Lecture Notes: Intelligence

Overview

• Introduction to the chapter on intelligence.
• Learning Objectives:
  • Identify and describe common measures of intelligence.
  • Understand forms of validity and reliability in IQ testing.
  • Explore genetic and environmental influences on intelligence.
  • Describe animal cognition.
• Chapter Outline:
  • History of intelligence testing.
  • Theories of intelligence.
  • Factors influencing intelligence.
  • Animal cognition.

Defining Intelligence

• Western view: Intelligence as mental skills aiding in school and work.
• Broader view: Ability to adapt to environmental demands.
• Intelligence as a socially constructed concept (e.g., motivation, anxiety).
• Agreed-upon definition: Ability to acquire knowledge, think, reason, and adapt.

History of Intelligence Testing

• Early Testing (2000 BC): Chinese civil service used IQ tests for job screening.
• Francis Galton (1860s):
  • Cousin of Darwin; influenced by Darwin's theories.
  • Studied genius through family trees; believed intelligence was hereditary.
  • Dismissed environment's role; focused on biological measures (e.g., head size).
• Alfred Binet and Theodore Simon:
  • Developed the first psychological test for school children in France.
  • Aimed to identify children needing specialized learning.
  • Proposed mental age concept: comparing test scores with age-appropriate scores.
• Wilhelm Stern:
  • Expanded Binet's concept to create the Intelligence Quotient (IQ).
  • Calculated IQ as (Mental Age / Chronological Age) x 100.
• Lewis Terman:
  • Modified Binet's test; created the Stanford-Binet Scale, widely used today.
• David Wexler:
  • Developed Wechsler Adult Intelligence Scale (WAIS) and Wechsler Intelligence Scale for Children (WISC).

Theories of Intelligence

• Psychometric Approach: Mapping intelligence structure through standardized tests.
• Types of Tests:
  • Achievement tests: current knowledge and skills.
  • Aptitude tests: predict future learning ability.
• Charles Spearman:
  • Proposed the "G factor" or general intelligence.
  • High correlation between different academic performance areas.
• L.L. Thurston:
  • Argued for seven distinct primary mental abilities.
• Cattell and Horn:
  • Proposed fluid intelligence (problem-solving) and crystallized intelligence (knowledge application).
• John B. Carroll:
  • Developed the three stratum model of intelligence: general, broad, and narrow abilities.
• Howard Gardner:
  • Proposed theory of multiple intelligences (e.g., linguistic, logical-mathematical).
• Robert Sternberg:
  • Developed triarchic theory of intelligence: analytical, practical, and creative intelligence.
• Emotional Intelligence:
  • Mayer and Salovey's components: perceiving, using, understanding, and managing emotions.

Studying Intelligence: Nature vs. Nurture

• Flynn Effect: Increase in IQ scores over time (28 points since 1910 in the US).
• Possible explanations:
  • Better nutrition, environmental complexity, and technological advances.
• Challenges in measuring intelligence across different cultures.
• Reliability and Validity:
  • Reliability: consistency of measurement (test-retest, internal consistency, inter-judge).
  • Validity: accuracy of what the test measures (construct, content, criterion-related).

Genetic and Environmental Influences on Intelligence

• Approximately 50-66% of IQ variation attributed to genetics.
• Environmental factors can account for 30-50% of IQ variation.
• Higher IQ in children moved from deprived to enriched environments.
• Genetic factors include heritability and epigenetics.
• Examples of environmental influences: family, socioeconomic status, education.

Group Differences in Intelligence

• Racial differences in IQ scores are often discussed.
• Historical figures like J. Philip Rushton proposed racial hierarchies in intelligence.
• Current understanding emphasizes environmental factors rather than genetic determinism.
• Intelligence is measured on a spectrum, with gifted individuals scoring above 130 IQ.
• Intellectual Disability: 3-5% of the population classified, with varying levels based on IQ.

Animal Cognition

• Challenges in measuring intelligence in animals; focus on cognition.
• Social intelligence hypothesis: intelligence evolves in complex social environments.
• Non-social species (e.g., octopus, echidna) also demonstrate high cognitive abilities.
• Importance of avoiding anthropomorphism in studying animal intelligence.