What do intelligence researchers really think about intelligence?
There are many reasons for intelligence researchers to keep their opinions to themselves. Intelligence research raises strong emotions, not all of them positive, and a researcher saying the wrong thing in public can lead to disputes, loss of funding, general harassment and sometimes a loss of job.
So, when finding out about real opinions, anonymity is required. Rindermann, Coyle and Becker have replicated the last survey on experts done 30 years ago.
That's the big survey done by Stanley Rothman and Mark Snyderman in the 1980s.
Researchers were invited to participate only if they had recent intelligence-related publications in Intelligence, Cognitive Psychology, Biological Psychology, Journal of Mathematical Psychology, Contemporary Educational Psychology, Journal of School-Psychology, New Ideas in Psychology, and Journal of Applied Developmental Psychology.
Invitations were emailed to 1237 persons and at the end only 228 (18%) participants completed the process (70 fully and 158 partially). As far as the authors could make it out, “lefties” and “righties” turned down the offer in equal numbers, complaining that the questions were not good enough, the selection of experts would not be good or that they did not want to participate in a process which suggested that the truth could be found by majority decisions. In fact, the authors just wanted to find out what expert opinion was, in all its variety, and were not intending to come to any conclusions of a majority sort. (Perhaps climate research has poisoned the academic atmosphere, and no-one wants to be involved with anything which smacks of consensus science). As many pointed out, one good study can smash down an old consensus.
Experts agreed that the following were sources of reasonable evidence for significant heritability of intelligence: monozygotic twins reared apart, comparisons of monozygotic and dizygotic twins, adoption studies, “patchwork” family studies.
Asked: Is there sufficient evidence to arrive at a reasonable estimate of the heritability of intelligence in populations of developed countries?” 73% said Yes.
Asked: What are the sources of U.S. black-white differences in IQ?
0% of differences due to genes: (17% of our experts)
0-40% of differences due to genes: 42% of our experts
50% of differences due to genes: 18% of our experts
60-100% of differences due to genes: 39% of our experts
100% of differences due to genes: (5% of our experts)
M=47% of differences due to genes (SD=31%)
Like I always say, "Fifty-Fifty" is a pretty reasonable rule of thumb that won't lead you too far astray. It may not be the most accurate, but it's the best for reminding you to stay balanced: this is a complicated subject.
As far as I can see, there are two extreme positions, the 17% who think that the difference is none of it due to genes, and the 5% who think it is all due to genes. The rest are in the middle, and the “consensus” is that 47% of the difference is due to genes. (See above why one should not get too excited about consensus results). All this is obviously very different from the public narrative, which is that 0% of the difference is due to genes. Such a view is rejected by the majority of experts, but there is still a sizeable minority of experts who hold that view. In sum, there are a variety of opinions.
Asked: What is the influence of average cognitive ability level and highly cognitive competent persons on positive development of society, the economy, technology, democracy and culture? All of the results were above the mid point, suggesting agreement about a positive relationship between high intelligence and social progress.
Asked about measurement bias: a majority thought that test taker motivation and anxiety were important, the race of the examiner much less so.
Asked: Is there racial/ethnic content bias in intelligence tests? The mean agreement was 2.13 out of 4.
Asked whether there was bias against lower SES and Africans in the western world, the mean agreement was about 4 out of 9.
Only a minority wanted separate norms for minority groups.
Out of 26 media sources on intelligence, only 3 were rated better than 5 out of 9:
Experts rated public debates on intelligence as twice as likely to be ideological than scientific. I think it is plain that most experts do not regard the press as being much good at reporting intelligence. Stories of marginal importance tended to be paid too much attention.
They thought the Flynn Effect was due to educational and other environmental causes. The most important factors for cognitive ability differences between nations were education 21% and genes 15%.