I Took an IQ Test to Find Out What it Actually Measures

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Published 2023-08-03
IQ is supposed to measure intelligence, but does it? Head to brilliant.org/veritasium to start your free 30-day trial, and the first 200 people get 20% off an annual premium subscription.

If you’re looking for a molecular modeling kit, try Snatoms – a kit I invented where the atoms snap together magnetically – ve42.co/SnatomsV

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A huge thank you to Emeritus Professor Cecil R. Reynolds and Dr. Stuart J. Ritchie for their expertise and time.

Also a massive thank you to Prof. Steven Piantadosi and Prof. Alan S. Kaufman for helping us understand this complicated topic. As well as to Jay Zagrosky from Boston University's Questrom School of Business for providing data from his study.

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References:
Kaufman, A. S. (2009). IQ testing 101. Springer Publishing Company.

Reynolds, C. R., & Livingston, R. A. (2021). Mastering modern psychological testing. Springer International Publishing.

Ritchie, S. (2015). Intelligence: All that matters. John Murray.

Spearman, C. (1961). " General Intelligence" Objectively Determined and Measured. - ve42.co/Spearman1904

Binet, A., & Simon, T. (1907). Le développement de l'intelligence chez les enfants. L'Année psychologique, 14(1), 1-94.. - ve42.co/Binet1907

Intelligence Quotient, Wikipedia - ve42.co/IQWiki

Radiolab Presents: G. - ve42.co/RadioLabG

McDaniel, M. A. (2005). Big-brained people are smarter: A meta-analysis of the relationship between in vivo brain volume and intelligence. Intelligence, 33(4), 337-346. - ve42.co/McDaniel2005

Deary, I. J., Strand, S., Smith, P., & Fernandes, C. (2007). Intelligence and educational achievement. Intelligence, 35(1), 13-21. - ve42.co/Deary2007

Lozano-Blasco, R., Quílez-Robres, A., Usán, P., Salavera, C., & Casanovas-López, R. (2022). Types of Intelligence and Academic Performance: A Systematic Review and Meta-Analysis. Journal of Intelligence, 10(4), 123. - ve42.co/Blasco2022

Kuncel, N. R., & Hezlett, S. A. (2010). Fact and fiction in cognitive ability testing for admissions and hiring decisions. Current Directions in Psychological Science, 19(6), 339-345. - ve42.co/Kuncel2010

Laurence, J. H., & Ramsberger, P. F. (1991). Low-aptitude men in the military: Who profits, who pays?. Praeger Publishers. - ve42.co/Laurence1991

Gregory, H. (2015). McNamara's Folly: The Use of Low-IQ Troops in the Vietnam War; Plus the Induction of Unfit Men, Criminals, and Misfits. Infinity Publishing.

Gottfredson, L. S., & Deary, I. J. (2004). Intelligence predicts health and longevity, but why?. Current Directions in Psychological Science, 13(1), 1-4. - ve42.co/Gottfredson2004

Sanchez-Izquierdo, M., Fernandez-Ballesteros, R., Valeriano-Lorenzo, E. L., & Botella, J. (2023). Intelligence and life expectancy in late adulthood: A meta-analysis. Intelligence, 98, 101738. - ve42.co/Izquierdo2023

Zagorsky, J. L. (2007). Do you have to be smart to be rich? The impact of IQ on wealth, income and financial distress. Intelligence, 35(5), 489-501. - ve42.co/Zagorsky2007

Strenze, T. (2007). Intelligence and socioeconomic success: A meta-analytic review of longitudinal research. Intelligence, 35(5), 401-426. - ve42.co/Strenze2007

Deary, I. J., Pattie, A., & Starr, J. M. (2013). The stability of intelligence from age 11 to age 90 years: the Lothian birth cohort of 1921. Psychological science, 24(12), 2361-2368. - ve42.co/Deary2013

Flynn, J. R. (1987). Massive IQ gains in 14 nations: What IQ tests really measure. Psychological bulletin, 101(2), 171. - ve42.co/Flynn1987

Why our IQ levels are higher than our grandparents' | James Flynn, TED via YouTube -    • Why our IQ levels are higher than our...  

Duckworth, A. L., Quinn, P. D., Lynam, D. R., Loeber, R., & Stouthamer-Loeber, M. (2011). Role of test motivation in intelligence testing. Proceedings of the National Academy of Sciences, 108(19), 7716-7720. - ve42.co/Duckworth2011

Kulik, J. A., Bangert-Drowns, R. L., & Kulik, C. L. C. (1984). Effectiveness of coaching for aptitude tests. Psychological Bulletin, 95(2), 179. - ve42.co/Kulik1984

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Written by Derek Muller, Casper Mebius, & Petr Lebedev
Edited by Trenton Oliver
Filmed by Derek Muller, Han Evans, & Raquel Nuno
Animation by Fabio Albertelli & Ivy Tello
Additional video/photos supplied by Getty Images & Pond5
Music from Epidemic Sound
Produced by Derek Muller, Casper Mebius, & Han Evans

All Comments (21)
  • @mahirnagersheth
    I just took an IQ test and I am SO happy... Thank God it came back negative!
  • @tipsbunker4431
    When I was 8 years old my primary school teacher was convinced that I was gifted because I was always the first to finish a test and because I often seemed to get bored in class. One day I was taken out of class to take an IQ test for this reason. I have no memories of the test itself and no one ever told ma what the conclusion was. Around the age of 15 it also became clear that I had ADHD, despite this I was still holding up in school and I started taking medication. I am now 19 years old and a few months ago my parents told me that I had scored below average on this IQ test in primary school. The primary school psychologist (that had tested me) had told my parents that I would certainly not be able to go to university. My interest in science grew as I got older and when I asked my math teacher last year if I would be capable of studying engineering he said I definitely was. I have now completed my first year at the university. I am convinced that such IQ tests do not tell the full story at all. I had concentration problems and when I was 8 in primary school I had no idea what kind of test I was even taking. Don't let some number distract you from your goals!
  • @gronodon
    Here’s the thing: I used to be a middle school music teacher and went through all the special education and teaching strategy classes. What they don’t tell you is that a student’s IQ generally predicts their success in a traditional classroom setting, and is honestly a pretty poor judgment of individual intelligence outside of that very specific environment. When I was still an observing teacher prior to student teaching, I was in a music classroom doing recorders and a non-verbal autistic student was participating. As soon as they started their ear training exercises, he was the only kid that got every note right in less than a second and would patiently wait for the class to catch up to him. He had perfect pitch and knew exactly what he was doing, but due to his communication skills he struggled in classrooms that were simply a whiteboard and a lecture. When you gave him a recorder in an open classroom though? He became an extremely gifted young musician who was having a ton of fun and learning a lot!
  • @aronlinde1723
    The best way i heard IQ described is its like a combination of the acceleration of a car and its top speed. You can go a very distance from your starting point with a fast car that either accelerates quickly or has a high top speed but what really matters is the direction the car is going It doesnt matter how fast you are going if you are pointing the wrong direction.
  • I took an IQ test once that had a time limit and there was a clock in the room. I don't like time pressure so I panicked and ended up with a not too bad but still very depressing score. They made me take another test and told me it wasn't timed, I did way better, was proud of myself. They actually lied to me, it was timed, but by not telling me I just got a way better score and still finished in time. So many factors as to why someone would get a bad or good result in a test.
  • @realDonaldMcElvy
    I had an IQ of 123 when I was a teenager. I call it the Henry Ford Intelligence Test, because it only measures you like a factory worker.
  • @ChumblesMumbles
    That bit on motivation, training, test strategy, and anxiety hit the nail right on the head. It can be a very significant impact if all of those are in your favor or if they're working against you. I've been a good SAT-style (multiple choice, timed, reading/math/logic) tests ever since my elementary school started doing state level testing for school districts once a year way back when I was a kid. For me it was just a fun challenge and by the time I ran into standardized tests that caused other people to stress (PSAT, SAT, ACT, LSAT, multi-state bar exam) and actually mattered for some purposes, the "test" part of it was a walk in the park for me, and my only weaknesses were any actual knowledge gaps or making mistakes. Meanwhile I know folks who got immobilized by anxiety or just weren't used to the format had problems with the form of the test even if they had the knowledge down as well or better than me.
  • @selador11
    "Much more important is how you interact with and help those around you". The most brilliant statement in the entire video!!!
  • @seijirou302
    I was born in '81. I still remember in my kindergarten class there was a poster on the wall that read "It's not your IQ, it's your I WILL". That has stuck with me as demonstrably true my entire life.
  • @cupostuff9929
    It's actually really interesting that the IQ test has a baseline relative to the average of all scores, which means it measures your intelligence relative to others & not some fixed constant.
  • @justinlynch6691
    Man you knocked this out of the park. You really gave this its fair shake. I wish the public discourse covered subjects this thoroughly. You continue to raise the bar.
  • @FlemmingErnst
    This video contains sooo much more, interesting stats and scary history events. Thanks Veritasium.
  • @tieroberson
    Back in high school, I took several iq tests and would always score somewhere around the 132 range, so naturally I was walking around like the big brain on campus. Then I grew up and realized I'm dumb as hell, but just a really good test-taker.
  • @BryanBagehi
    My father was a psychologist. Growing up, he regularly administered various IQ tests on me. I became quite competent at standardized testing. To this day, I discount the value of these tests as I know I effectively cheated on them throughout the rest of my life. I learned test taking strategies and practiced the common types of questions so I am able to identify patterns of questions/answers favored in each test, which positively impacted my results compared to many others who did not have this experience.
  • Your point on child nutrition/education is so important. Ive seen so many altright people on the internet make racist comments based on IQ difference for populations when in fact it just shows that those populations are not having their basic needs met properly.
  • @zq5127
    I took an IQ test (as an adult) as part of ADHD testing. I’ve always been very into school, I’m in a master’s program right now, absolutely love learning, reading, writing, research, etc. I love learning random histories, facts, words, concepts, etc. Yet I was taken aback by some of the questions! One was “who wrote Alice in Wonderland?” How the hell does that show my intelligence? It’s so clearly eurocentric, even US-centric (at least the version I took… so much for “objectivity”). There are so many brilliant people who might’ve never had an experience where they could name the author of a book, or even never focused their attention on random facts like that, who would get those questions wrong, thereby reducing their score (I admit I don’t know a lot about how the tests are scored and normalized). But, clearly, it goes to show these tests can be arbitrary and designed for certain populations. They don’t predict what people can really do and how they think.
  • @smogy001
    Cecil: you're smarter than 98.8% of the population Derek: wow😒 Cecil: hopefully you're not disappointed Derek: *visibility disappointed*😕
  • @zorphorias1523
    Given how most schools are run, I feel like using IQ tests to indicate school success is a lot like saying "If you're good at taking tests, we can determine that you are good at taking tests."
  • @joliver81
    I remember at age 3 I used to completely disassemble my older sisters full size bike, after seeing my dad use his tools, mom caught me and said “ you put that back together right this second”, made me feel as though it was wrong as opposed to encouraging my curiosity. Think we all have great potential if nurtured properly.