Human Measurement of Intelligence Through the Ages

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Have you ever wondered how our ancestors measured intelligence? It’s a concept that has intrigued societies for millennia. From the examining of head bumps in ancient phrenology to the modern-day IQ testit seems people have always been curious about intellectual prowess. While phrenology erroneously assumed that the bumps on our skulls could reveal our mental faculties, today’s IQ tests use a variety of complex tasks to offer a peek into different people’s cognitive abilities. Yet, the journey from reading skull shapes to filling in multiple-choice questions says a lot about how our understanding of intelligence has evolved over the years. Who would have guessed those early, quirky theories would be the forerunners to the intricate assessments we see today?

Ancient Greeks and the Idea of Multiple Intelligences

The ancient Greeks had a nuanced understanding of intelligence. Unlike modern society, they did not have just one word to describe intelligence. Platoone of the most influential Greek philosophers, differentiated between two ways of using reason: discursive reason or dianoia and intuitive reason or nous. Discursive reason involves a step-by-step process of reasoning, often used in mathematical proofs and logic exercises. On the other hand, intuitive reason is a quick and direct form of reasoning, which Plato considered the highest form of human intelligence. He believed that intuition allowed for a direct contemplation of truth. These two faculties were seen as distinct ways of using reason, unique to human beings.

Close up image of Plato (left) from The "School of Athens" (Public Domain)

Close up image of Plato (left) from The “School of Athens” (Public Domain)

Phrenology and Reading the Shape of Your Skull

In the 19th century, phrenology gained popularity as a way to understand intelligence. Phrenologists believed that the shape and size of different areas of the skull corresponded to specific mental faculties.

1883 Phrenology diagram (Public Domain)

1883 Phrenology diagram (Public Domain)

By examining the bumps and contours of a person’s head, phrenologists claimed to be able to determine their intelligence and personality traits. However, phrenology has since been discredited as a pseudoscience, lacking empirical evidence to support its claims.

Alfred Binet’s IQ Test, A.K.A., The First Recognized IQ Test

In the early 20th century, French psychologist Alfred Binet developed the first recognized IQ test. At the time, the French government required all children to attend school and Binet was tasked with identifying students who might need extra help. Binet and his colleague Theodore Simon created a test that focused on areas not explicitly taught in the classroom, such as attention, memory and problem-solving skills. This test, known as the Binet-Simon Scale, became the foundation for measuring intelligence. It consisted of 30 questions and provided a score known as the intelligence quotient (IQ).

Reproduction of an item from the 1908 Binet-Simon intelligence scale, showing three pairs of pictures, about which the tested child was asked, "Which of these two faces is the prettier?" The drawings were reproduced in the article "A Practical Guide for Administering the Binet-Simon Scale for Measuring Intelligence" by J. W. Wallace Wallin in the March 1911 issue of the journal The Psychological Clinic (Public Domain)

Reproduction of an item from the 1908 Binet-Simon intelligence scale, showing three pairs of pictures, about which the tested child was asked, “Which of these two faces is the prettier?” The drawings were reproduced in the article “A Practical Guide for Administering the Binet-Simon Scale for Measuring Intelligence” by J. W. Wallace Wallin in the March 1911 issue of the journal The Psychological Clinic (Public Domain)

The Stanford-Binet Intelligence Scale

Stanford University psychologist Lewis Terman standardized Binet’s original test for use with American participants, resulting in the Stanford-Binet Intelligence Scale. Published in 1916, this test translated the French terms and ideas into English and introduced new terms. It provided a single IQ score to represent an individual’s intelligence. Despite undergoing revisions over the years, the Stanford-Binet test remains a widely used assessment tool today.

The Wechsler Intelligence Scales

American psychologist David Wechsler believed that intelligence involved different mental abilitiesleading him to develop the Wechsler Intelligence Scales. In 1955, he published the Wechsler Adult Intelligence Scale (WAIS), which aimed to overcome the limitations of the Stanford-Binet test. Wechsler also created two tests specifically for children: the Wechsler Intelligence Scale for Children (WISC) and the Wechsler Preschool and Primary Scale of Intelligence (WPPSI). These tests have undergone revisions and are still used today to assess intelligence in different age groups.

Wechsler Intelligence Scale for Children (Onderwijsgek at nl.wikipedia/CC BY-SA 3.0)

Wechsler Intelligence Scale for Children (Onderwijsgek at nl.wikipedia/CC BY-SA 3.0)

In conclusion, our understanding of intelligence has evolved over time. From the ancient Greeks’ recognition of multiple forms of reasoning to the development of IQ tests by psychologists like Alfred Binet and David Wechsler, we have made significant strides in deciphering the enigma of intelligence. While there is still much to learn, these historical milestones have paved the way for further exploration and understanding of human intelligence.

Top image: AI generated composite of time, scrolls and ancient ruins. Source: Bazoom

By Ron Sweeny

References

Hartman. D. 2009. Wechsler Adult Intelligence Scale IV (WAIS IV): Return of the Gold Standard. Applied Neuropsychology, 16(1). https://doi.org/10.1080/09084280802644466

Palanca-Castan, N., Tajadura, B., Cofréc, R. 2021. Towards an interdisciplinary framework about intelligence. National Library of Medicine, 7(2). https://doi.org/10.1016%2Fj.heliyon.2021.e06268

Parker Jones, O., Alfaro-Almagro, F., Jbadi, S. 2018. An empirical, 21st century evaluation of phrenology. National Library of Medicine, 106(26-35). https://doi.org/10.1016%2Fj.cortex.2018.04.011

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