Overview
This lecture covers the development, history, scoring, and uses of intelligence (IQ) tests, including their controversies and implications in education and society.
Development and History of Intelligence Testing
- IQ (intelligence quotient) is a score from tests designed to measure intelligence.
- Sir Francis Galton developed the first broad intelligence test in the late 1800s.
- Alfred Binet created an intelligence test for French children to identify school difficulties.
- Louis Terman standardized and normed Binet’s test in the U.S., creating the Stanford-Binet Intelligence Scale.
- David Wechsler developed U.S. IQ tests including WAIS, WISC, and WPPSI, measuring multiple cognitive abilities and recalibrated regularly.
Scoring and Interpretation of IQ Tests
- Standardization ensures tests are administered and scored consistently.
- Norming compares test results to a large, representative sample to establish reference scores (norms).
- The bell curve (normal distribution) is used to interpret IQ scores, with a mean of 100 and standard deviation of 15.
- 68% of people have IQs between 85 and 115; scores 130+ are considered gifted; scores below 70 may indicate intellectual disability.
Flynn Effect and Validity of IQ Tests
- The Flynn effect is the observed rise in average IQ scores over generations.
- Increased scores do not necessarily mean increased intelligence.
- Debate continues over which skills should be measured and how valid IQ tests are for assessing overall intelligence.
Intellectual Disability and Giftedness
- Intellectual disability is diagnosed with IQ ~70 or below, deficits in adaptive functioning, and onset before age 18.
- Intellectual disability subtypes: mild, moderate, severe, profound, varying by skills and independence.
- Giftedness is generally defined as an IQ of 130 or above; study shows gifted individuals are typically well-adjusted.
Societal and Legal Implications
- IQ scores have been controversially used in contexts like eugenics and the justice system.
- Supreme Court cases (Atkins v. Virginia, Hall v. Florida) addressed the use of IQ scores in death penalty eligibility for people with intellectual disabilities.
- The term "intellectual disability" has replaced "mental retardation" in clinical and legal settings due to stigma.
Uses and Benefits of IQ Testing
- IQ tests help identify children and adults in need of special educational or clinical support.
- Results are used in schools, courts, and for obtaining disability benefits.
- Testing methods and interpretation are continually updated for greater fairness and accuracy.
Key Terms & Definitions
- IQ (Intelligence Quotient) — Score from a test designed to measure intelligence.
- Standardization — Consistent administration and scoring of a test.
- Norming — Establishing reference scores by testing a large, representative sample.
- Bell Curve — Normal distribution graph showing the spread of a trait in a population.
- Flynn Effect — Generational increase in average IQ scores.
- Intellectual Disability — Significant cognitive and adaptive deficits with onset before age 18.
- Gifted — Having an IQ of 130 or above.
Action Items / Next Steps
- Review the five indices of the WISC-V.
- Reflect on the societal impact of changes in terminology regarding intellectual disabilities.
- Prepare to discuss or answer questions on the use and interpretation of IQ tests in legal and educational contexts.