Psychology Chapter on Intelligence Testing

Intelligence Definition

• David Wechsler defined intelligence as the overall ability to think rationally, act purposefully, and effectively interact with the environment.

Development of Intelligence Tests

• Alfred Binet, with Theodore Simon, developed procedures to identify students needing extra help.
• They created tests measuring various mental abilities, focusing on basic skills like memory, attention, and understanding similarities/differences.

Mental Age

• Mental age measures an individual's intellectual level by comparing their abilities to the average abilities of a particular age group.

IQ Scores and the Stanford-Binet Scale

• Lewis Terman adapted Binet's tests in the US, creating the Stanford-Binet intelligence scale.
• Scores are expressed as an IQ.
• IQ is a global measure evaluating an individual's performance relative to others in the same group.

High IQ and Success

• Terman's research on gifted children (IQ above 140) showed a correlation with social adjustment and physical health.
• However, high intelligence is not a guarantee of success in all aspects of life.
• High IQ does predict academic success, but success beyond school is influenced by other factors.

Wechsler's Contributions

• David Wechsler emphasized the multifaceted nature of intelligence.
• He recognized personality, motivation, and cultural factors as variables affecting IQ scores.
• He designed the Wechsler Intelligence Scale specifically for adults.
• The scale features subtests assessing different intellectual skills resulting in overall verbal and performance scores.

Wechsler Intelligence Scale (Verbal Score)

• The verbal score assesses vocabulary, comprehension, knowledge of general information, and other verbal tasks.

Wechsler Intelligence Scale (Performance Score)

• The performance score evaluates skills like identifying missing parts in incomplete pictures, arranging pictures to tell a story, and arranging blocks to match patterns.

Wechsler Intelligence Scale for Children

• The WISC-III and subsequent revisions (WISC-IV) are designed to assess intelligence in children aged 6 to 16.

Principles of Intelligence Test Construction

• Standardized tests, applying consistent procedures and norms to a large representative group.
• Reliable tests producing similar results across multiple administrations under identical conditions.
• Valid tests accurately measuring what they are designed to measure.

Standardization in Intelligence Testing

• Standardization involves administering a test to a large, representative sample under consistent conditions.
• This procedure establishes norms against which individual scores are compared and interpreted.
• IQ tests typically follow a normal distribution (bell curve).

The Normal Curve

• A bell-shaped distribution of individual differences in a normal population, where most scores cluster around the average.

Reliability and Validity

• Reliability refers to a test's consistency in producing similar results under the same conditions.
• Validity refers to a test's accuracy in measuring what it is intended to assess.

Nature of Intelligence

• Psychologists disagree on the basic nature of intelligence; some believe it is a single general ability, while others see it as a combination of skills, talents, and aptitude.

Intelligence Theories

• Charles Spearman proposed "g" factor (general intelligence) influencing overall mental ability.
• Louis Thurstone argued for multiple primary mental abilities as distinct elements of intelligence.
• Howard Gardner proposed multiple intelligences encompassing diverse skills and talents.
• Robert Sternberg identified analytic intelligence, creative intelligence, and practical intelligence as vital aspects.

Genetics and Environment in Intelligence

• Both genetics and environmental factors play a role in developing intelligence.
• Twin studies reveal significant correlations in IQ scores among identical twins raised together, slightly reduced correlations for identical twins raised separately.