Category Archives: I.Q.

In light of the previous post I was curious about the literature on inbreeding depression of IQ. A literature search led me to conclude two things:
– This is not a sexy field. A lot of the results are old.
– The range in depression for first cousin mar…

Read more

In light of my previous posts on GRE scores and educational interests (by the way, Education Realist points out that the low GRE verbal scores are only marginally affected by international students) I was amused to see this write-up at LiveScience, Low IQ & Conservative Beliefs Linked to Prejudice. Naturally over at Jezebel there is […]

Read more

A questioner below was curious if vocabulary test differences by ethnic and region persist across income. There’s a problem with this. First, the INCOME variable isn’t very fine-grained (there is a catchall $30,000 or greater category). Second, it doesn’t seem to control for inflation. But, there is a variable, DEGREE, which asks the highest level of […]

Read more

The title says it all, and I yanked it from a paper that is now online (and free). It’s of interest because of its relevance to the future genetic understanding of complex cognitive and behavioral traits. Here’s the abstract: General intelligence (g) and virtually all other behavioral traits are heritable. Associations between g and specific […]

Read more

I saw this link posted on twitter, IQ and Human Intelligence: An interesting finding from genetic research, which Mackintosh mentions, only in passing, as posing a problem in the estimation of the heritability of g, is that there is greater assortative mating for g than for any other behavioral trait; that is, spouse correlations are […]

Read more

A new paper in Molecular Psychiatry has been reported on extensively in the media, and readers have mentioned it several times in the comments. I read it. It’s titled Genome-wide association studies establish that human intelligence is highly her…

Read more

Check out the discussion at Steve Sailer’s weblog. People always ask my opinion on this issue. All I’d say is this: don’t bet against the Chinese.

Read more

Update: Stephen Dubner emailed me, and pointed me to this much longer segment which has a lot of Bryan Caplan. So it seems like the omission that I perceived was more of an issue with the production and editing process and constraints of the Marketplac…

Read more

In my experience most scientists are not too clear on the details of intelligence testing, perhaps because the whole area is somewhat in ill repute (except when you want to brag about your own SAT/GRE score!). This despite the fact that the profession …

Read more

WORDSUM is a variable in the General Social Survey. It is a 10 word vocabulary test. A score of 10 is perfect. A score of 0 means you didn’t know any of the vocabulary words. WORDSUM has a correlation of 0.71 with general intelligence. In other w…

Read more

Image credit: Aleksandra Pospiech One of the interesting and robust nuggets from behavior genetics is that heritability of psychological traits increases as one ages. Imagine for example you have a cohort of individuals you follow over their lives. At the age of 1 the heritability of I.Q. may be ~20%. This means that ~20% of […]

Read more

Jonah Lehrer has a post up, How Preschool Changes the Brain over at Frontal Cortex. He reports on a paper, Investing in our young people, which has been around for about 5 years. The top line of it is this, an investment in a $2,500/year (inflation adjusted) pre-school program in the early 1960s seems to […]

Read more

12/12
Razib Khan