Chapter 9 first explores the history of the evolution of intelligence measurement, current types of tests and how they differ, as well as the controversial, unethical policies stemming from the implementation of eugenics programs based on flawed intelligence testing. Chapter 9 also explores in depth the nature of IQ tests, their validity, links between IQ and poverty, genetics, and so on.
The book cites a definition of intelligence from the awesomely (perhaps fittingly) named psychologist, Edwin Boring: "Intelligence is whatever intelligence tests measure". Thank you, Edwin Boring, for clearing that up.
Our chapter 9 story starts in the late 1880s, Sir Francis Galton, a cousin of Charles Darwin, believed that intelligence was derived from the sharpness of our senses, i.e. hearing, vision, etc, and in having keener senses, those humans were more intelligent, and thus have superior reproductive success in line with Darwin's theory. Later research disproved this theory, on the basis of the weak correlation between keen senses and intelligence. I question this, because I'm sure my cat has much sharper senses than I do, but I don't see my cat writing this...
Later research explored the idea of intelligence as a multifaceted aspect of the mind. In 1905, two French scientists, Alfred Binet, and Théodore Simon created a new test at the behest of the French government, with the goal of creating a metric for 'higher mental processes'. The duos' tests measured abstract reasoning with objects, sentences, pictures, word knowledge. This approach, which encompassed several areas, would become the foundation for future research into intelligence metrics. This test was translated in 1908 by American psychologist Henry Goddard, and IQ testing exploded in popularity. IQ tests were misused to keep immigrants out of the US, as well as justify cruel mandatory sterilization of thousands of 'low-IQ' individuals within the US and around the world, as part of the wider eugenics movement.
In the 1920s, a psychologist named Charles Spearmen, noticed correlations between test results, and postulated that these correlations represented an underlying 'general intelligence, or 'g', a mental equivalent to horsepower, 'g' representing a form of mental energy. The more 'g', your brain is more efficient and capable than someone with less 'g'. Spearman also presented the notion that the brain might be stronger in certain areas, represented by a factor he called specific abilities, or 's'.
The nature of human intelligence was further distinguished by the definition of 'fluid intelligence' and 'crystalized intelligence', in the late 1930s, by several scientists. A game show like Jeopardy draws purely from crystallized intelligence, random trivia, facts, knowledge accumulated about the world, s-words, art history for 500, and so on. Fluid intelligence, however, refers to our ability to solve problems, for example how quickly one can learn how to drive stick or solve a Rubik's cube.
Fast-forward to the 80s, and we've got Howard Gardner with the theory of 'multiple intelligences', a much friendliest view of intelligence that's far more inclusive than something like 'g'. Rather than just having more brain-power, Howard Gardner proposes that people have strength in various areas and all of these areas are a form of intelligence. For example, one could say Sting possesses great musical intelligence, where as Van Gogh had great spatial intelligence, but poor intrapersonal intelligence.
Today, there are many tests in use, all attempting to correct for faults in earlier testing paradigms. I find it interesting that the 'Weschler Adult Intelligence Scale' test, psychologist David Weschler, was created by a man classified as 'feebleminded' by earlier IQ tests. Variants of this WAIS test are available for children. Another aim of more modern IQ tests is to avoid the cultural bias prevalent in earlier tests, to make it fair for people who might not have a strong grasp of the language or the culture of the testers.
- Adam Priest
Lilienfeld, S.O., Lynn, S.J., Namy, L., & Woolf, N. (2010). Psychology: From inquiry to understanding (2nd edition). Boston, MA: Pearson.