Psychology Chapter on Intelligence Testing

Intelligence Defined

• David Wechsler defined intelligence as the overall capacity 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 support.
• They created tests measuring various mental skills, focusing on fundamental abilities like memory, attention, and recognizing similarities/differences.

Mental Age

• Binet's work introduced the concept of mental age, which differs from a child's chronological age.
• Mental age is a measure of intelligence, expressing an individual's mental level based on the average abilities of their age group.

Stanford-Binet Intelligence Scale

• Lewis Terman adapted Binet's test, naming it the Stanford-Binet intelligence scale.
• Scores are expressed as an Intelligence Quotient (IQ).

Intelligence Quotient (IQ)

• IQ is a measure of overall intelligence, calculated by comparing an individual's score to the average score of others in the same group.

High IQ and Success

• Lewis Terman's longitudinal study of children with high IQs (above 140) showed they tended to be well-adjusted socially.
• These children also exhibited taller, stronger, and healthier features than average children.
• However, high intelligence doesn't guarantee success; other factors play a role in life achievements beyond school success.

Wechsler's Perspective

• David Wechsler (1896-1981) believed intelligence involved many mental skills.
• He also thought IQ scores could be affected by personality, motivation, and cultural variables.
• He developed the Wechsler Intelligence Scale for adults.

Wechsler Intelligence Scale

• Intended specifically for adults, rather than children.
• Includes 11 subtests covering various abilities.
• Subtest scores are gathered to create an overall verbal score, and performance score.

Wechsler Verbal Skills

• Vocabulary
• Comprehension
• Knowledge of general information
• Other verbal tasks

Wechsler Performance Skills

• Identifying missing components in incomplete pictures.
• Arranging pictures to tell stories.
• Arranging blocks to follow given patterns.

Wechsler Intelligence Scale for Children

• The Wechsler Intelligence Scale for Children (WISC-III) designed in 1991 measures intelligence in children from 6 to 16 years.
• The WISC-IV is the revised version of 2003.

Intelligence Test Principles

• Three essential elements of reliable tests:
  • Standardization : The test is given to a large, representative sample of people under uniform conditions to generate norms against which individual scores are interpreted. IQ test norms follow a normal curve or normal distribution.
  • Reliability: The ability of a test to give consistent results under the same conditions when administered repeatedly.
  • Validity: The ability of a test to measure what it is intended to measure.

The Normal Curve (Normal Distribution)

• The bell-shaped normal distribution illustrates how most scores cluster around average in a typical population.
• IQ scores generally follow a normal curve, indicating similar clusters among the scores in a population.

Nature of Intelligence

• Psychologists disagree on the essential nature of intelligence, including whether it's a single, general ability or if it incorporates talents, skills, and mental aptitude.

Theories of Intelligence

• Charles Spearman: Proposed "general intelligence" (g factor) underpinning overall mental ability.
• Louis Thurstone: Believed intelligence comprises several distinct, independent "primary mental abilities".
• Howard Gardner: Argued for "multiple intelligences", each relevant within different cultural settings.
• Robert Sternberg: Described analytic, creative, and practical intelligence.

Roles of Genetics and Environment

• Both genetics and the environment influence intelligence.
• Twin studies demonstrate a strong genetic influence, suggesting identical twins raised together have highly correlated IQ scores, and those raised apart have slightly less similar IQs.