Psychology Module 30 Review

What is an intelligence test, and what is the difference between achievement and aptitude tests?

An intelligence test is a method for assessing an individual's mental aptitudes and comparing them with others, using numerical scores. Aptitude tests measure the ability to learn, while achievement tests measure what we have already learned.

When and why were intelligence tests created, and how do today's tests differ from early intelligence tests?

In the late 1800s, Francis Galton, who believed that genius was inherited, attempted but failed to construct a simple intelligence test. Alfred Binet, who tended toward an environmental explanation of intelligence differences, started the modern intelligence-testing movement in France in 1904 when he developed questions to help predict children's future progress in the Paris school system. During the early twentieth century, Lewis Terman of Stanford University revised Binet's work for use in the United States. Terman believed intelligence was inherited, and he thought his Stanford-Binet could help guide people toward appropriate opportunities. From such tests, William Stern contributed the concept of the IQ (intelligence quotient). During this period, intelligence tests were sometimes used to "document" scientists' assumptions about the innate inferiority of certain ethnic and immigrant groups. The most widely used intelligence tests today are the Wechsler Adult Intelligence Scale (WAIS) and Wechsler's tests for children. These tests differ from their predecessors in the way they offer an overall intelligence score as well as scores for various verbal and performance areas.

What is a normal curve, and what does it mean to say that a test has been standardized and is reliable and valid?

The distribution of test scores often forms a normal (bell-shaped) curve around the central average score, with fewer and fewer scores at the extremes. Standardization establishes a basis for meaningful score comparisons by giving a test to a representative sample of future test-takers. Reliability is the extent to which a test yields consistent results (on two halves of the test, on alternative forms of the test, or when people are retested). Validity is the extent to which a test measures or predicts what it is supposed to. A test has content validity if it samples the pertinent behavior (as a driving test measures driving ability). It has predictive validity if it predicts a behavior it was designed to predict. (Aptitude tests have predictive ability if they can predict future achievements; their predictive power is best for the early school years.)

mental age

a measure of intelligence test performance devised by Binet; the chronological age that most typically corresponds to a given level of performance. Thus, a child who does as well as an average 8-year-old is said to have a mental age of 8.

intelligence test

a method for assessing an individual's mental aptitudes and comparing them with those of others, using numerical scores.

achievement test

a test designed to assess what a person has learned.

aptitude test

a test designed to predict a person's future performance; aptitude is the capacity to learn.

intelligence quotient (IQ)

defined originally as the ratio of mental age (ma) to chronological age (ca) multiplied by 100 (thus, IQ = ma/ca × 100). On contemporary intelligence tests, the average performance for a given age is assigned a score of 100.

standardization

defining uniform testing procedures and meaningful scores by comparison with the performance of a pretested group.

Wechsler Adult Intelligence Scale (WAIS)

the WAIS and its companion versions for children are the most widely used intelligence tests; contain verbal and performance (nonverbal) subtests.

normal curve

the bell-shaped curve that describes the distribution of many physical and psychological attributes. Most scores fall near the average, and fewer and fewer scores lie near the extremes.

validity

the extent to which a test measures or predicts what it is supposed to. (See also content validity and predictive validity.)

content validity

the extent to which a test samples the behavior that is of interest.

reliability

the extent to which a test yields consistent results, as assessed by the consistency of scores on two halves of the test, on alternative forms of the test, or on retesting.

predictive validity

the success with which a test predicts the behavior it is designed to predict; it is assessed by computing the correlation between test scores and the criterion behavior. (Also called criterion-related validity.)

Stanford-Binet

the widely used American revision (by Terman at Stanford University) of Binet's original intelligence test.