Intelligence and Intelligence Tests

Chapter 9: Intelligence

Introduction to Intelligence

• Intelligence is challenging to define; traditional definitions involve concepts such as judgment, understanding, and rational thinking.
• There is no universally accepted definition of intelligence. Researchers aim to measure it to gain insights.

Spearman’s Psychometric Approach

• Spearman proposed a psychometric approach focusing on individual performance differences.
  • General Ability (g): Represents a common factor across different types of intelligence.
  • Specific Abilities (s): Special skills (e.g., musical, logical) that contribute to specific tasks.
• Intelligence comprises a combination of general ability and specific abilities.

Explanations for the g Factor

• The g factor is thought to underlie various intelligences, correlating with mental speed and working memory.
• Different intelligences may improve due to shared underlying factors or growth factors supporting multiple abilities.

Types of Intelligence

• Fluid Intelligence:
  • Related to reasoning and solving novel problems.
  • Peaks in early adulthood.
• Crystallized Intelligence:
  • Involves accumulated knowledge and skills used in specific contexts.
  • Peaks in middle age and remains stable.

IQ Tests

• Aptitude: Measures potential fluid intelligence.
• Achievement: Reflects crystallized intelligence.
• IQ tests attempt to forecast academic performance based on these abilities.
• Mental Age: Represents the average capability of children that corresponds to an individual’s score.

Major IQ Tests

• Stanford-Binet Test:
  • Provides overall IQ scores, including verbal and non-verbal sections.
  • Includes subscores for specific abilities.
• Wechsler Tests:
  • Produces a similar score distribution to the Stanford-Binet test.
  • Assesses various domains including verbal, performance, and processing speed.

Culture-Reduced Testing

• Progressive Matrices:
  • Measures abstract reasoning without linguistic bias.
  • Advantages: Fairer for non-native English speakers.
  • Disadvantage: Offers a single score without detailed strengths/weaknesses.

Individual Differences in IQ Scores

• Family Similarities: Correlation of IQ scores shows:
  • Identical twins: correlation of 0.85.
  • Siblings and twins demonstrate varying degrees of IQ resemblance.
• Adopted Children: IQ correlated with biological parents but influenced by shared environments.

Genetic Influences on IQ

• No single gene has a significant impact; intelligence results from many genes with minor contributions.
• Epigenetic influences (i.e., how genes are expressed) are critical in determining intelligence.

Environmental Influences

• Factors like physical health in childhood, education, nutrition, and cognitive stimulation are vital for intellectual development.

Intelligence and Brain Size

• Larger brain size correlates with higher intelligence; however, intelligence isn't solely reliant on size (e.g., gender differences, neuron count).

Evaluating Intelligence Tests: Validity and Reliability

• Standardization: Process of evaluating, administering, and interpreting test scores based on norms.
  • The mean IQ is typically set at 100, with a standard deviation of approximately 15-16.
• Reliability:
  • Consistency of test results over time.
• Validity: Measures how well the test assesses what it claims to measure through various methods.

The Flynn Effect

• Observed improvement in IQ test scores over generations, approximately 3 IQ points every decade.
  • Possible causes include improved education, better health, and increased cognitive stimulation.

Test Bias and Stereotype Threat

• Bias occurs when tests overstate or understate performance for particular groups.
• Stereotype Threat: The anxiety individuals feel about confirming negative stereotypes about their group, which can impair performance.
• Strategies to combat stereotype threat include awareness and writing interventions to reduce anxiety.

Conclusion and Key Concepts to Remember

• Understand and describe the nature of g and multiple intelligences.
• Distinction between fluid and crystallized intelligence.
• Evaluate common IQ tests like Stanford-Binet and Wechsler.
• Analyze hereditary vs. environmental impacts on intelligence.
• Discuss brain size's relationship with intelligence.
• Define and explain standardization, reliability, and validity in testing, alongside concepts of bias and stereotype threat.