History of IQ

The concept of Intelligence Quotient (IQ) has evolved over more than a century, shaped by the work of psychologists, educators, and researchers worldwide. IQ was originally developed to measure intellectual potential and problem-solving ability, but over the years it has also become a cultural and scientific touchpoint for discussions about human intelligence.

Early Foundations (19th Century)

The roots of IQ testing trace back to the late 1800s, when early psychologists like Francis Galton explored the measurement of human abilities. Galton believed intelligence could be quantified through sensory perception tests, but his methods were limited and lacked standardized scoring.

Birth of the First IQ Test (1905)

In 1905, French psychologist Alfred Binet, alongside his colleague Théodore Simon, created the first practical intelligence test. Commissioned by the French Ministry of Education, the Binet-Simon Scale was designed to identify students who needed special educational support. This marked the first time intelligence was systematically tested.

Stern and the IQ Formula (1912)

In 1912, German psychologist William Stern introduced the term “Intelligence Quotient” and proposed a formula: IQ = (Mental Age / Chronological Age) × 100. This method provided a numerical value for intelligence, which became the standard for decades.

American Adaptation and the Stanford-Binet Test (1916)

Lewis Terman of Stanford University revised Binet’s work to create the Stanford-Binet Intelligence Scale. This version was standardized for the U.S. population and is still in use today in updated forms.

IQ Testing in the Military (World War I & II)

During World War I, the U.S. Army introduced the Army Alpha and Army Beta tests to assess recruits’ abilities. This was the first large-scale use of intelligence testing, influencing military and educational systems for years.

Modern Developments

Today, IQ tests have evolved into diverse formats, including the Wechsler Adult Intelligence Scale (WAIS) and computer-based adaptive tests. They assess various cognitive domains, such as reasoning, memory, processing speed, and problem-solving skills. Modern psychologists also emphasize that IQ is just one measure of intelligence, and other factors like emotional intelligence, creativity, and practical skills are equally important.