The dark history of IQ tests - Stefan C. Dombrowski

Overview

The video argues that IQ tests, while originally created for practical educational purposes, became entangled with flawed theories of “general intelligence” and were repeatedly repurposed to support discriminatory and harmful ideologies.

Origins and intent (France, 1905)

Psychologists Alfred Binet and Théodore Simon developed a test to identify children struggling in school and who needed individualized instruction. The results were combined into a single score intended to reflect performance relative to other children of the same age, producing the concept of IQ (scaled around an average score of 100).

Scientific ambiguity about “general intelligence”

The test’s early framework assumed that tasks such as verbal reasoning, working memory, and visual-spatial skills reflect an underlying “g factor” (general intelligence). However, the video stresses that there is no single agreed definition of general intelligence, creating room for researchers and policymakers to misuse test results to support prior beliefs.

Early misuse linked to eugenics (U.S., WWI)

The video highlights the first large-scale use in the United States during World War I, when the military used IQ testing to sort recruits and screen them for officer training. It links this era to eugenics—including claims that intelligence was fixed, inherited, and tied to race—which fueled pseudo-scientific racial hierarchies. The video also notes that many recruits were immigrants with limited education or English exposure, making the testing especially problematic.

Policy atrocities justified by low IQ

• Virginia (1924): Policies enabling forced sterilization of people labeled as having “low IQ” were upheld by the U.S. Supreme Court.
• Nazi Germany: The video claims the government authorized the murder of children based on low IQ.

Scientific challenges: environmental effects (Flynn Effect)

After major civil rights efforts and post-Holocaust critique, researchers gathered evidence suggesting that intelligence test scores can rise too quickly to be explained by genetics alone. The video points to the Flynn Effect—successive generations scoring higher on older tests—arguing that improvements in education, healthcare, and nutrition better explain the changes than evolutionary shifts over short time spans.

Medical and diagnostic limitations

Mid-20th century attempts to use IQ subtests for psychiatric conditions (e.g., schizophrenia, depression) were criticized because they relied partly on clinical judgment and did not provide clinically useful information when based on IQ subcomponents. The video notes that IQ tests are no longer used for psychiatric diagnosis.

Ongoing problematic practice (learning disabilities)

While the video suggests psychiatric diagnosis via IQ has largely been abandoned, it argues that using subtest scores to diagnose learning disabilities still occurs despite expert advice against it.

What IQ tests are good for—and what they should not be used for

The video concludes that IQ tests can validly measure certain reasoning and problem-solving skills and are used for legitimate purposes, such as identifying intellectual disability and supporting educational and care planning.

However, it argues that IQ results have often been misused to unjustly claim broader human worth or “potential,” and that contemporary research increasingly rejects reducing people to a single numerical category.

Presenters/Contributors

• Stefan C. Dombrowski
• Alfred Binet
• Théodore Simon