Measuring Individual Differences in Achievement,
Aptitude, and Interest

It is difficult to avoid taking tests. Achievement tests are given almost daily in schools. Few people reach college without taking at least one intelligence test. College is by no means the last opportunity to take tests. When you choose a career, you may take aptitude tests and interest tests. Aptitude tests are sometimes used even for summer jobs.

As you read the text, try to answer the following questions.
How valid are aptitude tests?
What is the purpose of aptitude tests?
Why are interest tests given?
Is there any evidence that interest tests are valid?


Achievement tests measure past accomplishments

Achievement tests, as the name implies, are designed to measure how much a person has achieved or learned. The tests given in this course are examples of achievement tests. This history of comparative achievement testing can be traced back to the Boston Survey of 1845. In that year, Dr. Horace Mann had been appointed as secretary of the Massachusetts State Board of Education. After looking at the schools, he was appalled by the lack of consistent quality among various schools in Boston. Naturally when he made his views public there was a large outcry from the schools, each claiming that it was doing an adequate or superior job. As a result of this quarrel, it was decided to prepare a written examination of questions on arithmetic, history, geography, grammar, national philosophy, science, and so on. The tests consisted of 154 questions and were given to 530 pupils selected from the more than 7000 then attending the Boston schools. The results of the tests justified Mann's criticisms; many inequalities were revealed. Unfortunately the Boston experiment was soon forgotten and more than 50 years went by before any similar projects were undertaken. In recent years the practice of achievement measurement has greatly in- fluenced curriculum and methods in education. Achievement testing is becom- ing ever more important as the technology of teaching and evaluation become more refined and interrelated.


Suppose that two persons have the same opportunities to learn a skill. They attend the same classes, study the same material, and practice the same length of time. One of them acquires the skill easily; the other has difficulty and never really masters it. These two, then, differ in aptitude for this type of work. Long ago employers figured out that they could save a great deal of money by weeding out persons with low aptitudes before hiring them. In fact, aptitude tests were originally developed for this purpose.

Aptitude tests predict future accomplishments in a particular activity

Aptitude tests are used to predict success or failure in an undertaking. They are used to measure many different aptitudes such as mechanical ability, manual dexterity, motor coordination, and perceptual speed and accuracy. In future accomplishments, a general aptitude test is less satisfactory than a standard IQ test in predicting a particular activity performance in school or in jobs requiring particular types of intellectual activity.

To verify the validity of an aptitude test, the employer would have to give the test to a large number of applicants, then hire them all without regard to their scores on the test. The ranking of subjects on the aptitude test would then be correlated with the ranking based on performance on the job.

Even though the correlation between success on a single aptitude test and success on the job is usually low, aptitude tests are widely used. Today they are more likely to be used in batteries (a collection of tests) rather than alone. The results of a battery of aptitude tests provide much information about a person's pattern of abilities.

A process of factor analysis, much like the one Thurstone used, is involved in the construction of an aptitude test battery. Performances on the assorted tests in the battery can give valuable information about the aptitudes of the subject. In fact, Thurstone's test of primary mental abilities is sometimes used as an aptitude test battery. The General Aptitude Test Battery (GATB) is another test often used to evaluate likelihood of success. The GATB includes an intelligence test, general aptitude tests such as verbal ability and perceptual speed, and other tests oriented toward specific occupations. A person with an aptitude for repairing mechanical devices, for example, would score relatively high in intelligence, numerical ability, spatial ability, and finger dexterity.

Another aptitude test battery is the Differential Aptitude Test (DAT).

While the aptitude tests used by individual employers are usually quite specific (they test for one particular skill), the tests used in employment agencies and vocational guidance centers are more general. These are differential aptitude tests that measure several kinds of abilities and are often used for guidance in career selection.

The Army has used a general aptitude (intelligence) test called the AFQT to select recruits for different branches of the service. Scores form a normal distribution where the top 10% are classified as Category I and the bottom 10% as Category V (those rejected for service). During World War II they had to dip into Category IV for 21% of recruits. In the Vietnam War, however, in 1979, 46% of new recruits were from Category IV (Frum, 2000, p. 89)!


To succeed in a job, an individual must have more than an aptitude for the position. He must also have a pattern of interests that will allow him to enjoy it. Interest tests were developed to discover the subject's pattern of interests. His pattern can then be compared with interest patterns of successful persons in different occupations.

Interest tests provide comparisons of a subject's interests with those of successful people in various fields.

The Strong Vocational Interest Test is commonly used in counseling centers. The test was developed empirically. That is, it was based on research data rather than theory. Strong selected several hundred items which he thought might distinguish interests in different occupations. He then had several hundred people, who were chosen as representative of at least 50 different occupations, take the test to determine typical response patterns for each vocation. This test must be scored separately for each occupation such as accountant, artist, author, housewife, mathematician, social worker, and veterinarian.

Another interest test is the Kuder Preference Record, which uses the theoretical approach. This test divides all interests into nine categories: mechanical, computational, scientific, persuasive, artistic, literary, musical, social, and clerical. The counselor can compare the subject's scores with the different occupational norms and advise the student of the results. He might, for example, tell a student his interests correspond more with those of engineers and scientists than with those of teachers and salesmen.

The interest pattern of an individual remains relatively constant throughout his life (Strong, 1951). The data presented in Figure 17 also shows that interest patterns develop prior to actual experience in an occupation. Thus interest tests can be used in counseling centers and employment agencies.

50 College Freshmen 19 20 18
50 College Freshmen 19 38 .72
50 College Seniors 22 27 .84
228 College Seniors 22 44 .75

Figure 17. Constancy of interest patterns (After Strong. 1951)

One disadvantage of the use of interest tests in selecting occupations is that only people with common patterns of interests would be encouraged to pursue the occupation. A student who does not have the typical interest pattern of a mathematician, for example, may be discouraged from becoming one. Such procedures may, in the long run, stifle change and progress within any profession.


Now test yourself without looking back.

1. To predict success or failure in an undertaking is the purpose of a(n)_____________________

2. Tests of manual dexterity, coordination, and clerical ability are (apttude/interest)_____________________ tests.

3. The correlation between a single aptitude test and success in a particular occupation is:
a. higher than the correlation between 10 tests and success on the job.
b. generally above .50.
c. an excellent predictive device.
d. (none of these are necessarily true)

4. The Strong Vocational Interest Test is:
a. a vocational achievement test.
b. an interest test using the theoretical approach.
c. an interest test using the empirical approach.
d. (none of these)

5. An interest test would probably be given:
a. by a guidance counselor.
b. by an employment agency.
c. to select applicants for a particular position.

6. Which of these is the best definition of an achievement test?
a. A test that measures patterns of enjoyment in a person and compares them with representatives of a specific occupation.
b. A test used to predict success or failure on some future specific task.
c. A test that measures some previous learning.
d. A test that diagnoses mental disturbances.



An aptitude test is used to predict success or failure in an undertaking. Which of the following should be classed with aptitude tests?
a. A doctoral dissertation
b. A college entrance exam
c. A pre-employment test of manual dexterity
d. An interest inventory


An interest test is given to determine a person's pattern of interests. This pattern is then compared to those of persons in different occupations. An interest test might be given by:
a. an employment agency.
b. a vocational guidance counselor.
c. (neither)


A test used to predict success or failure in an undertaking is called________________________1

A test used to determine an individual's pattern of interests is called____________________________________6

The correlation between a subject s performance on a single aptitude test and his performance on the job has been found to be fairly low. Yet batteries of aptitude tests have good predictive value. Therefore:
a. aptitude tests should be used in groups if they are to be good predictors of success on the job.
b. an aptitude test should not be used alone in advising persons on a career.
c. aptitude tests should not be used at all.
d. aptitude tests are not reliable.



1) Aptitude test
2) Interest test

a. Might be given to applicants for specific occupation

b. Might be given by an employment agency or guidance center to help in selecting an occupation

c. Indicates whether a person might enjoy an occupation

d. Indicates whether a person might perform very well in an occupation _______________________________2

The Strong Vocational Interest Test was developed empirically. This means that the interest patterns of various occupations:
a. were determined theoretically.
b. were determined by collecting infommabon about persons in those occupations.
c. represent only very successful persons.
d. (none of these)


1. an aptitude test
1) a,b,d
2) a, b, c
3. a,b
4. a,b
5. b
6. an interest test
7. b,c
8. a,c



1. An aptitude test might be used to:
a. diagnose mental illness.
b. determine which person to hire as a programmer.
c. collect information about a person's pattern of interest.
d. (none of these)

2. Tests for intellectual, perceptual, and motor abilities are examples of _____________________.

3. Aptitude tests:
a. have some correlation with job success.
b. are useful in determining if a person will be successful in a career.
c. measure the interests of an individual.
d. are devised by collecting information about their preferences from people in differ-
ent occupations.

4. Match.
1) Aptitude test________________

2) Interest test _______________

3) Intelligence test_______________

a. Strong Vocational Interest Test
c. Stanford-Binet

5. A person applying for a specific position would be most likely to take:

a. an interest test
b. a personality test.
c. an aptitude test.
d. an IQ test.

6. A person who wants to know the type of occupation he wlil be most happy in would take a(n)_____________________________________________

7. An achievement test measures_______________________________________


Unit 7 Table of Contents

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October 10, 2004