Unit XI: Testing & Individual Differences

Module 61

Assessing Intelligence

Origins of Intelligence Testing 61-1

Alfred Binet

• Alfred Binet developed questions that would predict children’s future progress in the Paris school system.

• He hoped the test would be used to improve children’s education, but also worried that the test would be used to label children & limit their opportunities.

61-1

Lewis Terman & IQ

• In the US, Lewis Terman adapted Binet’s test for American school children and named the test the Stanford-Binet Test.

• Then William Stern introduced the following formula to derive a person’s Intelligence Quotient (IQ):

• Today, “IQ” is still used as

shorthand to represent an

intelligence test score – or a test taker’s performance

relative to the average performance of others the same age.

61-1

Achievement vs. Aptitude Tests 61-2

Achievement vs. Aptitude

• Achievement tests – measure what a person has learned

• Aptitude tests – predict a person’s future performance (aptitude = the capacity to learn)

61-2

Wechsler Adult Intelligence Scale

• Wechsler developed the Wechsler Adult Intelligence Scale (WAIS) and later the Wechsler Intelligence Scale for Children (WISC), an intelligence test for school-aged children.

• It is now the most widely used intelligence test.

61-2

WAIS

WAIS measures overall intelligence and 11 other aspects related to intelligence.

61-2

Standardization & the Normal Curve

61-3

Standardization

• Defining uniform testing procedures and meaningful scores by comparison with the performance of a pre-tested group

• The group member’s scores typically are distributed in a bell-shaped pattern that that forms the normal curve

61-3

Normal Curve 61-3

Reliability & Validity 61-4

Principles of Test Construction

For a psychological test to be acceptable it must be standardized, reliable, and valid.

• Reliability – the extent to which a test yields consistent results

• Validity – the extent to which a test measures or predicts what it is supposed to

• General aptitude tests are highly predictive from ages 6-12

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