THREAD: 12 Things Everyone Should Know About IQ

1. IQ is one of the most heritable psychological traits – that is, individual differences in IQ are strongly associated with individual differences in genes (at least in fairly typical modern environments). https://t.co/3XxzW9bxLE

2. The heritability of IQ *increases* from childhood to adulthood. Meanwhile, the effect of the shared environment largely fades away. In other words, when it comes to IQ, nature becomes more important as we get older, nurture less. https://t.co/UqtS1lpw3n
3. IQ scores have been increasing for the last century or so, a phenomenon known as the Flynn effect. https://t.co/sCZvCst3hw (N ≈ 4 million)

(Note that the Flynn effect shows that IQ isn't 100% genetic; it doesn't show that it's 100% environmental.)
4. IQ predicts many important real world outcomes.

For example, though far from perfect, IQ is the single-best predictor of job performance we have – much better than Emotional Intelligence, the Big Five, Grit, etc. https://t.co/rKUgKDAAVx https://t.co/DWbVI8QSU3
5. Higher IQ is associated with a lower risk of death from most causes, including cardiovascular disease, respiratory disease, most forms of cancer, homicide, suicide, and accident. https://t.co/PJjGNyeQRA (N = 728,160)
6. Higher IQ is associated with lower rates of most forms of mental illness. https://t.co/0jX1og7xHV (N = 1,049,663)
7. More generally, IQ tests are among the most reliable, predictive measures in psychology – one of the field's crowning achievements. https://t.co/a9z9GPQYuD

If IQ isn't a valid concept, no concept in psychology is valid.
8. Despite this, many people are allergic to the concept of IQ. Ironically, this includes many intellectuals. https://t.co/ThPkVT8apc
9. Perhaps as a result, there's some evidence that researchers are less likely to publish studies showing a link between IQ and grades – the reverse of the usual publication bias for positive findings. https://t.co/gTiKmmarTB; although see https://t.co/sYEgBnaJkO
10. The antipathy to IQ is unfortunate. IQ predicts all things good. Interventions to boost IQ (such as salt iodization) could greatly enhance human well-being. https://t.co/LHVqClN2kE

Conversely, IQ-denial could cause real harm by stalling the development of such interventions.
11. IQ testing has other potential benefits as well. One of my favourite studies of the last few years found that universal IQ screening boosts the number of poor, female, and minority students in gifted education. https://t.co/5at8wNjKe8

Figure: https://t.co/fogF8GyO8Z
12. Last but not least, here's a list of ten common myths about IQ. https://t.co/DOTDWhMoyS HT @StuartJRitchie

More from Steve Stewart-Williams

39.1% of Democrats think that it's wrong to negatively stereotype people based on their place of birth... AND that Southerners are more racist. https://t.co/yp1hviLuBB


65.2% of Republicans think that people shouldn't be so easily offended... AND that Black Lives Matter is offensive.
https://t.co/znmVhqIaL8


64.6% of Democrats think that a woman has the right to do what she wants with her body... AND that selling organs should be illegal.

48.5% of Democrats think that a woman has the right to do what she wants with her body... AND that prostitution should be illegal.


57.9% of Republicans think that people should be free to express their opinions in the workplace... AND that athletes should not be allowed to sit or kneel during the national anthem. https://t.co/ds2ig1NJFr


Democrats: Men and women are equal in their talents and abilities. Also, women are superior. https://t.co/bEFSmqQguo

 

THREAD: My Top 12 Favourite Perceptual Illusions

1. A great example of how expectations guide perception.


2. The horizontal lines in this image are all parallel.
https://t.co/Y0o0hd8R15 HT @victoria1skye


3. The circles in this image are all the same colour. https://t.co/H4Prys8l0n


4. This isn't a GIF – the movement is all in your head.


5. This looks two photos of the same road, taken from different angles. But it’s just the same photo twice. https://t.co/pdq0iRynFw


Original Tweet