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abilities, noticed in Chapter III, due to native equipment or to
opportunity and environment? To what extent does a person
make of himself what he does by virtue of his opportunities or by
virtue of his inherent make-up? What part of the future adult
individual is really determined by the school as an agency of
his environment and what part is beyond the control of the
school?

Methods of Studying Heredity. Any individual is the resultant
of the interplay between his inherited equipment and the stimuli
from his environment. Hence, theoretically, there are two general
methods of studying the problem: First, by keeping the environ-
ment constant and varying the ancestry, so to speak; or second,
by keeping the ancestry constant and varying the environment.
That is, according to the former plan we would place children of
entirely different ancestry into the same environment from birth

73



74 EDUCATIONAL PSYCHOLOGY

up to a given point in life, and then measure the amount of simi-
larity or difference; or according to the latter plan, we would place
children of the same ancestry into entirely different environments
from birth to a given point in life, and then measure the amount
of similarity or difference. Such ideally scientific conditions are
practically impossible to obtain. The best we can do is to measure
the resemblances or differences of children of the same ancestry
and compare them \\ith the resemblances or differences of children
of different ancestry, both groups living in approximately the
same environment.

General Views Concerning Mental Heredity. Two extreme
views concerning heredity are possible according to our conception
of the relative roles played by heredity and en\aronment in the
production of adult individuals. We may assume on the one hand
that what a person becomes is absolutely and entirely determined
by heredity, and that environment makes no difference whatever;
or we may assume on the other hand that what a person becomes is
completely and entirely determined by his environment, and that
heredity plays no part. Neither view has been held by any serious
student of heredity in recent times. Views very closely approach-
ing these extremes, have, however, been held by prominent writers
and thinkers in times past; whereas various views between these
extremes are generally being held at the present time, depending
upon the conception as to whether the larger, smaller, or equal
share is contributed by heredity or by environment. The view
held by most scientific students of the problem to-day gives
weight to both elements with perhaps the major emphasis upon
heredity.

The Similarity of Abilities among Related Eminent Persons.
This particular method of attacking the problem was historically
the first means of approaching the study of the inheritance of
mental traits. Two extensive investigations on this aspect of the
subject have been made. The first was carried out by Sir Francis
Galton and published in 1869. Galton made a study of 977 emi-
nent men, each of whom was the most eminent among 4,000 persons.
He proceeded to determine how many relatives of equal eminence
and of varying degrees of relationship each person possessed.
In this manner he found that these 977 men had the following
relatives of a like degree of eminence: 89 fathers, 114 brothers, 129
sons, 52 grandfathers, 37 grandsons, 53 uncles, and 61 nephews, or
a total of 535. Galton further pointed out that 977 ordinary men



THE INHERITANCE OF MENTAL TRAITS 75

selected by chance from the population at large would have only
four such eminent relatives. He concluded as follows:

"i. That men who are gifted with high abilities — even men of class
E — 'easily rise through all the obstacles caused by inferiority of social
rank.

"2. Countries where there are fewer hindrances than in England, to a
poor man rising in hfe, produce a much larger proportion of persons of
culture, but not of what I call eminent men. (England and America are
taken as illustration.)

"3. ]\Ien who are largely aided by social advantages are unable to
achieve eminence, unless they are endowed with high natural gifts."

More recently an extensive study was made by Woods ('06)
on mental and moral heredity in royalty. Woods made a com-
parison of 671 members of royal families in Europe by giving each
person a rating on a scale of i to 10 in which 10 signified excep-
tionally high ability or genius, and i represented exceedingly low
ability or imbecility. These ratings were made by the judgment
of Woods himself according to the reports of these persons in
histories and biographies. On the basis of these estimates, a
tabulation was then made of the relationship of persons of various
degrees of ability. He found that most of the eminent persons
were grouped about four stocks or families out of fifteen, namely,
the families of Frederick the Great, Queen Isabella of Spain,
William the Silent, and Gustavus Adolphus. Likewise, he found
that most of the persons of lowest ability were grouped around
certain families in Spain and Russia, and the persons of mediocre
ratings, four to seven, centered about some half dozen royal families
including the houses of Hanover, Saxe-Coburg-Gotha, Reuss,
Mecklenburg, Hapsburg in Austria, Holstein, Denmark, Saxony,
Savoy, Orleans and modern Portugal. The ratings, of course,
were not absolutely correct measurements of their abilities, but
they, no doubt, represented greater validity than general impres-
sions would. He further computed coeflScients of resemblance in
intellect and morals as follows:

I. In intellect:

Offspring and father 30

" " grandfather 16

" " great-grandfather 15

II. In morals:

Offspring and father 30

" " grandfather 175







76 educyVtional psychology

Dr. Woods then attempted to determine whether or not thefact of
accession to the throne by virtue of birth gave an individual greater
opportunity for eminence. This he states in the following manner:

"There is one peculiar way in which a little more than half of all
males have had a considerable advantage over the others in gaining
distinction as important historical characters. The eldest sons, or if not
the eldest, those sons to whom the succession has devolved, have un-
doubtedly had greater opportunities to become illustrious than those to
whom the succession did not fall by right to primogeniture. I think
every one must feel that perhaps much of the greatness of Frederick II
of Prussia, Gustavus Adolphus, and William the Silent, was due to their
official positions; but an actual mathematical count is entirely opposed to
this view. The inheritors of the succession are no more plentiful in the
higher grades than in the lower. The figures show the number in each
grade who came into power by inheriting the throne."

Grades i 23456789 lo

Total No. in each sradc 7 21 41 49 71 70 68 43 18 7

Succession 'nhcritors 5 14 26 31 49 38 45 23 12 4

Per cent 71 67 63 64 69 54 67 54 67 57

"It is thus seen that from 54 to 71% inherited the succession in the
different grades. The upper grades are in no way composed of men
whose opportunities were enhanced by virtue of this high position. Thus
we see that a certain very decided difference in outward circumstances —
namely, the right of succession — can be proved to have no effect on
intellectual distinction, or at least so small as to be unmeasurable without
much greater data. The younger sons have made neither a poorer nor a
better showing. ('06, pp. 2S5-286.)"

"The upshot of it all is, that as regards intellectual life, environment is
a totally inadequate explanation. If it explains certain characters in
certain instances, it always fails to explain as many more; while heredity
not only explains all (or at least 90%) of the intellectual side of character
in practically every instance, but does so best when questions of en-
vironment are left out of the discussion. Therefore, it would seem that
we are forced to the conclusion that all these rough differences in in-
tellectual activity which are susceptible of grading on a scale of ten are
due to predetermined differences in the primary germ-cells:" ('06, p. 286:^^

Wliile heredity no doubt plays an important part in the produc-
tion of intellect and character the part attributed to it by Woods
that it explains " at least 90% of the intellectual side of character
in every case " is hardly warranted either by the findings of other
investigators or by the results of Woods himself. His corrrelation
between father and offspring is only .30.



THE INHERITANCE OF MENTAL TRAITS 77

Similarities of Abilities Among Related Defective and Low
Grade Persons. Quite a number of studies have been made in
recent years concerning the frequency with which defective persons
are either distantly or closely related. One of the first studies
was that of the Jukes reported by R. G. Dugdale in 1S77. Max
Juke, born in 1720, was a shiftless truant, who married an equally
worthless woman. Up to 1877 there had been five generations with
approximately 1,200 descendants among whom have been traced
the following types of persons: 310 paupers, 7 murderers, 60 habit-
ual thieves, 50 prostitutes, 130 convicted of crime, 300 died in
infancy, 440 physical wrecks from debauchery, only 20 learned a
trade, and 10 of these learned it in prison. The estimated cost to
the State of New York has been put at approximately $1,000 a
person. In contrast with this lineage, a comparison has been
suggested with the Jonathan Edwards family, which had ai)proxi-
mately 1,400 descendants in the same period of time. Among
them there have been 120 graduates of Yale alone, 14 college
presidents, over 100 professors, 135 books of merit have been
written by various members of the family, and 118 journals have
been edited by them. Aaron Burr was the only black sheep among
them and he can certainly not be classed as an intellectually de-
fective person. (Winship '00).

Poellman of Bonn (Guyer '16, p. 271) made a study of a family
called the Zeros in which 800 descendants were traced through six
generations back to a female drunkard. Among them were found
102 professional beggars, 107 illegitimate offspring, 181 prostitutes,
54 inmates of almshouses, 76 convicted of crime, and 7 murderers.
The cost to the state was placed at $1,206,000.

More recently a very interesting study was conducted by Dr.
Goddard of the Training School at Vineland, New Jersey. Dr.
Goddard ('12) traced the ancestry of a young girl who had been
brought to his institution. It was found that the lineage went
back to a man, Martin Kallikak, a soldier in the Revolutionary
War, who was the progenitor of two lines of descendants. (See
Figure 31.) He had an illegitimate son whose mother was feeble-
minded. This was the establishment of line — A — which had, down
to the time of the study, 480 direct descendants among whom
were found the following: 143 feeble-minded, 292 unknown, 36
illegitimates, 33 prostitutes, 24 alcohohcs, 3 epileptics, 82 died in
infancy, 3 criminals, 8 keepers of disreputable houses, and only 46
normal individuals. Apparently human nature does not gather



^73



EDUCATIONAL PSYCHOLOGY



grapes of thorns or figs of thistles. After his return from the war,
Martin married a woman of normal intelligence and from this
Uneage — B — there had come during the same period of time, 4q6
direct descendants, of whom all were normal individuals with the



THE
LAWFUL WfFE



®-



MARTIN KALLIKAK SR.

THE NAMELESS
FEEBLE-MINDED GIRL

NOT MSRRIED rf^



[S (N) (N) (N) (N) [N] ^







RHODA ZABETH



H i i ® °-"- d (N) ® ©




ILLEGITIMATE
DEBORAH

BORN IN
ALMSHOUSE



Fig. 31. — Descendants of the Kallikak Family. Squares = males, circles =
females, black squares or circles = feebleminded, open squares or circles =
normal persons. The lineage was traced back from Deborah. After Goddard.

exception of five, one of whom was reported as mentally defective,
two as alcoholics, one as sexually immoral, and one as a case of
religious mania. There were no epileptics or criminals, and only
15 died in infancy. The remainder were good citizens, including
doctors, lawyers, educators, judges, and business men.

One thing seems to stand out very conspicuously from the



J



THE INHERITANCE OF MENTAL TRAITS 79

numerous facts of family histories that have been unravelled in
recent years, namely, that much defective mentality, degeneracy,
and crime is a matter of ancestry. General opinion among persons
in charge of institutions for defectives is that two-thirds of all
cases are due to heredity and one-third to environmental or un-
known causes. Thus Dr. Alfred Wilmarth, Superintendent of the
Wisconsin Home for Feeble-minded, says:

" My own observations, and those of others in this country and Europe,
would indicate that at least two-thirds of the feeble-minded have defec-
tive relatives. This is significant. Mental accident may occur in any
family, but it is rarely a second case occurs unless there is a tendency to
nerve degeneracy. (Quoted by Guyer,'i6, p. 245.)

"I present to you the results of compiling the histories on 1,000 appli-
cations, where our information is most thorough; but I am confident
that these do not tell the whole story. In 311 of these any neurotic taint
in the family history is absolutely denied. In 365 cases at least one near
relative suffers from one of the graver forms of nervous or mental trouble;
in 170, two relatives were found; in 73 cases, three relatives, and in 81
cases four or more. These figures agree very accurately with the results
of other observers in this country and abroad. It is safe to say that less
than one-third of the defective classes are the results of disease or trau-
matism in families capable of transmitting a healthy, well developed
nervous system."

Dr. Goddard of the Training School, Vineland, New Jersey,
states in connection with his tests of 2,000 children:

"But we now know that 65% of these children have inherited the
condition, and that if they grow up and marry they will transmit the
same condition to their offspring. Indeed, we know that this class of
people is increasing at an enormous rate in every community and unless
we do something to stop this great stream of bad protoplasm we shall
some day be swamped in a sea of degeneracy."

Likewise Dr. A. C. Rogers of the Minnesota School for Feeble-
minded, at Faribault, says:

"We have no survey of mentality in this country except in very small
areas, but probably about 65% of the feeble-minded children that we
know of are feeble-minded from heredity; that is, they come from families
in which there is much feeblc-mindcdness, usually associated with various
neuroses or psychoses. There are about 35% approximately that are
acquired cases. These cases develop from various things. Full develop-
ment may be prevented during gestation, or early childhood, or early
adolescence, but these acquired cases are entirely distinct from the
hereditary ones." (Guyer '16, p. 246.)



8o EDUCATIONAL PSYCHOLOGY

Likewise, Dr. Martin W. Barr of the Pennsylvania Training
School for Feeble-minded Children states:

"In my individual study of 4,050 cases of imbecility, I find 2,631 or
65.34%, caused by malign heredities; and of these 1,030, or 25.43%, are
due to direct inheritance of idiocy; and 280, or 6.91%, to insanity."

To one who wishes to argue in favor of environment as the chief
determining element in abiUty and character, such data as have
been presented from family histories and relationships are not en-
tirely convincing. It might be argued that a given family has
so many individuals of high or low intelligence and achievement
because its members were born in circumstances which did or did
not afford opportunities for development and training and for
achieving higher success. It might be said that the descendants of
the Edwards family were born and reared among favorable cir-
cumstances of educational and financial advantages and conse-
quently were fitted for greater tasks and lived in an environment
in which larger opportunities offered themselves, whereas the
members of such a lineage as the Jukes family would have just the
opposite environment of birth, education, and opportunity in life.
In answer to all this, we must remember, however, that ability
very largely determines the sort of environment in which a person
is satisfied to live, that a really capable person is quite likely to
push forward and to find a way out of the environment in which
he may happen to have been born, or to improve it if he cannot
leave it, and finally, we must remember that the persons of low
ability were born in circumstances of a correspondingly low nature
because of the hereditary stock of the families from which they
came. Their parents were content to live under the circumstances
under which they did live because their abilities and desires sought
for nothing better.

Similarities between Brothers and Sisters in Special Mental
Traits. Pearson has shown that the resemblance in physical
characteristics among brothers and sisters is approximately .50.
He gives the following coefficients of correlation for various
physical traits.

Brother and sister

Hair color : 55

Cephalic index 49

Height 50

Eye color 52



THE INHERITANCE OF MENTAL TRAITS 8l

What, however, is the degree of resemblance in mental traits?
The general argument is that mental traits are dependent upon
anatomical and neurological structures, and hence, if these are
inherited, mental traits must also be inherited. What is the evi-
dence from experimental and statistical facts?

In a study made by the writer ('17) a series of tests of capacities
directly affected by school work and another series of tests of capac-
ities not directly affected by school work were applied to 18 pairs
of brothers and sisters in the University of Wisconsin. Each test
was given twice on two different occasions in order to obtain a
fairly accurate measurement of the capacities concerned. The pur-
pose of giving the two types of tests was to ascertain whether
brothers and sisters were more alike in the traits affected by train-
ing than in the traits not directly affected by school training. The
following were the tests and the correlations obtained between
pairs of children of the same family :



TABLE 18
Correlations between abilities of brothers and sisters. After Starch ('17)



Reading — speed

Reading — comprehension .

Writing — speed

Writing — quality

Size of reading vocabulary .

Spelling

Arithmetical reasoning . . . .

Addition attempts

Addition — rights

Subtractions-attempts. . . .

Subtraction — rights

Multiplication — attempts .
Multiplication — rights. . . .

Division — attempts

Division — rights



Average .



Memory

A-test

Geometrical form test .
Tapping



Average

Coefficients based on ranks in all tests combined



51
ST

or

oT

3^-

jr

44^

43

29

37

25

46
56



82 EDUCATIONAL PSYCHOLOGY

In order to grasp the full import of these figures, it is necessary
to remember that the coefficient of correlation between mental
abilities of pairs of unrelated individuals selected by chance would
be zero, and that any coefiicient above zero between pairs of
brothers and sisters means a corresponding amount of resemblance.

"From the above table several interesting results appear, (i) The
resemblance of siblings is apparently no greater in those mental traits
which are directly affected by school work than in those which are not so
affected. The average correlation in the former group of tests is .42 and
in the latter .38. This seems to indicate that the mental similarities of
children of the same parents are due primarily to heredity rather than to
similarity of environment since the resemblance is no greater in those
traits which are more directly affected by environment.

" (2) The resemblance of siblings is approximately as great in mental
traits as in physical traits. Pearson found the correlation between
brother and brother in height to be .50 and in cephalic index (ratio of
length to width of head) .49. These correlations for physical traits are a
httle larger than the ones found here for mental traits taken separately.
The correlation, however, calculated on the basis of a combined rank for
each person in all mental tests together was found to be .73. This
greater correlation for all tests combined as compared with the correlation
for single traits is due partly to the variation of the correlations among
the single traits and partly due to the imperfections in the separate tests,
which are counterbalanced to some extent in a combined ranking."
(Starch '17, p. 237.)

Pearson ('04) made a comparison of 2,000 brothers and sisters
who were rated by their teachers in such traits as vivacity, self-
assertion, introspection, popularity, conscientiousness, temper,
abihty, and handwriting. On the basis of these ratings he found
coefiicients of correlation ranging from .43 to .64 with an average
of .52, These results are interesting and indicative of the resem-
blance of more general traits of character, but they are probably
rendered more or less uncertain by the unreliability of one person's
ratings of such elements of character. The likelihood is that the
teachers would be more inclined to estimate alike the children from
the same families, rather than to estimate them more different
than they really were.

Similarities of Brothers and Sisters in Abilities in School Sub-
jects. In a study made several years ago, Earle ('03) found a
correlation of .50 between the spelling abilities of iSo pairs of
brothers and sisters. The writer ('15) made a study of the scho-



i



THE INHERITANCE OF MENTAL TRAITS 83

lastic records of children from 63 families. The average grade in all
school subjects was obtained for each pupil and used as the measure
of his academic abiUty. The correlations based upon these averages
were as follows:

First and second child in a family, 63 pairs 58

Second and third child in a family, 24 jiairs 64

First and third child in a family, 24 pairs 34

Average 52

Further comparisons were made for abilities in specific school
subjects which yielded the following correlations:

Spelling, 57 pairs of children from the same parents 21

Reading, 57 i)airs of children from the same parents 49

Writing (speed) 24 pairs of children from the same j)arents 18

Writing (quality) 24 pairs of children from the same parents 06

Another study was made of t,8 children from 11 families. All the
marks that each pupil had received in each study in grades three to
eight were averaged. From these averages the following coefficients
of correlation were obtained.

Arithmetic, 54 pairs 32

Spelling, 54 pairs 21

Reading, 54 pairs 31

Language, 54 pairs 24

"No importance, I believe, can be attached to the differences in cor-
relation between the various studies. The correlation for individual
studies is lower than that for scholarship in general based on the average
performance in all studies combined. This is probably due chiefly to the
fact that the inaccuracies of teachers' marks in individual subjects are
partly eliminated in the averages derived from all studies.

"Abilities in special subjects are inherited, apparently, to no greater
extent in one subject than in another. What is probably inherited is
either general scholarship or else more specialized traits than ability in
arithmetic, or ability in language. Each study involves many mental
faculties and nearly all studies involve the same faculties with varying
emphasis.

"In corroboration of this point we may notice the following table of
average marks for each of nine families in each study.

"In this table, we must examine the ranks, rather than the marks, of
the difTerent families in each subject, so as to eliminate the variation in
standards of marking. These families rank very nearly the same in the



84



EDUCATIONAL PSYCHOLOGY



1



various studies. For example, family C is first in every study except
arithmetic and there it is third. Family G is second in every subject
except arithmetic and there it is fourth. Family I is either third or fourth
in every subject but one, and family B is last in every subject except one.



TABLE 19
Averages for each family in each subject.



I



Famtly



A.
B.

c.

D.

E.

F

G

H

I.





Arith-


Spelling


Reading


Language


Geog-


History


No. OF


metic








raphy




Children


Grade


Grade


Grade


Grade



Online LibraryDaniel StarchEducational psychology → online text (page 6 of 41)