him

and broke

one

hind

leg

and hurt

one

eye.

Willie was

very

sorry

and cried

a long

time.

Willie's father

came

and carried

the poor

dog

home.

The broken leg

got well

in five

weeks

but the eye

that was hurt

became blind.

A FARMER'S SON

Will

was a farmer's

son

who attended school

in town.

His clothes

were poor and his boots

often smelled

of the farmyard

although he took great

care of them.

Since Will had not gone to school

as much

as his cla.s.smates,

he was often

at a disadvantage,

although his mind

was as good

as theirs,--

in fact, he was brighter

than most

of them.

James,

the wit

of the cla.s.s,

never lost an opportunity

to ridicule

Will's mistakes,

his bright

red

hair,

and his patched

clothes.

Will

took the ridicule

in good part

and never

lost his temper.

One Sat.u.r.day

as Will

was driving

his cows

to pasture,

he met James

teasing

a young

child,

a cripple.

Will's

indignation

was aroused

by the sight.

He asked

the bully

to stop,

but when he would not,

Will pounced

upon him

and gave him

a good

beating,

and he would not

let James go

until he promised

not to tease

the crippled

child

again.

A COSTLY TEMPER

A man

named John

Murdock

had a servant

who worried him

much by his stupidity.

One day

when this servant was more

stupid

than usual,

the angry

master

of the house

threw a book

at his head.

The servant

ducked

and the book flew

out of the window.

"Now go

and pick that book up!"

ordered the master.

The servant

started

to obey,

but a pa.s.serby

had saved him

the trouble,

and had walked off

with the book.

The scientist

thereupon

began to wonder

what book

he had thrown away,

and to his horror,

discovered

that it was a quaint

and rare

little

volume

of poems,

which he had purchased

in London

for fifty

dollars.

But his troubles

were not over.

The weeks went by

and the man had almost

forgotten his loss,

when, strolling

into a secondhand

bookshop,

he saw,

to his great delight,

a copy of the book

he had lost.

He asked the price.

"Well,"

said the dealer,

reflectively,

"I guess we can let you have it

for forty

dollars.

It is a very

rare book,

and I am sure

that I could get seventy-five

dollars for it

by holding on a while."

The man of science

pulled out his purse

and produced the money,

delighted at the opportunity of replacing

his lost

treasure.

When he reached home,

a card

dropped out

of the leaves.

The card was his own,

and further

examination

showed that he had bought back

his own property.

"Forty dollars'

worth of temper,"

exclaimed the man.

"I think I shall mend my ways."

His disposition

afterward

became so

good

that

the servant became worried,

thinking the man

must be ill.

[Ill.u.s.tration: FIGURE VIII--LOGICAL MEMORY--"A FARMER'S SON"]