Psychology- Chapter 9: Intelligence and Psychological Testing
Key Concepts in Psychological Testing
A psychological test is a standardized measure of a sample of
a persons behaviour. They are used to measure the individual
differences that exist among people in abilities, interests,
and aspects of personality.
Responses to a psychological test represent a sample of your
Principal Types of Tests
Psychological tests are used extensively in research, but most
of them were developed to serve a practical purpose outside of
Most tests can be placed in one of two broad categories:
mental ability tests and personality tests.
Mental Ability Tests
Intelligence tests measure general mental ability. Theyre
intended to assess intellectual potential rather than previous
learning or accumulated knowledge.
Aptitude tests are also designed to measure potential more
than knowledge, but they break mental ability into separate
components. Thus, aptitude tests assess specific types of
For example, the Differential Aptitude Tests assess verbal
reasoning, numerical ability, abstract reasoning, perceptual
speed, and accuracy, mechanical reasoning, space
relationships, spelling and language usage.
Like aptitude tests, achievement tests have a specific focus,
but theyre supposed to measure previous learning instead of
potential. Thus, achievement tests gauge a persons mastery
and knowledge of various subjects (such as reading, English,
Personality tests measure various aspects of personality,
including motives, interests, values, and attitudes.
Many psychologists prefer to call these tests personality
scales because the questions do not have right and wrong
Standardization and Norms
Standardization refers to the uniform procedures used in the
administration and scoring of a test.
All subjects get the same instructions, the same questions,
and the same time limits so that their scores can be compared
Test norms provide information about where a score on
psychological tests ranks in relation to other scores on that
test. Test norms are needed since everything in psychological
tests are relevant. Psychological tests tell you how you score
relative to other people. A percentile score indicates the percentage of people who
score at or below the score one has obtained.
The sample of people that the norms are based on is called a
tests standardization group.
Ideally, tests norms are based on a large sample of people who
were carefully selected to be representative of the broader
Reliability refers to the measurement consistency of a test
(or of other kinds of measurement technique).
A tests reliability can be estimated in several ways. One
widely used approach is to check test-retest reliability,
which is estimated by comparing subjects scores on two
administrations of a test.
A correlation coefficient is a numerical index of the degree
of relationship between two variables. In estimating test-
retest reliability, the two variables that must be correlated
are the two sets of scores from the two administrations of the
test. The closer the correlation comes to +1.00, the more
reliable the test is.
Validity refers to the ability of a test to measure what it
was designed to measure.
The term validity is also used to refer to the accuracy or
usefulness of the interferences or decisions based on a test.
This broader conception of validity highlights the fact that a
specific test might be valid for one purpose and invalid for
Content validity refers to the degree to which the content of
a test is representative of the domain its supposed to cover.
Content validity is evaluated with logic more than with
Criterion-related validity is estimated by correlating
subjects scores on a test with their scores on an independent
criterion (another measure) of the trait assessed by the test.
Construct validity is the extent to which there is evidence
that a test measures a particular hypothetical construct.
Demonstrating construct validity can be complicated. It
usually requires a series of studies that examine correlations
between the test and various measures related to the trait in
question. A thorough demonstration of construct validity
requires looking at the relationship between a test and many
The Evolution of Intelligence Testing
Galtons Studies of Hereditary Genius In Galtons book Hereditary Genius, Galton concluded that
success runs in families because great intelligence is passed
from generation to generation through genetic inheritance.
He assumed that the contents of the mind are built out of
elementary sensations, and he hypothesized that exceptionally
bright people should exhibit exceptional sensory acuity.
His efforts met with little success. Research eventually
showed that the sensory processes that he measured were
largely unrelated to other criteria of mental ability that he
was trying to predict, such as success in school or in
The Binet-Simon scale expressed a childs score in terms of
mental level or mental age.
A childs mental age indicated that he or she displayed the
mental ability typical of a child of that chronological
Binet realized that his scale was a somewhat crude initial
effort at measuring mental ability. His death put an abrupt
end to revising his scale, but other psychologists continued
to build on Binets work.
Terman and the Stanford-Binet
An intelligence quotient (IQ) is a childs mental age divi