Chapter 11.pdf

chapter

Intelligence

THEME:

Measuring intelligence is

worthwhile, but tests

provide limited deﬁ nitions

of intelligent behavior.

Key Questions

How do psychologists deﬁ ne intelligence?

What does IQ tell us about genius?

What are the qualities of a good psycho-

logical test?

What causes mental retardation?

How do heredity and environment affect

intelligence?

What are typical IQ tests like?

How do IQ scores relate to gender, age,

and occupation?

How have views of intelligence changed

in recent years?

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Preview

What Day Is It?

The striking contrast between George’s general

retardation and his unusual ability is a ﬁ tting introduction

to the challenge of trying to deﬁ ne and measure

intelligence. Quite frankly, we are still searching for answers

to questions like these: Is intelligence a general trait or a

collection of speciﬁ c skills? Is intelligence affected by the

genetic “wheel of fortune”? How much is it nurtured by

environment? Is it possible to create an intelligence test

that is fair to all people? How important is intelligence for

“success”? Because our understanding of intelligence is

rapidly changing, we cannot hope to give ﬁ nal answers to

all these questions.

For the sake of clarity, let’s ﬁ rst assume that intelligence

can be measured. That way, we can use IQ scores to

answer some important questions about intelligence.

Later, we will consider questions that have been raised

about intelligence tests and the meaning of their results.

Ask George, “In which recent years did April 21 fall on a

Sunday?” With little hesitation he will answer, “2002, 1996,

1991, 1985, 1974, 1968, 1963, 1957, 1946.” Surprisingly,

this gives only a hint of his ability. If encouraged, George

will go back as far as 1700—with complete accuracy!

His calendar calculations cover at least 6,000 years: With

equal ease he can identify February 15, 2002, as a Friday

or August 28, 1591, as a Wednesday.

Is he a genius? George’s abilities are even more amazing

because he is mentally retarded. George cannot add,

subtract, multiply, or divide even simple numbers (Horwitz

et al., 1965). His strange talent is an example of the savant

syndrome, in which an island of brilliance is found in a sea

of retardation. In the savant syndrome, a person of limited

intelligence shows exceptional mental ability in a narrow

area, such as mental arithmetic, calendar calculations, art,

or music (Miller, 1999; Treffert, 2000).

Deﬁ ning Intelligence—Intelligence

Is . . . You Know, It’s . . .

Anne is considered a genius; Billy, a slow learner. There seems lit-

tle doubt that they differ in intelligence.

Wait! Anne’s ability is obvious, but how do we know that Billy isn’t

just lazy? This is the same question that Alfred Binet faced in 1904

(Jarvin & Sternberg, 2003). The minister of education in Paris had

asked Binet to ﬁ nd a way to distinguish slower students from the

more capable (or the capable but lazy). In a ﬂ ash of brilliance,

Binet and an associate created a test made up of “intellectual”

questions and problems. Next, they learned which questions an

average child could answer at each age. By giving children the

test, they could tell if a child was performing up to his or her po-

tential (Kaufman, 2000).

Binet’s approach gave rise to modern intelligence tests. At the

same time, it launched nearly 100 years of heated debate. Part of

the debate is related to the basic difﬁ culty of deﬁ ning intelligence

(Sternberg, Grigorenko, & Kidd, 2005).

Intelligence cannot be seen, it has no mass, and it occupies no

space. Nevertheless, we feel certain it exists. Let’s compare two

children:

When she was 14 months old, Anne H. wrote her own name. She

taught herself to read at age 2. At age 5, she astounded her kindergar-

ten teacher by bringing a notebook computer to class—on which she

was reading an encyclopedia. At 10 she breezed through an entire

high school algebra course in 12 hours.

Billy A., who is 10 years old, can write his name and can count, but

he has trouble with simple addition and subtraction problems and ﬁ nds

multiplication impossible. He has been held back in school twice and is

still incapable of doing the work his 8-year-old classmates ﬁ nd easy.

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364

CHAPTER 11

Special

aptitude tests

Multiple

aptitude tests

Intelligence tests

RANGE OF ABILITIES

● Figure 11.1 Special aptitude tests measure a person’s potential for

achievement in a limited area of ability, such as manual dexterity. Multiple

aptitude tests measure potentials in broader areas, such as college work, law,

or medicine. Intelligence tests measure a very wide array of aptitudes and

mental abilities.

Modern intelligence tests are widely used to measure cognitive abilities.

When properly administered, such tests provide an operational deﬁ nition of

intelligence.

Deﬁ ning Intelligence

Is there an accepted deﬁ nition of intelligence? In general, intelligence

is the global capacity to act purposefully, to think rationally, and

to deal effectively with the environment. Intelligence also in-

volves reasoning, problem-solving ability, knowledge, memory,

and successful adaptation to one’s surroundings (Sternberg,

2004). Beyond this there is much disagreement. In fact, many

psychologists simply accept an operational deﬁ nition of intelli-

gence, by spelling out the procedures they use to measure it. Thus,

by selecting test items, a psychologist is saying in a very direct

way, “This is what I mean by intelligence.” A test that measures

memory, reasoning, and verbal ﬂ uency offers a very different deﬁ -

nition of intelligence than one that measures strength of grip,

shoe size, length of the nose, or the person’s best Super Mario

Brothers video game score.

Driver

1. If the driver turns in the direction shown, which

direction will wheel Y turn? A B

2. Which wheel will turn the slowest? Driver

X Y

● Figure 11.2 Sample questions like those found on tests of mechanical

aptitude. (The answers are A and the Driver.)

graduate schools of law, medicine, business, and dentistry. The

broadest aptitude measures are general intelligence tests, which

assess a wide variety of mental abilities (Cohen & Swerdlik,

2005).

Aptitudes

As a child, Hedda displayed an aptitude for art. Today, Hedda is a

successful graphic artist. How does an aptitude like Hedda’s differ

from general intelligence? An aptitude is a capacity for learning

certain abilities. Persons with mechanical, artistic, or musical ap-

titudes are likely to do well in careers involving mechanics, art, or

music, respectively ( ● Figure 11.1).

Are there tests for aptitudes? How are they different from intelligence

tests? Aptitude tests measure a narrower range of abilities than in-

telligence tests do. For example, special aptitude tests predict

whether you will succeed in a single area, such as clerical work or

computer programming ( ● Figure 11.2). Multiple aptitude tests

measure two or more types of ability. These tests tend to be more

like intelligence tests. The well-known Scholastic Assessment Test

(SAT), which measures aptitudes for language, math, and reason-

ing, is a multiple aptitude test. So are the tests required to enter

Reliability and Validity

Suppose that a deranged psychologist, Professor Ike Q. Tester, de-

cides to write an intelligence test (the I. Q. Tester IQ Test ). As a

concerned citizen, there are two questions you should ask about

Tester’s test: “Is it reliable ?” and “Is it valid ?”

BRIDGES

Psychologists use a variety of aptitude tests to select people

for employment and to advise people about choosing careers.

See Chapter 20, pages 664–665.

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Intelligence

365

What does reliability refer to? If you weigh yourself several times

in a row, a reliable bathroom scale gives the same weight each

time. Likewise, a reliable test must give approximately the same

score each time a person takes it. In other words, the scores should

be consistent and highly correlated. It is easy to see why unreliable

tests have little value. Imagine a medical test for pregnancy or

breast cancer, for instance, which gives positive and negative re-

sponses for the same woman on the same day.

To check the reliability of the I. Q. Tester IQ Test, we could give

it to a large group of people. Then each person could be tested

again a week later to establish test-retest reliability. We also might

want to know if scores on one half of the test items match scores

on the other half (split-half reliability). If Professor Tester decides

to offer two versions of his test, we could compare scores on one

version to scores on the other (equivalent-forms reliability).

By comparing such scores we ﬁ nd that the Tester Test is quite

reliable. In fact, the scores are identical each time the test is given:

Everyone scores zero (except Professor Tester, who scores 100 per-

cent and thereby proclaims himself the only human with any in-

telligence).

Let’s concede to Tester that his test is reliable (but for the wrong

reasons). A more important question then becomes, “Is the test

valid?” Now Tester becomes testy. He knows his test is invalid and

that it will have to be withdrawn.

Obviously we have been playing with a silly example. A test

has validity when it measures what it claims to measure. By no

stretch of imagination could a test of intelligence be valid if the

person who wrote it is the only one who can pass it.

How is validity established? Validity is usually demonstrated by

comparing test scores to actual performance. This is called crite-

rion validity. Scores on a test of legal aptitude, for example, might

be compared to grades in law school. If high scores correlate with

high grades, or some other standard (criterion) of success, the test

might be valid. Unfortunately, many “free” tests you will encoun-

ter, such as those found in magazines and on the Internet, have

little or no validity.

Later in this chapter we will address the question of whether

intelligence tests are valid. For now, let’s take a practical approach

and learn about some popular standardized tests.

Testing Intelligence—The IQ and You

American psychologists quickly saw the value of Alfred Binet’s

test. In 1916, Lewis Terman and others at Stanford University

revised it for use in North America. After more revisions, the

Stanford-Binet Intelligence Scales, Fifth Edition continues to be

widely used. The original Stanford-Binet assumed that a child’s

intellectual abilities improve with each passing year. Today, the

Stanford-Binet (SB5) is still primarily made up of age-ranked ques-

tions. Naturally, these questions get a little harder at each age

level. The SB5 is appropriate for people from age 2 to 90 years and

scores on the test are very reliable (Roid, 2003).

Five Aspects of Intelligence

The SB5 measures ﬁ ve cognitive factors (types of mental abilities)

that make up general intelligence. These are ﬂ uid reasoning, knowl-

edge, quantitative reasoning, visual-spatial processing, and working

memory. Each factor is measured with verbal questions (those in-

volving words and numbers) and nonverbal questions (items that

use pictures and objects). Let’s see what each factor looks like.

Fluid Reasoning

This factor tests reasoning ability with questions like the following:

How are an apple, a plum, and a banana different from a beet?

An apprentice is to a master as a novice is to an ____________.

Intelligence An overall capacity to think rationally, act

purposefully, and deal effectively with the environment.

Operational deﬁ nition The operations (actions or procedures)

used to measure a concept.

Aptitude A capacity for learning certain abilities.

Special aptitude test Test to predict a person’s likelihood of

succeeding in a particular area of work or skill.

Multiple aptitude test Test that measures two or more

aptitudes.

General intelligence test A test that measures a wide variety

of mental abilities.

Reliability The ability of a test to yield the same score, or

nearly the same score, each time it is given to the same person.

Validity The ability of a test to measure what it purports to

measure.

Objective test A test that gives the same score when different

people correct it.

Test standardization Establishing standards for administering

a test and interpreting scores.

Norm An average score for a designated group of people.

Tester’s Last Stand

Let’s return to Professor Tester for a ﬁ nal point. Although he ad-

mits that his test has problems, Professor Tester claims that at least

it is objective. Is he right? Actually, he might be. If the I. Q. Tester IQ

Test gives the same score when corrected by different people it is

an objective test. However, objectivity is not enough to guaran-

tee a fair test. Useful tests must also be standardized.

Test standardization refers to two things. First, it means that

standard procedures are used in giving the test. The instructions,

answer forms, amount of time to work, and so forth, are the same

for everyone. Second, it means ﬁ nding the norm, or average

score, made by a large group of people like those for whom the

test was designed. Without standardization, we couldn’t fairly

compare the scores of people taking the test at different times.

And without norms, there would be no way to tell if a score is

high, low, or average.

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366

CHAPTER 11

Intelligence—How Would

a Fool Do It?

HUMAN DIVERSITY

Imagine being asked to sort some objects into categories. Wouldn’t

it be smart to separate the clothes, containers, implements, and

foods into separate piles? Not necessarily. When members of the

Kpelle culture in Liberia were asked to sort objects, they grouped

them together by function. For example, a potato (food) would

be placed together with a knife (implement). When the Kpelle

were asked why they grouped the objects this way, they often said

that’s how a wise man would do it. The researchers ﬁ nally asked

the Kpelle, “How would a fool do it?” Only then did the Kpelle sort

the objects into the nice, neat categories we Westerners prefer.

This anecdote, related by cultural psychologist Patricia Greenﬁ eld

(1997), raises serious questions about the limits of intelligence

testing. For example, the Cree people of Northern Canada value

visual skills needed to ﬁ nd food on the frozen tundra (Darou,

1992). The Puluwat people in the South Paciﬁ c prize oceangoing

navigation skills necessary to get from island to island (Sternberg,

2004). And so it goes, from culture to culture. Each culture teaches

its children the kinds of “intelligence” valued in that culture—how

the wise man would do it, not a fool (Correa-Chávez, Rogoff, &

Arauz, 2005). In view of such differences, psychologists have tried

to create “culture-fair” intelligence tests. Some have even stressed

the need to rethink the concept of intelligence itself. We’ll discuss

both of these ideas in this chapter’s Psychology in Action section.

“I knew my bag was going to be in the last place I looked, so I

looked there ﬁ rst.” What is silly or impossible about that?

Suppose that you are going east, then turn right, then turn right

again, then turn left. In what direction are you facing now?

Other items ask people to ﬁ ll in the missing shape in a group of

shapes, and to tell a story that explains what’s going on in a series

of pictures.

Working Memory

This part of the SB5 measures the ability to use short-term mem-

ory. Some typical memory tasks include:

Knowledge

This factor assesses the person’s knowledge about a wide range of

topics.

Correctly remember the order of colored beads on a stick.

After hearing several sentences, name the last word from each

sentence.

Repeat a series of digits (forward or backward) after hearing

them once.

After seeing several objects, point to them in the same order as

they were presented.

Why is yeast added to bread dough?

What does cryptic mean?

What is silly or impossible about this picture? (For example, a

bicycle has square wheels.)

If you were to take the SB5, it would yield a score for general

intelligence, verbal intelligence, nonverbal intelligence, and each

of the ﬁ ve cognitive factors (Bain & Allin, 2005; Roid, 2003). For

another perspective on the kinds of tasks used in the SB5, see

“Intelligence—How Would a Fool Do It?”

Quantitative Reasoning

Test items for this factor measure a person’s ability to solve prob-

lems involving numbers. Here are some samples:

If I have six marbles and you give me another one, how many

marbles will I have?

Given the numbers 3, 6, 9, 12, what number would come

next?

If a shirt is being sold for 50 percent of the normal price, and

the price tag is $60, what is the cost of the shirt?

Intelligence Quotients

Imagine that a child named Yuan can answer questions that an

average 7-year-old can answer. How smart is she? Actually, we

can’t say yet, because we don’t know how old Yuan is. If she is 10,

she’s not very smart. If she’s 5, she is very bright. Thus, to estimate

a child’s intelligence we need to know both her chronological

age (age in years) and her mental age (average intellectual perfor-

mance).

Mental age is based on the level of age-ranked questions a per-

son can answer. For example, at ages 8 or 9, very few children can

deﬁ ne the word connection. At age 10, 10 percent can. At age 13,

60 percent can. Thus, a 13-year-old of average ability can deﬁ ne

Visual-Spatial Processing

People who have visual-spatial skills are good at putting picture

puzzles together and copying geometric shapes (such as triangles,

rectangles, and circles). Other questions ask test takers to repro-

duce patterns of blocks and choose pictures that show how a piece

of paper would look if it were folded or cut. Verbal questions can

also require visual-spatial abilities:

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