Video summary

The Strangest Things that Correlate with IQ

Main summary

Key takeaways

Educational

Main ideas / lessons

  • What IQ is (definition): IQ is a standardized score intended to reflect general cognitive ability—the shared performance across many “intelligence tasks” (e.g., logic, math, spelling, vocabulary). It is about what these lab-measured tasks have in common.

  • IQ doesn’t predict everything important: IQ does not reliably predict outcomes like social success, morality, or happiness, and it may not align with traits people assume are linked to intelligence (e.g., diligence).

  • Some “strangest” correlations with IQ are about perception, upbringing, and health behaviors/environmental factors, not about obvious “smartness” stereotypes.

  • Useful correlations exist—especially around modifiable health and early-life factors, even though causality can be complex.

  • Skill growth does not require higher IQ: You can improve performance at almost any task through practice and feedback; high IQ helps only indirectly via baseline ability, not via training itself.

  • Beliefs and values correlate with IQ: Higher IQ is associated with patterns like less religiosity and more support for free speech for disliked viewpoints.

  • Happiness and “being a hard worker” are not strongly explained by IQ: Studies find no meaningful link between IQ and life satisfaction, and conscientiousness is weakly related or not related to IQ.

Correlations presented (with explanations)

1) “Pseudo-profound” language perception

  • Claim: Higher-IQ people tend to rate grand-sounding, unclear statements as less profound.
  • Proposed reason: They’re less likely to assume something is meaningful simply because they don’t immediately understand it.

2) Firstborn status

  • Claim: IQ is associated with being firstborn (difference is small, only a few IQ points).
  • Proposed reason: Parental investment theory—parents may spend more time/resources raising the first child.

3) Beliefs about solving societal problems

  • Claim: People who believe they can’t solve societal problems tend to have higher IQ on average.
  • Proposed reason: They may be more aware of how difficult those solutions are.
  • Correction/clarification: This is described as not simply the Dunning–Kruger effect as commonly misconstrued:
    • Dunning–Kruger: lower-skilled people overestimate their own ability, not that they think they’re inferior to higher-skilled people.

4) Glasses / nearsightedness stereotype

  • Claim: People who wear glasses (associated with nearsightedness) show a link with higher IQ on average.
  • Testing outcome: A study involving faces with vs. without glasses found people did not perceive glasses wearers as more intelligent—so the effect isn’t explained by a simple “glasses look smart” bias.
  • Proposed explanations:
    • Less outdoor light exposure early in life: higher-IQ kids might spend more time indoors.
    • More close-up work: reading/studying could contribute to nearsightedness.

“Useful” IQ correlations (especially health-related)

The video frames these as factors that can guide real-life choices (even though causality isn’t always fully settled).

Negative factors (linked to lower IQ)

  • Toxins
    • Example: Lead poisoning, especially in children → lower IQ.
  • Sleep apnea
    • Signs: waking unrefreshed + loud snoring → consider doctor evaluation
    • Emphasis: treatable
  • High blood pressure (older adults)
    • Linked to reduction in IQ over time
  • Adult hearing loss
    • Loss of hearing tends to precede reductions in IQ
    • Causality is uncertain, but treating hearing loss is recommended for additional benefits too.

Positive factors (linked to higher IQ)

  • Proper nutrition, especially during childhood.

  • Health behaviors

    • Maintain a healthy diet
    • Exercise regularly

  • Causality caveat: The speaker notes that associations may be confounded (e.g., poverty can lead to worse nutrition and lower IQ), so not every correlation proves direct cause.

Emphasis on stronger causal candidates

The speaker suggests there’s relatively better reason to think some factors play causal roles, particularly:

  • Head trauma
  • High blood pressure

Method lesson: improve performance without “raising IQ”

A key takeaway is presented as a practical principle:

  • You can get better at almost any task by:

    • Practicing the task
    • Getting good feedback

  • Implication: A person who studies/practices a domain for years can outperform someone with higher IQ but no practice in that domain.

Correlations between IQ and beliefs / values

Religiosity

  • Claim: Higher-IQ people tend to be less religious.
  • Possible explanation: More likely to question beliefs they were born into (since most people are born into a religion and tend to remain with it).

Free speech / tolerance of disagreement

  • Claim: Higher-IQ people are more likely to support free speech for people they disagree with—even for groups they strongly oppose (examples given: Christian fundamentalists, neo-Nazis).

Expected correlations that don’t show up (or are weak)

IQ vs happiness / life satisfaction

  • Claim: There’s no link between IQ and happiness (life satisfaction).
  • Why this is framed as strange: IQ correlates with advantages like wealth and job performance, so one might expect higher IQ to improve well-being—yet it doesn’t.

IQ vs conscientiousness / diligence

  • Claim: Studies find no correlation or a very small negative correlation between IQ and conscientiousness traits (diligence, organization, hard work).
  • Possible interpretation offered: Conscientious people may appear smarter due to behaviors like studying and staying in school, but that doesn’t necessarily mean higher IQ.

Book / channel promotion (stated methodology overview)

  • Speaker promotes their book: The 12 Levers
  • Described approach:
    • Deep dive into 100+ self-improvement books
    • Review 20+ types of therapy
    • Extract each technique/method
    • Conclude there are 12 main psychological strategies to improve life
  • Call to action:
    • Website: 12leversbook.com
    • Subscribe for weekly psychology deep dives

Speakers / sources featured

  • Speaker (primary): Unnamed narrator/host (not identified in the subtitles)
  • Referenced researchers / concept sources:
    • “Giant IQ study involving over 3,000 people” (study referenced by the speaker; not specifically named)
    • Dunning–Kruger effect (concept)
  • Books referenced (speaker’s work):
    • The 12 Levers (speaker’s book; co-author mentioned but not named)
    • The 12 Levers website: 12leversbook.com

Original video