7.5 Measures of Intelligence — When a Test Score Decides Life or Death | Psychology 2e

• Understand how IQ scores have been used in high-stakes legal decisions.
• Learn about the pioneers and original purpose of intelligence testing.
• Recognize the cultural and subjective biases present in early intelligence tests.
• Differentiate between standardization and norming in intelligence testing.
• Understand David Wexler's contribution to intelligence testing and his broader definition.
• Explain how IQ scores are distributed on a bell curve with a mean of 100.
• Learn about the Flynn effect and its environmental explanations for rising IQ scores.
• Identify the criteria for diagnosing intellectual disability, including IQ and adaptive functioning.
• Understand the shift from "mental retardation" to "intellectual disability" and its complexities.
• Challenge common stereotypes about gifted individuals with evidence from longitudinal studies.
• See how IQ tests uncover hidden educational needs beyond behavioral observations.
• Understand the historical weaponization of IQ test data in the American eugenics movement.
• Explore the landmark Supreme Court case Atkins v. Virginia regarding IQ and capital punishment.
• Examine how the legal system grapples with rigid IQ score cutoffs in capital punishment cases.
• Reflect on the ongoing efforts to refine IQ testing for accuracy, equity, and cultural fairness.
• Up next in “Psychology 2e — Full Course (OpenStax) | Intro Psychology Lectures”7.6 The Source of Intelligence — Nature, Nurture, and the Limits of IQ | Psychology 2e

This lesson explores how intelligence testing evolved from Alfred Binet's simple tool for identifying struggling French schoolchildren into a high-stakes instrument used in landmark U.S. Supreme Court cases. We walk through the mechanics of IQ scoring — standardization, norming, the bell curve, and standard deviations — before examining what happens at both extremes of the distribution. Along the way, we confront the Flynn Effect, the clinical definition of intellectual disability, and the deeply troubling history of IQ's misuse in the eugenics movement and capital punishment law. In this video: • From Binet to Wechsler: how intelligence testing developed from subjective visual tasks to the multi-index WISC-V • Standardization vs. norming — why both are essential for a meaningful IQ score • The bell curve explained: why 68% of people score between 85 and 115, with one standard deviation equal to 15 points • The Flynn Effect: rising IQ scores across generations and why James Flynn argued it reflects environmental change, not raw brainpower • Intellectual disability subtypes (mild, moderate, severe, profound) and how the DSM-5 shifted clinical terminology away from 'mental retardation' • The case of Candace: how an IQ score of 68 reframed a teenager's disruptive behavior as an unmet educational need • Atkins v. Virginia and Hall v. Florida: landmark Supreme Court rulings on IQ scores, intellectual disability, and the Eighth Amendment #OpenStax #Psychology #IQTest #IntelligenceTesting #EducationalPsychology OpenStax Content adapted from "OpenStax Psychology 2e", by OpenStax licensed under CC BY 4.0. Content based on Web Version: Apr 23, 2026. Read the textbook online https://openstax.org/details/books/psychology-2e Music first girl talking to me. by ikkun (ex. Barradeen) | https://soundcloud.com/ikkunwastaken Royalty Free Music by https://www.free-stock-music.com Creative Commons / Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0) https://creativecommons.org/licenses/by-sa/3.0/deed.en_US