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Intelligence: A Very Short Introduction – Ian J. Dury

Summary: Ian Dury outlines the history of the study of intelligence, as well as the current scientific understanding of it. While intelligence is an abstract concept, its utility has been well established: it can be used to predict many things, such as career success and longevity, and can give us insights into how the brain works. Intelligence is heritable and fairly stable over the course of one's life.

Thoughts: I found this book to be quite interesting. Dury supports each of his main points by looking at several scientific studies, and I appreciated that all of these were either metastudies or robust studies with very large sample sizes. With fewer than 200 pages, it wasn't a huge investment of time. This was my first Very Short Introduction, and I expect it won't be my last!

(I took more notes than usual on this book, so it should come fairly close to a full summary.)

Dury, Ian J. 2020. Intelligence: A Very Short Introduction (2nd Edition). Oxford UP.

Chapter 1 - Is there one intelligence or many?

The Wechsler Adult Intelligence Scale IV

Carroll’s ‘Human Cognitive Abilities’ Survey

‘Intelligence’ beyond intelligence tests

Chapter 2 - What happens to intelligence as we grow older?

Salthouse’s Virginia Studies

Does intelligence ‘all go when it goes’?

The Scottish Mental Surveys of 1932 and 1947

Preventing some age-related cognitive decline

Chapter 3 - Are there sex differences in intelligence?

The Scottish Mental Survey 1932

The National Longitudinal Survey of Youth 1979

The Cognitive Abilities Test 3 sample

Chapter 4 - What are the contributions of environments and genes to intelligence differences?


10,000+ twins, from three continents


DNA from 300,000 people in fifty-seven studies

Chapter 5 - Are smarter people faster?

The West of Scotland Twenty-07 Study

The Lothian Birth Cohort 1936

Speed and other cognitive processes

Chapter 6 - What do more intelligent brains look like?

The Lothian Birth Cohort 1936

Brain volume and intelligence

Intelligence beyond brain structure

Chapter 7 - Does intelligence matter in the school and the workplace?

English National GCSE examination results

Job selection and job performance

Success in life beyond intelligence

Chapter 8 - Does intelligence matter for health and longer life?

The Scottish Mental Survey of 1947

Intelligence in youth and all-cause mortality

The National Longitudinal Survey of Youth 1979

Chapter 9 - Is intelligence increasing generation after generation?

The (James) Flynn Effect of rising IQ

Flynn’s ‘Massive IQ gains in 14 nations’

‘One century of global IQ gains’

Chapter 10 - Do psychologists agree about intelligence differences?

The Bell Curve

A working party on intelligence’s knowns and unknowns

The APA Task Force on conceptions of intelligence

The APA Task Force on intelligence tests and their correlates

The APA Task Force on genetic and environmental contributions to intelligence

The APA Task Force on group differences in intelligence

The APA Task Force’s conclusions

Summaries of intelligence research after the APA Task Force

Signing off, and encouragement to read more …

References and Further Reading

Defining intelligence, at last

“The American Psychological Association’s Task Force (Chapter 10) wrote that definitions come at the end of research rather than the start. I agree, and therefore I waited until here before offering one. Many people repeat Linda Gottfredson’s definition: ‘Intelligence is a very general mental capability that, among other things, involves the ability to reason, plan, solve problems, think abstractly, comprehend complex ideas, learn quickly and learn from experience. It is not merely book learning, a narrow academic skill, or test-taking smarts. Rather, it reflects a broader and deeper capability for comprehending our surroundings—“catching on”, “making sense” of things, or “figuring out” what to do.’”

Posted: Dec 10, 2020. Last updated: Dec 19, 2020.