THE DEVELOPMENT OF PSYCHOLOGICAL TESTS
ORIGIN AND HISTORY OF TESTS
Barren as phrenology and physiognomics were of formulable and useful
results, they nevertheless served the purpose of directing attention toward
the study of individual differences in mental characteristics as a distinct
branch of inquiry. The next step consisted in the semi-experimental plan of
observing the individual's _behavior_ under a variety of uncontrolled
circumstances or on more carefully planned occasions, in the endeavor to
secure more or less exact quantitative expressions of the degree to which
he displayed certain types of ability. Underlying the various abilities and
involved in them there were assumed to lie a limited number of faculties or
powers of the mind. Each individual was conceived to possess much the same
faculties, but in varying degrees or amounts or forms. Attention, memory,
apperception, reasoning, will, feeling, etc., were the fundamental
"faculties"; and differences in character were thought of as depending upon
the varying amounts and interrelations of these fundamental faculties. In
the endeavor to discover types of experiment which would measure these
"faculties" it was found, in time, that a given "faculty" did not appear,
on close examination, to be as unitary as it was formerly supposed to be.
It was seen that to have a good memory for one kind of material did not at
once signify a good memory for every sort of thing. Determination in one
direction did not imply the general quality of resoluteness. It began to be
realized that attention, memory, discrimination, and the other "faculties"
are very much more highly specialized than these general names indicate.
The unitary soul had early been split up into the list of "faculties" or
categories, and now these in turn came each to be split up into finer and
finer aptitudes and tendencies, until, in the radical reaction of recent
years, we find the human mind described as made up of an infinite number of
independent connections or bonds between more or less specific stimulus and
more or less definite response. The old "faculties" came now to be looked
on as descriptive terms for certain rather general and abstracted
characteristics of these multitudinous and detailed reaction tendencies,
rather than as in themselves agents or powers or forces, as they were
formerly conceived.
During this change in theoretical description and continuing into our
present era of compromise and revision, methods were developed of measuring
the amount and quality, or, more simply conceived, the speed, strength and
regularity of mental and motor ability. Beginning in the form of
experiments on sensory discrimination, reaction time and imagery type, and
combined with physiological measurements of motor strength, rapidity and
fatigue, these experiments developed, in certain hands, into what are now
known as "mental tests." Since the principle and method of mental and
physical tests is the chief characteristic of the present status of
vocational psychology, and since the work of the immediate future seems
destined to develop mainly in this same direction, we may profitably
consider at this point the history and development of the mental test. We
may later take up the general principle and theory of the test as an
instrument of psychological analysis and diagnosis, with special reference
to the requirements and implications of such tests as may be of service in
vocational psychology. We shall then be in position to review the special
vocational tests that have as yet been proposed, to evaluate their
outstanding results, and to point to some of the more immediate prospects
and problems under consideration by those interested in the application of
psychological tests in vocational analysis and guidance.
We may begin with an account of the first definite attempt to explore
systematically the personality of individuals by the method of tests. The
"Columbia Freshman Tests" are of especial interest in the history of
vocational psychology, since in their formulation and plan explicit thought
was given to the practical use to which the results of tests might be put
by the individuals examined, and by the statistical study of the results by
students of the subject. In 1894, under the guidance of Professor Cattell,
there was instituted the plan of testing the students of Columbia College
during their first and fourth academic years. A description of the tests
employed was published by Cattell and Farrand in 1896, and a statistical
study of results was published by Wissler in 1901.
The motive back of these tests is well expressed in the following paragraph
which was also used as material for a test of logical memory:
"Tests such as we are now making are of value both for the advancement of
science and for the information of the student who is tested. It is of
importance for science to learn how people differ and on what factors these
differences depend. If we can disentangle the complex influences of
heredity and environment we may be able to apply our knowledge to guide
human development. Then it is well for each of us to know in what way he
differs from others. We may thus in some cases correct defects and develop
aptitudes which we might otherwise neglect."
The nature of these Columbia tests and the method of recording and
reporting them are indicated in the forms which were printed and used for
this special purpose. (Samples of these are given in the Appendix.) They
are given here not so much for the sake of the enumeration of the tests,
since many of these are no longer in common use, but because of their
historic interests for vocational psychology and because of the general
plan outlined in them. In general this plan is that of accumulating
measurements of a large number of individuals and thus showing each one how
he compares with the normal or average, or where he stands in the general
curve of distribution of the members of the group. These tests were applied
to the same individuals on their entrance to and their graduation from
college, in order to indicate changes that might have been made during the
intervening period.
Especially interesting also are other blanks containing additional data,
such as age, health, physical characteristics, physiognomic features,
enumeration of stigmata, etc. In addition to the tests and measurements,
the examiner, both before and after the interview, recorded his general
impression of the individual, in the terms indicated on the blank form. We
shall have occasion to refer to these judgments of general impression in
more detail when we come to consider the use of the interview and the
testimonial in vocational psychology. Account was also taken of the
gymnasium records of the student, as to nationality, birth, parentage,
habits, health, etc.
The Columbia tests may be thought of as representative of several similar
projects developed in this country and in Germany, France and England by
many workers. The names of Galton, Cattell, Kraepelin, Binet, Henri, and
Jastrow stand out conspicuously in the early history of mental tests. The
first step was thus the invention, description and trial of a great number
of miscellaneous tests, with little analysis of the tests themselves, the
nature of the functions tested by them, or their relation to each other.
Aside from the strictly motor and physical tests those devised were mainly
of so-called intellectual character: measurements of speed and accuracy
with which certain definite tasks could be accomplished. They were,
moreover, very simple in character, not necessarily related to the work of
daily life, with only a single or but a few trials made on each individual.
Tests of affective and volitional factors were slower in developing. Little
account was taken of interests, instinctive and emotional characteristics,
attitudes, adaptation, methods of attack, limits of ability after practice,
or many other aspects of individuality which later work has shown to be
important.
The next step in the development of tests consisted in the cooperative
effort to standardize the nature and methods, the conditions and mode of
record. Many hands had part in this process, until in recent years, through
publication, comparison and discussion of the subject, fairly uniform
principles of technique, record, and treatment of measures have been agreed
upon. This made possible the comparison of results secured by different
investigators, and facilitated the statistical treatment of the data, so
that later work might profit by what had already been tried or accomplished
by earlier workers. After many years of this sort of cooperative work,
another series of studies was inaugurated to attempt what has come to be
known as "testing the tests." These studies proceeded by examining into the
degree to which the various tests correlate with each other, with other
indications of the individual's ability, with age, sex, health, education,
school standing, special training, etc. Such questions as the following
will suggest the problems involved in "testing the tests."
1. Which of the various tests correlate with each other?
2. What correlation exists between mental and motor abilities?
3. Do the tests measure fundamental qualities or general powers of the
individual, or specialized capacities, or perhaps mainly the effect of
general or special training?
4. If they measure general qualities, which of the existing tests are the
best for this purpose?
5. How many trials are needed to afford a reliable index of the
individual's ability?
6. What are the principal incidental factors that influence the result of
tests?
7. Which tests are most easily influenced or disturbed by extraneous
factors?
8. Can tests of the simpler laboratory type be used to indicate the
individual's ability as shown in his daily work and play?
9. How simple or complex should the various tests be in order to give the
best results?
10. How many tests, and which, are required to give a fairly correct
picture of the individual's psychological make-up?
11. To what degree do preliminary trials indicate the final capacity of an
individual?
12. Does the intercorrelation of tests change in any way with practice,
repetition, and familiarity with the material?
13. Just what mental functions may the particular tests be said to measure?
14. How important are these functions in practical, educational and
vocational life?
15. By what amounts and in what various ways do individuals differ among
themselves in such abilities as the tests measure?
16. Are there other important aspects of psychological constitution and
equipment for which there now exist no adequate tests?
The investigation of these numerous problems has resulted in the
accumulation of a considerable literature of mental tests. Many of the
earlier forms of tests were abandoned because of their unsatisfactory or
meaningless character. Others have been retained and improved in form, and
many new ones are constantly being devised and elaborated, described and
standardized. The precautions to be observed, the instructions to be given,
and the methods of record and interpretation have been presented in various
books and manuals. The tests have been developed for more and more complex
functions, and now relate not only to relatively simple capacities but to
highly elaborate and subtle forms of achievement. As rapidly as is
consistent with accuracy, norms and standards of performance for different
ages, school grades, vocational requirements, etc., are being accumulated
and reported. Typical charts of age norms in selected tests are given in
the Appendix.
As the tests have thus developed they have been organized for a variety of
special purposes, such as for school measurement, educational diagnosis,
clinical examination, laboratory experiment, and more recently for the
purposes of vocational guidance and selection. Among the first of these to
develop systematically, and also the ones with the most immediate
vocational application, are the graded intelligence scales, which shall be
our next concern.
GRADED INTELLIGENCE SCALES AND NORMS
An important step in the history of general tests is represented by the
accumulation of norms and standards of performance for the different
selected tests, and the arrangement of scales of tests with increasing
difficulty, as further aids in fixing the individual's status.
After a standardized and tested form of test has been selected, norms of
performance are accumulated by applying the test to large numbers of
persons of the same general type. The classification may be on the basis of
age, school grade, occupation, nationality, etc. In this way it becomes
possible to determine for a given individual how he compares with other
members of his group; whether he is above or below the average, and how
far; whether he would belong among the best ten, or the poorest ten, or the
third ten, etc., of one hundred selected at random. Such norms also reveal
to what degree the tested ability varies with the other factors, on the
basis of which the group was selected, as age, sex, education, size,
health, race, etc.
As rapidly as reliable norms are established, it becomes possible to select
for each age, school grade, occupation, etc., a set of tests which the
average person of that age, schooling or calling should be able to perform
to a certain known degree of proficiency. Failure to accomplish this
indicates performance lower than that expected and in so far as success is
dependent solely on mental ability, indicates inferior capacity. Similarly,
ability to do more than the average or normal record requires indicates a
capacity that is precocious, rare, and superior.
In this way are derived standard graded scales which represent a decided
advance in the science of psychological diagnosis. There are three rather
different forms in which attempts have been made to secure such scales. In
one form the scale consists of a series of steps, each step consisting of
different sorts of performance; that is, different tests or tasks are used.
These tasks are arranged in groups, each group representing tests which
should be passed acceptably by individuals of the given age, school grade,
etc. In another form of scale the type of task is the same throughout, but
the different points on the scale are represented by increasingly difficult
specimens of material. The scale thus presents graded steps of difficulty
in doing the same general sort of thing. In the third form the task remains
precisely the same throughout, and performance is measured in terms of the
time in which the task can be completed and the accuracy which is
displayed. Sometimes, in scales of this type, although the instructions are
always the same, the test is performed with varying degrees of
approximation to a qualitative standard, and the steps may then consist of
these graded qualitative achievements.
As representative of the first form of scale we may refer to the widely
used Binet-Simon scale for the determination of mental age. Whatever we
mean by intelligence, it is a characteristic which is essential to
vocational activity. It is furthermore a characteristic which normally
tends to increase in its degree or manifestation from infancy up to at
least ten or twelve years of age. Beyond that point there are, to be sure,
striking individual differences in that characteristic which we call
intelligence, but beyond this point it does not seem so dependent on the
physical age of the organism. Five-year-old children tend to be pretty much
alike in intelligence. At least, the change from five years to seven years
is commonly attended by very apparent growth in this respect, and a
five-year-old is more like other five-year-olds in the things he can do
than he is like seven-year-olds.
Experiment and observation show that the ages up to ten or twelve tend to
indicate rather definite mental status, in the long run, although, to be
sure, children of a given age vary considerably from one another. But
beyond this point the age of an individual is not by any means an
indication of the sort or degree of ability to be expected of him. The
further we go beyond this point, the less significant becomes the mere
statement of the individual's age. We may thus indicate the mental
attainment of a child of less than twelve years by stating the average age
of children who can do the things, know the facts, display the abilities
that he can. This figure we will use to indicate his _mental_ age as
distinguished from his _chronological_ or _physical_ or _actual age_. A
record-blank which enumerates the tests comprising the Binet-Simon scale is
given in the Appendix. Those who may be interested in using this or similar
scales should familiarize themselves with some of the many books and
manuals that have been written concerning them, the methods of using them,
their characteristic results and their evaluation. These scales will be
again considered in a later section, when we discuss the measures of
general intelligence as they relate to vocational guidance and selection.
Other scales than the Binet-Simon series have been proposed, and this
series has itself undergone modifications at the hands of later
investigators--changes calculated to render it more reliable and adaptable.
Much work is now being done in the attempt to develop scales or sets of
tests which will reveal characteristic differences among people whose
mentality has gone beyond the point which the juvenile scales reach.
The work of Trabue in standardizing the "completion test" so that
individuals may be quantitatively compared on the basis of it may serve as
an example of the second form of scale. This particular test consists in
requiring the individual to supply meaningful words or phrases in the blank
spaces formed by mutilating logical text. It is similar to the simple
exercise sometimes found in elementary text books of grammar and spelling.
It seems that the ability to supply the missing words or phrases quickly in
such mutilated material calls for the exercise of a type of ability which
correlates to a high degree with most other measures of intelligence.
Individual differences as shown by school grades, age, opinion of teachers,
estimates of associates, results of other mental tests, etc., are readily
and with considerable reliability revealed in the individual's ability to
perform this type of test. This investigator has, after much preliminary
labor, constructed a form of this test in which the material gradually
increases in difficulty from beginning to end. Efficiency in the test may
be measured by the point one can reach in the text in a given time. This
test has been standardized, not on the basis of physical age, as in the
case of the Binet-Simon scale, but on the basis of school grade, from the
second grade through the high school, some four or six years beyond the
point where the Binet-Simon scale ceases to be useful. A copy of this test
is also given in the Appendix. Those who wish to use it should consult the
original description of it, for technique, precautions, norms, and
interpretation.
A good example of the third form of scale is to be found in Sylvester's
standardization of the "form-board" test. The "form-board" is one of the
most useful tests in detecting intellectual defect that is so pronounced as
to constitute the individual a "mental defective." Out of a solid base
board are cut various geometrical forms, such as diamonds, stars, squares,
triangular blocks, etc. These blocks are placed alongside the base from
which they have been cut. The task is that of replacing all the blocks in
their appropriate places, with the greatest possible speed. The test tends
to reveal characteristic defects in understanding instructions, perceiving
the general and specific situations, profiting by experience, recognizing
form and size and other space relations, etc. The individual may work
blind-folded or may use his eyes.
In the standardized form the sizes, shapes and positions are uniformly
adopted and the technique of instruction and procedure is specified. Under
these conditions the time required to complete the task by normal children
of the ages five to fourteen years has been recorded. Sylvester presents a
curve based on the examination of 1,537 normal children. The curve shows
the average time of performance for each age and also indicates the range
of performance for each age. In the case of a given individual it is thus
easy, by referring to the standard table of norms, to determine whether he
is up to the normal record for his age, whether he is within the normal
range of variation for this age, and how deficient or precocious he may be
in this respect. Tables of this type are now being accumulated for a great
variety of single standard tests.
In addition to scales of this type, which proceed by setting for the
individual a graded series of tasks and determining his success in their
accomplishment, there is a further type of graded scale which is now
represented by several standard specimens. This is the type of scale which
is designed to afford an instrument for the measurement of such products as
the actual work of the individual incidentally yields. Thorndike's "Scale
for the Measurement of Handwriting" is the model on which many of the later
scales of this type have been based. In this scale actual specimens of
handwriting are arranged in a graduated series in such a way that the steps
from specimen to specimen are equally appreciable or noticeable, and in
this sense uniform. When such a scale extends from an actual zero point, it
is possible to "measure" the quality of handwriting in quite the same way
as that in which one measures the height of an individual or the length of
a table. The quantitative measure consists in the statement of the number
of stages which intervene between that quality of product represented by
the specimen and the zero point of the scale. The position assigned to the
specimen being measured is determined by moving the specimen along the
graded series of standards until a point is reached where the specimen
seems, on the basis of direct inspection, to belong. Such scales have been
formulated for various special forms of school work, such as handwriting,
drawing, arithmetic, literary composition, mechanical construction, etc. By
such means it is possible not only to measure the "general intelligence" of
the worker, but also his actual ability in creating a definite type of
product. There seems to be no limit to the possibilities of scales of this
form, and their value in determining the more definite and particular
capacities, whether from the point of view of original endowment or from
the point of view of the effects of training, is obvious.
These various scales for measuring general intelligence have been used
chiefly for the purposes of educational diagnosis, in determining the
degree of backwardness of children in the grades, their need for special
educational attention, or the hopelessness of further pedagogical effort
with them. But it is obvious at once that tests of this type are of great
use to an employer in eliminating, from among the candidates for work,
those who are hopelessly mentally defective, feeble-minded, and
irresponsible. There are many sorts of work in which the employment of
feeble-minded persons, unrecognizable as such by their physical traits or
by a casual inspection, not only entails loss and annoyance but may
constitute a positive danger and constant menace to those who rely on the
defective individual. Such work as that of delivery boys, messengers,
domestic servants, nurses, elevator operators, drivers, motormen, etc., may
be cited as instances of work into which the feeble-minded easily slip,
unless there is some standardized means of recognizing them.
The importance of detecting these incompetents and keeping them from work
in which their irresponsibility means economic waste and personal and
social danger is of distinct vocational interest. Studies of cases brought
to the Clearing House for Mental Defectives in New York City show that of
the first two hundred and eighty-one feeble-minded women of child-bearing
age, about two-thirds had been engaged in some form of economic labor in
which their incompetence was distinctly dangerous to those associated with
them. The following table shows how these two hundred and eighty-one
feeble-minded women had been employed:
Living at home and assisting at simple tasks 94
Domestic service (families, bars, hotels, etc.) 67
Engaged in factory operations 21
Living in institutions, reformatories, asylums 20
Prostitutes 30
Laundresses 5
Working in stores, clerking, errands, etc. 5
Nursemaids 9
Odd jobs 6
Married and keeping house 11
Housework, with relatives 13
The investigators originally reporting these data write as follows: "These
defective women had borne eighty-nine illegitimate children, which were
acknowledged and could be somewhat definitely located, and sixteen women
were illegitimately pregnant at the time of their examination at the
Clearing House. Twenty-four of the two hundred and eighty-one had married
and these had borne forty-six legitimate children. The average mental age
of the illegitimate mothers was nine years."
The employment of feeble-minded women as domestics, factory operatives,
laundresses, clerks, and nursemaids constitutes not only a nuisance to the
general public, but a real source of inefficiency and danger to the
community. Graded scales for the measurement of intelligence will have
amply repaid the labor devoted to their formulation if they aid us in the
proper segregation and vocational supervision of the mentally defective.
The feeble-minded boy is more likely to be observed in the natural course
of things, because of the more strictly competitive types of work into
which boys customarily go, but it is far from realized how much loss of
property, life, and general happiness is entailed upon the community by the
indiscriminate employment of untested boys and men as floating employees.
But the vocational value of the graded intelligence scales and norms is not
limited to the work of detecting and eliminating the feeble-minded. Many of
the tests as now standardized yield measures of intelligence, capacity and
comprehension ranging far above the level which constitutes the borderline
of mental defect. Some of them reach somewhat higher than the average
intelligence and capacity of the college freshman. It is thus possible,
through the use of the graded scales, to measure in quantitative terms the
general intelligence as well as various more special capacities of
applicants and candidates for positions for which general intelligence is
the chief requisite. Such tests are now used in many places in the
selection of clerical workers, telephone operators, stenographers,
waitresses, motormen, salesmen, office help, inspectors, watchmen,
soldiers, and special types of factory workers. Thus Trabue reports a study
in which Professor Scott tested thirty efficiency experts employed by a
large industrial concern in New England. Ten psychological tests were used,
including a completion test. The men were also judged on the basis of
their relative abilities by the members of the firm. The combined tests
correlated with the combined judgments, giving the very high coefficient of
.87. The completion test alone yielded a coefficient of .64. From the point
of view of vocational selection we may expect the principle of the graded
intelligence scale to become increasingly valuable as more and more norms
are established. The first definite contribution of vocational psychology
is thus not so much toward the guidance of the individual worker as for the
guidance of the employer who may be required to select from a number of
applicants those whose general intellectual equipment is most adequate. But
we shall later have occasion to point out a further contribution which this
makes possible, in so far as it may enable us to classify the operations
involved in various types of work and to align these operations and tasks
along the general intelligence scale. Such alignment will enable us to
specify the approximate degree of general intelligence which a given
position demands, and thus, in the case of the simpler tasks, afford a
means of vocational guidance as well as vocational selection.