Lecture Notes: Intelligence and IQ Testing

Introduction

• Test Review: Multiple choice grades are posted, written questions to be graded soon.
• Chapter Focus: Starting on intelligence (Chapter 10).
• Recommendations: For those who didn’t take 104, review behavior genetics (from 104 or lecture notes) for understanding heritability of IQ.
• Key Terms Added: Ratio IQ and deviation IQ.

Defining Intelligence

• Controversy: Intelligence is a long-debated term in psychology, hard to define.
• Two Questions:
  1. What do we mean by the term in ordinary language?
  2. What should a scientific term mean?
• Wittgenstein’s Perspective: Meaning is found in customary use.
• Scientific Definition: More precise and useful; similar to temperature in thermodynamics.
• Psychological Definitions: Intelligence often defined as cognitive abilities including:
  • Ability to acquire knowledge.
  • Ability to reason effectively.
  • Adaptive interaction with the environment.

Historical Perspectives

• Francis Galton:
  • Influenced by Darwin, emphasized genetics in intelligence.
  • Coined "nature vs. nurture".
  • Pioneer of eugenics (controversial history).
• Alfred Binet:
  • Developed early intelligence tests to identify children needing educational support.
  • Introduced the idea of "mental age".

The Concept of IQ

• IQ (Intelligence Quotient):
  • Ratio IQ: Mental Age divided by Chronological Age x 100.
  • Deviation IQ: Takes into account standard deviations from the mean.
• Stanford-Binet Test: Early popular IQ test for children.

Factor Analysis and the 'G Factor'

• Factor Analysis: Technique to find correlations between cognitive tasks.
• Charles Spearman:
  • Discovered general intelligence (G Factor).
  • G explains much of the variation across different cognitive tasks.
• S Factors: Specific abilities within general intelligence.
• G and Brain Size: Correlates at 0.6 with brain size.

Models of Intelligence

• Thurstone’s Seven Sub-Abilities: Space, verbal comprehension, word fluency, number facility, perceptual speed, memory, reasoning.
• Crystallized vs. Fluid Intelligence:
  • Crystallized: Knowledge accumulation.
  • Fluid: Problem-solving ability.

Theories of Multiple Intelligences

• Sternberg’s Triarchic Theory:
  • Analytical, practical, and creative intelligence.
• Gardner’s Theory:
  • Eight types of intelligence: Linguistic, logical-mathematical, spatial, musical, bodily-kinesthetic, interpersonal, intrapersonal, and naturalist.

Emotional Intelligence

• Components: Important part of social interaction, includes perceiving emotions.
• Gender Differences: Women tend to perform better in emotional perception tests.

Modern IQ Testing

• Wechsler Adult Intelligence Scale (WAIS)
  • Composed of verbal comprehension, working memory, perceptual reasoning, and processing speed.
• Test Reliability
  • High test-retest reliability.
  • Consistent scoring across different examiners.

Reliability and Validity of IQ Tests

• Reliability: Consistency of the test scores over time and across different raters.
• Validity: To be discussed in the next class.