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.
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...
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!")
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).
So at least their unhappiness isn't limited by their genes?
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?
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.
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.
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.
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."
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.
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.
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.
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).
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.
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...
Just like you can learn a lot about music without having a formal definition of what "good" music is.
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.
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.
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.
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.
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.
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.
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.
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.
-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.
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?
"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.
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.
Would love to see some cites.
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.
Can we get a citation on this?
Although this need not be explained by genetics. It could just as easily be explained by culture.
http://harpending.humanevo.utah.edu/Documents/ashkiq.webpub....
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."
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?"
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.
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.
"In particular, there is clear evidence that school affects 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
http://www.diseaseproof.com/archives/healthy-pregnancy-does-...
Additionally, checkout the: http://www.omega3.org/
> 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.)
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.
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.
