Nov 24, 2025·History & Origins Of IQ Testing
When Was IQ Testing Invented?
When was the IQ test invented? In 1905, Alfred Binet & Théodore Simon created the first successful IQ test in France. Discover when IQ testing began!
IQ testing was invented in 1905 by French psychologist Alfred Binet and his colleague Theodore Simon. They created the first successful intelligence test in Paris to help identify children who needed additional educational support. This test became the foundation for all modern intelligence testing.
The Failed Attempts Before Binet
Sir Francis Galton (1822-1911) made the most notable early attempt to measure intelligence. In the 1880s, this English scientist set up a laboratory in London where he measured head circumference, reaction time, visual acuity, grip strength, and other basic physiological variables. He theorized these physical measurements would correlate with social class, which he viewed as a reflection of intelligence.
After years of data collection, Galton found that none of these variables were related to social class. With modern knowledge, we now know that some variables he measured do relate to intelligence (like reaction time), but his statistical methods weren't sophisticated enough to detect these relationships.
Binet and Simon's Breakthrough
Alfred Binet took a completely different approach. Rather than measuring physical traits and basic behaviors, he focused on complex tasks, specifically things that actually required thinking, reasoning, and problem-solving.
At the turn of the 20th century, France was debating how to educate children with special needs. Should they be placed in psychiatric facilities or given special classes within regular schools? Binet and Simon created their test as part of their advocacy for keeping these children in educational settings.
Their 1905 test consisted of 30 tasks arranged by difficulty, measuring abilities like attention, memory, and comprehension. Unlike Galton's physical measurements, performance on Binet and Simon’s test was related to real-world outcomes (in this case, performance in school). Improved versions followed in 1908 and 1911. Binet died in 1911 at age 54.
Binet's test was quickly translated into multiple languages and adapted worldwide. In the United States, Stanford University professor Lewis Terman saw enormous potential. In 1916, he published an expanded version called the Stanford-Binet Intelligence Test, covering a wider range of abilities and ages. It became wildly popular and a modern version remains in use today.
From Individual to Mass Testing
Until World War I, all intelligence tests were administered individually, one administrator testing one person at a time. This changed when the United States entered the war in 1917.
The U.S. Army needed to process millions of recruits and identify potential leaders. Individual testing was impractical at this scale. A committee of psychologists led by Robert Yerkes created the Army Alpha (for literate soldiers) and Army Beta (for men with limited literacy), which were the first tests administered to large groups simultaneously.
Over 2 million tests were given before the war ended. The tests proved successful, correlating with military rank, training success, and pre-war education and occupational prestige. Although they had minimal impact on the war's outcome, they demonstrated that mass testing was feasible. This opened the door for widespread testing in schools and employment settings.
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