The Latest On Intelligence

http://www.danielwillingham.com/1/post/2012/05/the-latest-on-intelligence.html

by danielford • 14 years ago

218 163 14 years ago

Symmetry7• 14 years ago

"The extent to which genes matter to intelligence varies by social class (genetic inheritance matters more if you're wealthy, less if you're poor)."

It's always seemed obvious to me that this ought to be true - that is that environment will matter more if you have greater differences in environment. In the extreme case if you feed kid A and don't feed kid B, then kid A will end up with an infinitely greater IQ than kid B.

scott_s10• 14 years ago

Be careful about coming up with an explanation for a result, and then thinking it is obvious: http://lesswrong.com/lw/im/hindsight_devalues_science/

tokenadult5• 14 years ago

Scott, that is a correct point, but that important warning works both ways in many controversies about scientific findings on issues that people think they know about from personal experience. Human intelligence research, when discussed among laymen, is particularly an area in which people make strong claims on the basis of "it's obvious that" or "everyone knows" when the strong claims are neither obvious nor things that everyone knows.

The way to reality-check someone's impression of how the world works is to gather more data. In human intelligence research, James R. Flynn (a co-author of the paper under review here) has enjoyed particular success in making claims that run against the "everyone knows" bias of individual differences psychologists, and then being backed up by other psychologistics (and getting published in the top journals in psychology) when data are found to back him up.

Here is what Arthur Jensen said about Flynn quite a few years ago, and he hasn't retracted this statment: "Now and then I am asked . . . who, in my opinion, are the most respectable critics of my position on the race-IQ issue? The name James R. Flynn is by far the first that comes to mind." Modgil, Sohan & Modgil, Celia (Eds.) (1987) Arthur Jensen: Concensus and Controversy New York: Falmer. Here's what Charles Murray (all right, neither a psychologist nor a geneticist, but, as the review points out, an author who has written about these issues) says in his back cover blurb for Flynn's book What Is Intelligence?: "This book is a gold mine of pointers to interesting work, much of which was new to me. All of us who wrestle with the extraordinarily difficult questions about intelligence that Flynn discusses are in his debt." As N. J. Mackintosh writes about the data Flynn found in his book IQ and Human Intelligence: "the data are surprising, demolish some long-cherished beliefs, and raise a number of other interesting issues along the way." Flynn has earned the respect and praise of any honest researcher who takes time to read the primary source literature. Robert Sternberg, Ian Deary, Stephen Pinker, Stephen Ceci, Sir Michael Rutter, and plenty of other eminent psychologists recommend Flynn's research.

bluekeybox• 14 years ago

Very interesting point, but I'd argue it has different implications to different fields of study. In physics, for example, if ten years from now it turned out that the existence of Higgs boson, in hindsight, was an "obvious" part of a wonderfully intuitive theory, most physicists would be elated and consider it a proof of the strength of their theory. Arguably a different story in social science.

Symmetry7• 14 years ago

I'm sorry if I ended implying I was using hindsight, I meant to claim that this was obvious to me in advance. I'm pretty sure its even in my comment history where we were discussing someone's claim that IQ wasn't a real thing even though it was a heritable thing, and I asserted that "there isn't just one heritability of IQ" or words very close to that.

mistercow2• 14 years ago

The point is actually more subtle than that though. What they're saying is that holding social class constant, genetic difference is more important for the wealthy than the poor.

For example, kid A and kid B are both wealthy and have significant genetic differences related to factors affecting intelligence. In this case kid A and kid B are likely to have significantly different intelligence from each other.

Conversely, kids C and D are both poor and have similar genetic differences to A and B. They will show much less difference in intelligence from each other.

That fact is certainly not obvious, but it is fascinating.

kenjackson2• 14 years ago

Right. The implication, in my mind at least, is that fighting poverty should be one of the key goals of society. Being in poverty effectively hides gifts as poverty will dominate "natural" ability.

Symmetry7• 14 years ago

The mental model I'm using here is that IQ is the result of something like (Genetic g) * diminishing_returns(nutrition). And that nutrition is something like K1*(social_factor) + K2 + noise(). So noise is going to result in smaller deviations when the social_factor is higher.

Before reading that website I would have expected that variations in the first term for nutrition would be small compared to the second term, so I wouldn't have necessarily expected this to show up between affluent and poor kids in the US. But between affluent kids in the US and kids from sub-Saharan Africa I certainly would have.

EDIT: In fact, I would have guessed the working-class/middle-class IQ differences were an order of magnitude lower.

brittohalloran2• 14 years ago

I think it implies that if you're wealthy, you are able to fully meet your intellectual potential, thus the greater spread for wealthy children.

jfoutz• 14 years ago

Feel free to ignore me, i've got nothing to hold up as any kind of authority on the subject, but i'm curious if my thinking is irrational.

I'd thought genetics only mattered for the elite. I'd always used the olympics as an example of this. Take a few hundred people with the best drive, nutrition, and training from all over the world. What's left to set them apart? genetics.

If you're not elite, who cares? you can just eat better, work harder, train smarter, whatever.

To put it another way, how often is genetics the limiting factor? If you've really done all you can do to improve, then you can blame stuff you can't actually do anything about, like genetics.

tokenadult5• 14 years ago

I would upvote this twice if I could. I have read the underlying paper

Nisbett, R. E., Aronson, J., Blair, C., Dickens, W., Flynn, J., Halpern, D. F., & Turkheimer, E. (2012, January 2). Intelligence: New Findings and Theoretical Developments. American Psychologist, 67, 130-159.

http://psychology.msu.edu/pers_hambric3/PSY493%20Spring%2020...

Daniel Willingham reviews in the submitted post, and the paper is a joint review article on the last decade and a half of research on human intelligence by an all-star group of researchers.

After edit: I see other comments are asking about what the research shows about genetic influences on IQ and environmental influences on IQ. Here is some FAQ information on that, originally part of another comment I posed here on HN:

The researchers in the Behavior Genetics Association are making increasingly cautious statements about genetic influence on human behavioral traits as more data are amassed. Here are some of the latest statements by some of the leading researchers.

Turkheimer, E. (2012). Genome wide association studies of behavior are social science. In K. S. Plaisance & T.A.C. Reydon (Eds.) Philosophy of Behavioral Biology (pp. 43-64). New York, NY: Springer.

http://people.virginia.edu/~ent3c/papers2/Turkheimer%20GWAS%...

"If the history of empirical psychology has taught researchers anything, it is that correlations between causally distant variables cannot be counted on to lead to coherent etiological models."

Johnson, W., Turkheimer, E., Gottesman, I. I., & Bouchard, T. J. (2009). Beyond heritability: Twin studies in behavioral research. Current Directions in Psychological Science, 18, 217-220. [I am personally acquainted with three of the four co-authors of this paper, one of whom regularly exchanges links with me by email.]

http://people.virginia.edu/~ent3c/papers2/Articles%20for%20O...

"Moreover, even highly heritable traits can be strongly manipulated by the environment, so heritability has little if anything to do with controllability. For example, height is on the order of 90% heritable, yet North and South Koreans, who come from the same genetic background, presently differ in average height by a full 6 inches (Pak, 2004; Schwekendiek, 2008)."

Turkheimer, E. (2008, Spring). A better way to use twins for developmental research. LIFE Newsletter, 2, 1-5.

http://people.virginia.edu/~ent3c/papers2/Articles%20for%20O...

"Unfortunately, that fundamental intuition is wrong. Heritability isn’t an index of how genetic a trait is. A great deal of time has been wasted in the effort of measuring the heritability of traits in the false expectation that somehow the genetic nature of psychological phenomena would be revealed. There are many reasons for making this strong statement, but the most important of them harkens back to the description of heritability as an effect size."

Alex39172• 14 years ago

Not sure if this is true, but I heard recently that the best predictor of IQ is actually the gene that controls determines the size of your mom's vagina, because that is what mediates the risk of brain cell loss due to lack of oxygen at birth. Kind of a funny, but also quite telling about the state of genetics.

sp3322• 14 years ago

That is funny, but babies "breathe" through the umbilical up to several minutes after birth, so I'm sure it has nothing to do with "brain cell loss" or oxygen.

rada• 14 years ago

Given the prevalence of c-sections and episiotomies, highly unlikely. In 2010, a full third of US babies were not born through the vagina.

tokenadult5• 14 years ago

Not sure if this is true

That's definitely NOT a well replicated finding. In general, no study has ever shown any single-gene allele variation with strong effect on IQ across the general population. There are rare genes (but, really, mostly rare chromosome abnormalities) that have devastating effect on IQ, resulting in mental retardation, but the variance in IQ in the general population above and below the population median is still quite mysterious as to whatever genetic basis it has, as the references I've already shared in this thread will make clear.

After edit: has anyone got a contrary example to the general statement I'm making here? I gather someone disagrees with the statement, but I'm not seeing any citations posted in reply. Feel free to check the citations I've already posted in other replies in this rapidly ramifying thread if you disagree with me and would like to look up facts on the matter.

gwern6• 14 years ago

My problem with upvoting is that I have read the underlying paper, and I'm not impressed at all. This paper takes a hugely nurturist approach, and at parts verges on dishonesty.

I consider myself - if not an expert, at least very well informed - on the topic of dual n-back and I was flabbergasted when I read pg11 of the PDF. There is not a single mention of the many failures to replicate, methodological critiques, or skeptical meta-analyses about n-back. Some of that can be explained by the January 2012 date, but only a very some of it because a lot of that long predates 2012 or 2011, and it can't be explained by the people involved being ignorant because they thank Jaeggi, Duckworth, Jonides, and Sternberg - who certainly would know!

Someone reading this paper would come away with a very different understanding and expectation for dual n-back training than someone reading my http://www.gwern.net/DNB%20FAQ . So all I can think is, "if this is how Nisbett et al act on the one section where I know almost as much as them, how are they misleading me in all the other sections?"

slurgfest7• 14 years ago

Labeling the paper with the epithet "hugely nurturist" tells nothing about the paper but everything about what you are doing. You are attempting the early dismissal of some viewpoint you disagree with on a more or less political grounds but this has not very much to do with science.

Most cognitive tasks used inside an MRI are about as meaningless as benchmarks. It seems gratuitous to turn this into evidence of intentionally dishonest malfeasance and frame the whole thing as some kind of pseudo-political debate. Just engage the data, please?

Setting aside the political tone you've taken here: the idea that nature and nurture are dichotomous (or can even be meaningfully separated) is not supportable.

It has been observed many times that because heritability includes a genes x environment interaction term, it does not mean that something is 'genetic' - and real-world examples have been provided in this thread.

You cannot build an adequate understanding of development on the caricature that there is a dichotomy between 'nature' and 'nurture'. DNA and RNA cannot do anything without a developmental environment. You do not have any organism without development, which necessarily occurs in an environment. There are strong adaptive reasons for learning in big primates and it is well known to occur. On the other hand, you do not have development or learning without machines to implement them; these are not built without genes but neither can genes build them in a vacuum. It is a perpetual interchange and the components are viciously complementary and embedded in the same feedback loops to a point where it is nearly meaningless even to argue about nature vs. nurture.

realitygrill• 14 years ago

At least you're not succumbing to the Gell-Mann Amnesia effect, gwern.

obtu3• 14 years ago

It sounds like you are hijacking the paper to talk about a pet theory. Did you find a cite on p11 about DNB? They refer to cognitive exercise, but not using that particular method. Whether that method is effective or not is orthogonal to their point.

kenjackson2• 14 years ago

This is an interesting result noted from the paper: "Even when improvements in IQ produced by the most effective early childhood interventions fail to persist, there can be very marked effects on academic achievement and life outcomes."

As noted by the author, this suggests that IQ only captures a portion of early childhood intervention benefits. And goes counter to those who suggest that early intervention programs serve no purpose if IQ doesn't remain high (IOW, IQ is only a portion of what constitutes success in life).

Xcelerate6• 14 years ago

I didn't read the entire paper, but to someone who did, how much of a link is there between genetics and IQ? I know this isn't a popular subject, but if I remember correctly I believe that Ashkenazi Jews constitute 3% of the population yet have won 27% of the Nobel prizes in science.

I would think that much like how different types of people from different regions have differing athletic capabilities, there would also be differences in mental facilities as well -- some better at music, some better at math, etc. Thoughts?

readme• 14 years ago

>but if I remember correctly I believe that Ashkenazi Jews constitute 3% of the population yet have won 27% of the Nobel prizes in science.

Can we get a citation on this?

scott_s10• 14 years ago

"Nobel Prizes have been awarded to over 800 individuals, of whom at least 20% were Jews, although Jews comprise only 0.2% of the world's population.": http://en.wikipedia.org/wiki/List_of_Jewish_Nobel_laureates

Although this need not be explained by genetics. It could just as easily be explained by culture.

psykotic• 14 years ago

Page 3 of Natural History of Ashkenazi Intelligence: "During the 20th century, they made up about 3% of the US population but won 27% of the US Nobel science prizes and 25% of the ACM Turing awards. They account for more than half of world chess champions."

http://harpending.humanevo.utah.edu/Documents/ashkiq.webpub....

praptak• 14 years ago

Both scientific and athletic achievements have an alternative explanation: culture. If there was a good sample of adopted children from a group with such achievements, one could examine these hypotheses in more detail.

Xcelerate6• 14 years ago

Right, but my question is for only the genetic effects (even with adopted children of different cultures there will be other differences that are not genetic). It would be difficult to determine, but there are enough statistical techniques that one could get a good idea. Surely different races can't have identical distributions of various "skills" -- the only question is how much they are offset from each other.

jessriedel2• 14 years ago

These kind of studies have been done, and it is my recollection that genetics still appear to have a significant impact. Of course, people can still argue that various sociological effects can explain most of this, like lowered expectations for certain races, etc.

Would love to see some cites.

Juniper• 14 years ago

That's an incredible statistic. If the cause is cultural then it's a wonder there isn't a plethora of books advising on how to raise children the Ashkenazi way. Are there any such books?

leoedin2• 14 years ago

Certainly culture plays a role, but it's hard to argue that the reason a non-representative proportion of olympic runners are black is due to culture. http://static.guim.co.uk/sys-images/Sport/Pix/pictures/2008/... really demonstrates this fact.

What that picture doesn't show, though, is that there are a lot of almost-world-class sprinters who are european, asian or of other ethnicities. The edge that being of a certain ethnic background gives you in sprinting is only really important at the very top of the competition. I'd imagine that for the majority of people, training and dedication make up a far larger component of their success or failure at sprinting.

Interestingly, in the article it indicated that genetics appeared to play a bigger role in the intelligence of wealthy people. I'd imagine this is a similar situation. Genetics may give you a slight edge at the very top of academia, but otherwise education is the key.

Education is the low hanging fruit in increasing overall intelligence.

mynameishere• 14 years ago

People always ask this incorrectly. The real question is "To what degree does genetics determine the difference of average IQs between groups." The link between genetics and IQ is near 100% in an absolute sense, as tapeworms and dogs generally will score a 0 on any test.

Even the worst possible environment...say, repeated concussions to the head via a hammer, will still result in a human scoring far above any non-human.

yesbabyyes• 14 years ago

Even the worst possible environment...say, repeated concussions to the head via a hammer, will still result in a human scoring far above any non-human.

I'm pretty sure you're wrong. I think research suggests that dolphins, parrots, bonobos and some other animals have tested higher than humans.

streptomycin• 14 years ago

It says a lot about it. For instance:

"She examined the IQs of Black and mixed- race children averaging 8.5 years of age who were adopted by middle-class families who were either Black or White. The children who were of half-European origin had virtually the same average IQ as the children who were of exclusively Black origin. Hence European genes were of no advantage to this group of 'Blacks.' Children (both Black and mixed-race) adopted by White families had IQs 13 points higher on average than those adopted by Black families, indicating that there were marked differences in the environments of Black and White families relevant to socialization for IQ; indeed, the differences were large enough to account for virtually the entire Black–White gap in IQ at the time of the study."

It says less about Jews in particular, which I'd guess is because of a lack of data. There's not a heck of a lot of Jews up for adoption, relative to blacks. But it does note:

"It is important to note that even at the highest estimates we have of Jewish IQ, Jewish accomplishment exceeds what would be predicted on the basis of IQ alone. Nisbett (2009) has argued that the numbers of Jewish Ivy Leaguers, professors at elite colleges, Supreme Court clerks, and Nobel Prize winners are greater than one would expect even if average Jewish IQ were 115. He has also noted that remarkable as the superior achievement of Jews is, the achievement difference between Jews and non-Jews is far less extreme than differences between groups in many other comparisons that cannot be explained on purely genetic grounds, such as the achievements of the Italians versus the English in the 15th century, of the English versus the Italians after the 18th century, of Arabs versus Europeans in the 8th century, of Europeans versus Arabs after the 14th century, and of New Englanders versus Southerners throughout American history."

While it is certainly plausible that there is some big genetic influence on intelligence due to ethnicity, like there is in athletics, we have yet to find convincing evidence of it.

zone411• 14 years ago

What's important to note here is that, assuming normal distribution, group differences can account for large differences in the number of individuals at the very top (and bottom). If a group A has a mean IQ of 100 and group B has a mean IQ of 110, group B will have four times more individuals with IQ over 130 than group A.

Dn_Ab• 14 years ago

Kevin Mitchell has a very interesting take on intelligence here: http://wiringthebrain.blogspot.com/2012/07/genetics-of-stupi...

Basically he suggests thinking about the formation of intelligence to be something like trying to run an obstacle course while holding an armful of things and trying to drop as little as possible. Essentially, he is arguing that there is some optimal or standard brain and since any mutation introduced into the brain is more likely to be harmful than beneficial, more intelligent individuals are not those that inherited some specific genes for intelligence but are most likely those who avoided the most damaging non-specific mutations.

That’s [runaway selection of intelligence boosting genes] all nice, though admittedly speculative, but those mutations are the ones that we would expect to not vary in human populations – they would now be fixed. In particular, there is little reason to expect that there would exist new mutations in such genes, present in some but not all humans, which act to further increase intelligence.

To test this he suggests using symmetry as a proxy for robustness in the individual. This fits well with the fact that all attempts thus far to find a common genetic basis for intelligence have failed, the correlation between intelligence and immune function, ideas that intelligence was indirectly selected when optimizing for healthy mates and findings that Nootropic like substances tend to have the least effect on already intelligent minds. In the last case, it is interesting to note nootropics should then be viewed not cheating but more leveling of the playing field. Taking this further, genetics are not the only obstacle course - there is still variation in the womb environment and early childhood. The interplay of genes and the stability of process in the growing brain; affected by a lack of stimulation, poor nutrition and a stressful womb environ would likely have more impactful effects on intelligence than pure genetics.

OmegaHN3• 14 years ago

This article is very hard to digest because of the writers switching of "intelligence" and "IQ". Intelligence =/= IQ. IQ is a score on a test, and intelligence is a vague set of mental skills and processes to solve problems of varying degrees and subjects. To say that they are equal is like saying that athleticism is equal to the number of pounds you can bench.

If the writer is talking about IQ, then these investigations aren't interesting, as IQ is a very small subset of intelligence (the ability to solve those types of problems on a test, which you can easily train for). If the writer is talking about general intelligence, then the writer really shouldn't be mentioning IQ at all, as it is notorious for being confused as actual intelligence.

slurgfest7• 14 years ago

Any argument containing the word "intelligence" at all is hard to digest, because the idea is so totally vague as to be useless.

Unless you operationalize it as something measurable. Such as IQ.

There is no point talking about intelligence in the abstract unless you can actually say what you actually mean in such a way that 30 readers won't develop 30 completely different interpretations of what it is you are saying.

What is "actual intelligence"? And let's not, like Humpty Dumpty, say that words mean just what we choose them to mean.

Xcelerate6• 14 years ago

Without a consistent, objective definition, "intelligence" makes no sense. If you would like to dissociate IQ and intelligence, go ahead, but IQ is a metric that has correlations with many other factors (test performance, income, a whole slew of things really).

OmegaHN3• 14 years ago

Correlations mean almost nothing. Just going off your list:

-IQ:Test Performance - Of course. IQ is a grade off of a test. It correlates with itself. If you mean tests such as the SAT or tests in a school, then yes, IQ does help somewhat with that, as it was designed to (the first IQ test, created by Alfred Binet, was designed to find students who would not do well in a regular school environment). However, do high test scores mean high intelligence? Not necessarily, as most test scores can be improved drastically with a class focusing only on the test, showing different tricks that the test maker's use. Same with IQ tests.

-IQ:Income - Income (generally) means higher education level, and modern education teaches the general forms of questions asked on tests, such as the IQ tests. Education trains the mind to think along the lines of what the IQ test uses to grade performance. Also, spoken another way, if IQ (which is "intelligence") correlate with income, then one can say that income correlates with IQ ("intelligence"). If this correlation is weak, then it is meaningless. If it is strong, then that is a very strong evidence for eliminating the lower classes to raise the "intelligence" level of a nation.

Most other factors follow along these lines. The problem with correlation is that it is not, in any way, a suggestion or a proof of causation. There can be infinitely many other factors that can be influencing the two.

I do agree that without a consistent, objective definition, one cannot possibly study intelligence. However, IQ is not a good definition of intelligence. At best, it tests "academic" intelligence, and at worst, it tests test-taking ability.

Taking from Wikipedia:

>"Individuals differ from one another in their ability to understand complex ideas, to adapt effectively to the environment, to learn from experience, to engage in various forms of reasoning, to overcome obstacles by taking thought. Although these individual differences can be substantial, they are never entirely consistent: a given person's intellectual performance will vary on different occasions, in different domains, as judged by different criteria. Concepts of "intelligence" are attempts to clarify and organize this complex set of phenomena. Although considerable clarity has been achieved in some areas, no such conceptualization has yet answered all the important questions, and none commands universal assent. Indeed, when two dozen prominent theorists were recently asked to define intelligence, they gave two dozen, somewhat different, definitions." -APA report quoted in the article.

character• 14 years ago

Daniel Willingham knows a lot about this subject (I took into to cognition with him a couple of years ago). Of course in the linked article he is just paraphrasing other people's work, but he does a lot of similar stuff himself especially on developmental neuroscience in learning and reasoning. It is very interesting to be taught by someone who knows a ton about learning and how to learn from the neurological point of view.

brittohalloran2• 14 years ago

Great quote from page 8 of the actual report:

"In particular, there is clear evidence that school affects intelligence."

randomdata2• 14 years ago

Intelligence is traditionally measured through testing. School is the only place people generally practice test taking. Ergo, it makes sense that school affects the results of intelligence tests, but perhaps not in the way you might initially think.

Tichy• 14 years ago

In a good way, or a bad way?

rikelmens3• 14 years ago

The best investment a parent can make to improve the child's IQ is DHA, omega 3 fatty acid. It is a key ingredient of a brain, and a typical diet is very deficient in DHA.

http://www.diseaseproof.com/archives/healthy-pregnancy-does-...

Additionally, checkout the: http://www.omega3.org/

gwern6• 14 years ago

Most of the fish oil/IQ links I know tend to either be poor quality studies, show no effect, or show a fade-out... For example,

> Supplementation of a mother’s diet during late pregnancy and 3 months postpartum with long-chained fatty acids has also been demonstrated to improve cognitive performance in human children (Helland et al. 2003). http://www.pediatricsdigest.mobi/content/111/1/e39.full

But to follow up: Helland et al 2008 http://pediatrics.aappublications.org/content/122/2/e472.sho...

> CONCLUSION. This study suggests that maternal concentration of n-3 very-long-chain polyunsaturated fatty acids during pregnancy might be of importance for later cognitive function, such as sequential processing, although we observed no significant effect of n-3 fatty acid intervention on global IQs. Neonatal fatty acid status had no influence on BMI at 7 years of age.

(One may not be surprised inasmuch as most efforts to boost IQ in kids like the Abecedarian project show fadeout.)

rikelmens3• 14 years ago

I agree in regard of fish oil quality. That's why I use algae derived DHA supplements.

zmoney• 14 years ago

This article should be titled, “The latest findings on IQ” because IQ score and “intelligence” in a general sense are very different things. Plenty has been published on the inherent cultural and gender biases in IQ testing.

Statements like “when babies from poor families are adopted into wealthy families, their IQ goes up” are almost devoid of information because the IQ test itself favors the type of “intelligence” valued by the educated, wealthy class.

Xcelerate6• 14 years ago

I thought it would be interesting to note that my karma score seems to be going up and down a lot on this topic in short periods of time. On other topics, it seems to increase slowly. I'm trying to think of what deeper conclusions could be drawn from this that people have what appear to be strong and varying opinions on something that should be rather scientific and objective.

roguecoder2• 14 years ago

It can't be scientific and objective, because it is not measuring something scientifically and objectively defined and most of the differences being discussed can be erased by manipulating the testing circumstances.

That doesn't mean it is never worth measuring, but it seems particularly silly to obsess over IQ when better data on actual outcomes exists for things like educational interventions. The best applications of IQ are in identifying areas of deficit in individuals (one definition of learning disability is an area of cognitive performance that varies significantly from all others.) The worst applications of IQ are to funnel more resources to already-advantaged children or to make demographic generalizations. Given that, it hardly seems unreasonable to mostly ignore the IQ-obsessed research and focus on specific, repeatably-defined cognitive tasks instead.

justin_vanw4• 14 years ago

"A great deal of time has been wasted in the effort of measuring the heritability of traits in the false expectation that somehow the genetic nature of psychological phenomena would be revealed."

There is a strong cultural bias among much of the research community to go out of their way to deny any genetic factors in intelligence. Perhaps this is well intentioned, but it is absurd.

I have come across very few squirrels that have mastered fire, or could be taught calculus, or even addition. I doubt that this is cultural or due to the squirrels upbringing, diet, social status, or how many books the squirrel has available to it, or the quality of it's teachers, or pathogens. Clearly then, it is possible for genetics to completely dominate other factors in determining intelligence. In the animal kingdom at large heredity/genetics account for basically all of the variation in intelligence.

The unanswered question is whether there is enough genetic diversity across the human species to cause intelligence to be significantly hereditable. The fear among scientists that try to keep the lid on this question is that the answer might be yes, and worse that such variations will correlate with geographic or national groupings. This would put a very nasty perceived scientific stamp of approval on racism (even though this would be unjustified), and could over time lead to discrimination and 'scientific racism'.

Anyway, in the end science will uncover the truth here, and in the meantime it is probably very prudent to not make any potentially inflammatory statements and to be very cautious about any studies that could fuel hate. I just find it absurd that whenever this kind of question comes up people start denying that there is any hereditary component of intelligence, and that IQ is completely meaningless, etc.

hazov5• 14 years ago

I just curious how you can support your point about squirrels, besides you falling prey of the bias of trying to advance an argument with a sole point.

For example, can these squirrels ancestors had better nutrition than the average squirrel, can we know about that just after seeing they mastering fire or wondering if they could learn calculus? I believe this type of question, the relation between nutrition and intelligence, can be answered much easily than searching for genes and looking for some desirable psychological trait in there, this can be easily tested in animals as well in a large couple of generations.

Either way I am not a biologist or even an psychologist so this is my take as a mathematician/statician. Also I'm not so confident science will ever come as close to explaining this completely.

justin_vanw4• 14 years ago

My point is that humans are much more intelligent than squirrels. Is this because of environment? Not at all, it is because we have the genetic programming to develop huge brains. The difference in intelligence between humans and squirrels is determined almost entirely by heredity.

The reason I point this out is that it is very common to see comments about heredity not being a factor in human intelligence. It may well be that heredity does not explain differences in intelligence between two humans, or it may be that heredity almost completely explains any differences in intelligence among humans. Science will eventually figure out the truth of the matter. However, heredity plays a very dominant role in determining intelligence, the only question is whether humans are all so genetically similar with regards to intelligence that environmental factors dominate genetic factors.

EDIT: The way I phrased the first paragraph sets up a false choice. Intelligence differences among humans could be hereditary, environmental, or most likely a complex combination of the two.

ralfn• 14 years ago

I love your example! Way out of my depth here, but i do have a question:

The squirrel obviously has a genetic trait that causes it to have a small brain. We can tell its iq just by looking at it, without considering its DNA. Would the same logic apply, when there is no visual/physical trait present?

Can one brain cell be dumber than another? Could they be wired in a less optimal way?

Genetics likely explain the difference between a retard and a functioning human, but csn they also explain the difference between an iq of 100 and an iq of 105?

When people have this debate about intelligence, the inevitable political argument is that maybe, we as a society could invest more in ourselves, our children and our neighbours children.

The relevant question, perhaps, should be: how much impact could "nurture" have? Is somebody with an iq of 120 physically limited to become smarter? Or is that person already in the range, where the genes were all good?

I dont think anybody doubts that a retarded person has a genetic disadvantage. But does the same apply to an average human being?

And if that limit exist, is it a personal limit, or one you share with most other humans on this planet?

uncomfytruths2• 14 years ago

You're not alone. I've always wondered, how come different dog breeds have different behavior and intelligence levels. Yet certain breeds are much smarter than others and capable of greater learning capacity. Any kind of comparison, even scientific, between human races would be seen as racist and thrown out immediately. It conjures up all sorts of negative emotions. Hitler, Nazis, Eugenics, Master Races, Holocausts.

I think deep down inside we are slaves to our genetics and many people know so and have significant evidence for it but are keeping quiet. And I don't blame them. The repercussions of telling the human race "Your success, happiness, intelligence, health, and entire life is limited by your genetics." would be horrific. Half the world would be on anti-depression medications if you told them that and proved it. No one wants to be told who they are before they're given a chance to discover themselves on their own. Also, genetics are not the end all of success. Just because someone doesn't have the genes that make them more likely to be successful doesn't mean they'll never be successful. There are other ways around. Aggression, luck, money, hard work, etc....

For instance, Ashkenazi Jews have the highest intelligence and very poor Spatial intelligence according to research. After them come north east Asians. Jews are disproportionately successful in numerous fields. 25% of Nobel prize winners are jewish and this is increasing. All of the major Hollywood studios were started by jews and are currently dominated by jews. The NYT's Joel Stein could only find 5 non-jewish executives in all of Hollywood. Most of the top writers are also jewish. Banking and finance is dominated by them as well. So is the fashion industry: Marc Jacobs, Ralph Lauren, Marc Echo, Calvin Klein, Estée Lauder, Kenneth Cole, and others are jewish. Levi's jeans as well. 2 of the internet's biggest companies, Google and Facebook were started by jews Larry Page, Sergey Brin, Mark Zuckerberg. People's refusal to acknowledge that genetics has anything to do with intelligence is exactly what has sprouted numerous conspiracy theories to try to explain why jews are so well achieved.

Also, look at men vs women. How many wars have women started compared to men? Nearly every war, genocide, and conflict has been caused entirely by men. Why is it that we never see the female versions of Hitler, Gangis Kahn, Napoleon, Stalin, etc... Because evolution has created extremely violent men (not all of us of course). Evolution wise, we're disposable. Women are not. The human race can easily be replenished with 99 women and 1 man. But not with 99 men and 1 women. And so women live much more "slow but steady" lifestyles while men are more likely to live "risky" lifestyles. Rewards are proportionate to risk. So men reap the rewards when it comes to inventions, companies, religions, nation building, etc...

nhoj• 14 years ago

"Half the world would be on anti-depression medications if you told them that and proved it."

So at least their unhappiness isn't limited by their genes?

malbertife• 14 years ago

"Also, look at men vs women. How many wars have women started compared to men? Nearly every war, genocide, and conflict has been caused entirely by men. Why is it that we never see the female versions of Hitler, Gangis Kahn, Napoleon, Stalin, etc... Because evolution has created extremely violent men (not all of us of course)."

One thing is to say that a war is unlikely to be started by a woman (your historical observation); another thing is to say that a woman is unlikely to start a war (your claim). That's because, historically, the people in a position to start a war have mostly been men.

If W means that a given leader (i.e., someone who could have started a war if he or she wanted to) was a woman and S means that the leader started a war, by Bayes' theorem the probability of the leader having started a war, given that she was a woman, is

P(S|W) = P(W|S) P(S) / P(W)

Likewise for men (if ~ means negation):

P(S|~W) = P(~W|S) P(S) / P(~W)

You observed that P(W|S) is much smaller than P(~W|S); but to compare P(S|W) and P(S|~W) you also need to take into account how much smaller P(W) is than P(~W).

Eliezer• 14 years ago

> Evolution wise, we're disposable. Women are not. The human race can easily be replenished with 99 women and 1 man. But not with 99 men and 1 women

This is not how evolution works. It runs on which genes outreproduce which other genes within a species, and cares nothing for "the good of the species" or "the survival of the species". If men are more violent, it was because individually more violent males outreproduced less violent males - not because "males are disposable". (Even this is still a simplification relative to inclusive genetic fitness, but it's definitely not because "males are disposable!")

http://wiki.lesswrong.com/wiki/Group_selection

nacker• 14 years ago

The horrific repercussions of loudly proclaiming the obvious are completely nullified by the near universal preference for comfortable illusions. Don't worry, be happy :)

DividesByZero5• 14 years ago

The squirrel example is absolutely absurd - there are clear physiological, morphological differences between human beings and squirrels that influence whether or not squirrels even have the capacity to master fire, or whatever other silly comparison you choose. Furthermore, I think you will find that environmental factors plainly influence the behavior of animal populations (squirrels, chimpanzees, birds - any kingdom, genus or species you choose) far more than any particular genetic variation among them - animals of the same species without abundant resources behave quite differently from animals of the same species in an environment of abundance (one need only look at any pest species - animal or plant - to see that this is true).

There does not exist much variation across 'societies' of animals within the same species - one tribe of baboons is much like another tribe - but there exist vast gaps between societies of human beings, so far as these gaps influence the environment of individuals among populations, and entire populations as a whole.

There is no physiological model for human intelligence, and since only physiological traits are inheritable (though psychological traits may be derived from morphological differences) there is no model for genetic influence on intelligence. Since there is no model, you can only blindly test a black-box hypothesis - and the results from those tests appear to support the conclusion that there does not exist any inheritable, physiological difference that would influence intelligence, controlling for societal factors.

DividesByZero5• 14 years ago

I would also add, that the political agenda is not from those advancing the idea that environment influences human development, but from those that contend it is genetics.

Consider the sorts of policies someone who wanted to maximise productivity in society would develop if it was found that genetics was a greater influencing factor - why would you support development for poor populations of people if it was found that they simply don't have the same development potential? You would simply screen for the 'genius' gene and push the rest of society toward a supporting role.

In the case of the environmental view, you must now implement policies that raise the living conditions for the majority of people in society - better and more schools, better and more social programs, better opportunity - that's expensive, and there's not much money to be made.

hazov5• 14 years ago

I don't think it's absurd, I only think initially that it was wishful thinking, now I see that it was only a poor example to a good idea that he explained later.

Yes intelligence has to do with heritability, there was initially an animal with had cognition (a word I much prefer instead of intelligence) this animal actually had descendants some of which are humans, we initially inherited this intelligence from him but also from other ancestors that developed this cognition latter as well.

You provided that we do not have a physiological model for intelligence, and I believe we will not have one for some decades at least if I'm to be optimist. That's a real large problem, another one is to relate this to genetics and environmental development, these would be a hard problem as far as I was told by some friends that are biologists.

Terretta• 14 years ago

> There is no physiological model for human intelligence...

No? I've read several. For example:

"The pronounced convolution of the human cortex may be a morphological substrate that supports some of our species’ most distinctive cognitive abilities. Therefore, individual intelligence within humans might be modulated by the degree of folding in certain cortical regions. We applied advanced methods to analyze cortical convolution at high spatial resolution and correlated those measurements with intelligence quotients. Within a large sample of healthy adult subjects (n = 65), we detected the most prominent correlations in the left medial hemisphere. More specifically, intelligence scores were positively associated with the degree of folding in the temporo-occipital lobe, particularly in the outermost section of the posterior cingulate gyrus (retrosplenial areas). Thus, this region might be an important contributor toward individual intelligence, either via modulating pathways to (pre)frontal regions or by serving as a location for the convergence of information."

http://cercor.oxfordjournals.org/content/18/9/2019.full

And:

When we examined the same regression model excluding ICV, some cortical measurements were associated with IQ frequently in frontal and temporal lobe. It might conclude that human intelligence is significantly correlated with the cortical complexity coming from brain size, rather than cortical shape itself. The combination of various cortical measurements explained 52.57% of IQ. The results showed that they were more useful for prediction of human intelligence than alone.

http://www.iaeng.org/publication/WCECS2011/WCECS2011_pp428-4...

I'm not defending these particular papers. I'm just baffled at the comment that there are "no" physiological models for intelligence.

The following paper appears to directly contradict your assertion that "there does not exist any inheritable, physiological difference that would influence intelligence":

"Variation in gray matter (GM) and white matter (WM) volume of the adult human brain is primarily genetically determined. Moreover, total brain volume is positively correlated with general intelligence, and both share a common genetic origin. However, although genetic effects on morphology of specific GM areas in the brain have been studied, the heritability of focal WM is unknown. Similarly, it is unresolved whether there is a common genetic origin of focal GM and WM structures with intelligence. We explored the genetic influence on focal GM and WM densities in magnetic resonance brain images of 54 monozygotic and 58 dizygotic twin pairs and 34 of their siblings. ... These findings point to a neural network that shares a common genetic origin with human intelligence."

http://www.jneurosci.org/content/26/40/10235.full

astrodust• 14 years ago

The performance of laboratory mice in mazes varies considerably among tested populations, with some mice clearly being "smarter" than others. It's possible to train a mouse to be smarter, to learn, but the effect is only a few standard deviations from the norm at best, not orders of magnitude smarter.

Remember that genetics is, at best, all about probabilities. Just because your parents are athletic is no guarantee that you're an athlete. There's always a one in four chance that you get the worst possible pairing of genes, after all.

Intelligence is a complicated thing. A child who can remember things easily will be considered very "smart" even if they can't do much with that information, whereas one who's very clever at figuring things out will be considered "stupid" if they aren't able to memorize as well.

IQ is such an arbitrary metric that it hardly deserves scientific consideration. It completely glosses over any unusual talents someone might have.

rokhayakebe• 14 years ago

We cannot engage into this kind of discourse until every party agrees on the definition of "intelligence," and whether intelligence is biological.

vibrunazo• 14 years ago

Am I the only one who reads these kinds reports and has that impression that today's psychology and biology is less than 0.1% of the way to provide a useful model for intelligence? The best measurement of intelligence that we have today (IQ tests) seem completely worthless for practical purpose compared to what we actually need to know to build solutions on. IQ tests are still too bad to measure actual "intelligence", as defined by our colloquial meaning and practical real-world potential. (as opposed to the official technical definition) Being able to measure people's intelligence would be extremely useful. IQ test results, not so much.

New findings about the impact of genetic vs environmental influences on IQ tests. Is about as useful finding new evidence about genetic vs environmental influences on people's ability to pass a "lick your elbow" test. Why should I care? It sure is interesting, and hey, anything "for science!". But, meh...

perlgeek• 14 years ago

But isn't it fascinating how much we can learn about intelligence even if we rely on crappy metrics like IQ tests?

Just like you can learn a lot about music without having a formal definition of what "good" music is.

monkeypizza• 14 years ago

How do you explain the fact that when the law allows, companies all over the world give IQ tests to prospective employees? And that studies have shown that IQ is one of the best predictors of job performance?

mangala• 14 years ago

Your first point would only elucidate a common misconception that IQ tests adequately measure intelligence. As to your second point, what studies are these? (I'd actually be interested)

obtu3• 14 years ago

IQ is one of those “look for the keys under the streetlight” things. It's for people who really care about intelligence being something measurable as a decimal number. In every study that isn't a meta-study like this one, the tasks that were measured are available and will tell more of the story.

Our minds are modular, studies measuring ability at precise tasks can improve our understanding of it. I wish people didn't try to make silly sweeping statements on nature vs nurture something that science has to care about.

The only justification for this paper is that it is debunking a book that was originally pseudoscience, but the whole discussion that followed that book is flawed for letting that book set the framing that intelligence boils down to one number.

EREFUNDO• 14 years ago

Studies have shown that the first 5 years of a child's life is when the brain develops the most. Proper nutrition and exposure to simple problem solving will significantly increase the chances of the child having a higher IQ.

Cyndre• 14 years ago

In my opinion the reason poorer people have less IQ then wealthier people, and also why adopted poor babys into middle class homes have higher IQ's comes down to what they spend their time thinking about. Poorer people spend their time worrying about food, money and basic needs. This occupys alot of their thought. Richer people don't need to worry about the basic needs and spend their time worrying about larger more complicated things.

ekianjo• 14 years ago

The title is misleading. This is not about intelligence, this is about IQ, and that's hardly the same thing. IQ has never been a reliable measure for anything, and something you can improve on by training/repeated exposure is certainly not linked to intelligence.

ramses• 14 years ago

Some people, and the referenced paper, are citing Jaeggi's dual n-back as evidence that interventions can positively affect g(F) (fluid intelligence).

I would like to mention that Jaeggi's results, and working memory training in general, have not been replicated.

The main issue with Jaeggi's experiment, is that proper controls were not used.

For a careful examination, and I would say thorough debunking of Jaeggi's results on dual n-back and g(F) improvement by training working memory, please read:

No Evidence of Intelligence Improvement After Working Memory Training: A Randomized, Placebo-Controlled Study. Redick, Thomas S.; Shipstead, Zach; Harrison, Tyler L.; Hicks, Kenny L.; Fried, David E.; Hambrick, David Z.; Kane, Michael J.; Engle, Randall W. Journal of Experimental Psychology: General, Jun 18 , 2012, No Pagination Specified. doi: 10.1037/a0029082

light3• 14 years ago

Nitpicking but this seems like a contradiction: "It is noteworthy, for example, that at a given level of IQ, Chinese have smaller frontal cortexes than Americans (Chee, Zheng, Goh, & Park, 2011), although Chinese brains as a whole may be larger than those of Americans (Rushton, 2010). Even with brain size equated between Chinese and Americans, the frontal cortex is larger in Americans (Chee et al., 2011)."

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