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• Category: Science 
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Terence Tao is a 2006 recipient of the Fields Medal. He scored a 760 on the SAT-Math at the age of 8 and reportedly has an IQ exceeding 220. He is probably best known for proving the Green-Tao Theorem:

It is always possible to find, somewhere in the infinity of integers, a progression of prime numbers of equal spacing and any length.

I just came across this absorbing profile of Tao as a young boy. One impression that I take away from this piece is that Tao was blessed with good parents (in many senses).

• Category: Science • Tags: Human Biodiversity, IQ, Mathematics 
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Here is something that caught my eye over at PLoS ONE:

Most birds have simple genitalia; males lack external genitalia and females have simple vaginas. However, male waterfowl have a phallus whose length (1.5-40 cm) and morphological elaborations vary among species and are positively correlated with the frequency of forced extra-pair copulations among waterfowl species. Here we report morphological complexity in female genital morphology in waterfowl and describe variation vaginal morphology that is unprecedented in birds. This variation comprises two anatomical novelties: (i) dead end sacs, and (ii) clockwise coils. These vaginal structures appear to function to exclude the intromission of the counter-clockwise spiralling male phallus without female cooperation. A phylogenetically controlled comparative analysis of 16 waterfowl species shows that the degree of vaginal elaboration is positively correlated with phallus length, demonstrating that female morphological complexity has co-evolved with male phallus length. Intersexual selection is most likely responsible for the observed coevolution, although identifying the specific mechanism is difficult. Our results suggest that females have evolved a cryptic anatomical mechanism of choice in response to forced extra-pair copulations.

This paper has some interesting figures.

• Category: Science • Tags: Evolution 
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You can see it here. There are no surprises.

With two exceptions, each group shows a balanced profile in that it does no better or worse on Verbal than on Math, after each test has been normed relative to the entire test-taking population. The exceptions are males overall (who do about 30 points better on Math) and the group labeled “Asian, Asian American, or Pacific Islander” (about 70 points better on Math).

The rather large standard deviation of the Asian group suggests that it is in fact composed of two or more distributions. Regardless, the mean Verbal score for Asians is about 20 points lower than that for whites; the mean Math score is about 45 points higher. In fact, Math is too easy for some subgroup of Asians; a perfect 800 places an Asian only in the 98th percentile of his or her group.

The overall sex difference on Math is about 30 points in favor of males.

The white-black difference on the overall score is exactly 200 points. The Asian-black difference on Math alone is nearly 150 points.

• Category: Science • Tags: Human Biodiversity, IQ, Race, Sex Differences 
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Commentary has published an article by Charles Murray on a topic that has received much coverage here at GNXP: the high intelligence of Ashkenazi Jews (see also here, here, and here). He expands the historical and ethnic scope of the discussion in a very provocative way.

Update: Razib takes issue with Charles Murray on some points concerning historical Jewish accomplishment:

The first is the fully realized conceptualization of monotheism, expressed through one of the literary treasures of the world, the Hebrew Bible. It not only laid the foundation for three great religions but, as Thomas Cahill describes in The Gifts of the Jews (1998), introduced a way of looking at the meaning of human life and the nature of history that defines core elements of the modern sensibility. The second achievement is not often treated as a Jewish one but clearly is: Christian theology expressed through the New Testament, an accomplishment that has spilled into every aspect of Western civilization.

i am kind of confused by this (or more precisely, i think this is just wrong). we know who the church fathers who shaped christian theology were. to my knowledge, origen, athanasius, gregory of nazianzus, etc. were not christians of jewish origin. christian theology seems pretty clearly something for which the greek cultural matrix was necessary, and the prime driver. amongst the church fathers the theologians are even invariably greek speakers (latin speakers such as augustine can be considered an exception, but his work is wide ranging and not focused on theology like origen, for example). obviously the jews get some of the credit for being the source of the basic religious ideas, but, there were jews around while christian theology was being developed, but they were apart from it, and it seems that later judaism (e.g., the theology of maimonides) shows the same influence of greek philosophy after a period of acculturation.

as for the first, this is much more defensible. but, anyone who knows about the origin of judaism between the 10th and 2th centuries also knows that the influence of zoroastrian religious ideas were likely critical. so the issue is not as clear cut as charles would make it, though it is quite miraculous that an obscure people could produce a book like the hebrew bible which we cherish to this day.

Update II: Greg Cochran says:

Non-Ashkenazi Jews do not have high IQ scores today: see Lynn and David. Nor is there the slightest sign that that Jews were sharper than average in Classical times: not one single paragraph in preserved classical literature suggests that anyone had that impression. Nor did the Byzantines….

Genetic isolation is a precondition for this kind of selection and I can imagine that it happened in some Jewish group other than the Ashkenazi. The Iberian Jews, if anyone. The same is true for them having mostly urban occupations – it’s a precondition. But that shift hadn’t happened at all by Classical times – it began hundreds of years later and was only more-or-less complete by 800 AD. And only among the Ashkenazi was there a shift to (almost entirely) white-collar jobs. And the effects of any such selection among non-Ashkenazi Jews clearly no longer exist: look at the psychometrics and the occupation/educational pattern in Israel….

One other point: the mutations that look like boosters are mostly new (~1000 years old) as well as being confined to the Ashkenazim.

• Category: History, Science • Tags: Culture, History, Human Biodiversity, IQ 
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• Category: Science 
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Charles Murray has an important new paper in press at Intelligence. Here is the abstract:

The black-white difference in test scores for the three standardizations of the Woodcock-Johnson battery of cognitive tests is analyzed in terms of birth cohorts covering the years from 1920 through 1991. Among persons tested at ages 6-65, a narrowing of the difference occurred in overall IQ and in the two most highly g-loaded clusters in the Woodcock-Johnson, Gc and Gf. After controlling for standardization and interaction effects, the magnitude of these reductions is on the order of half a standard deviation from the high point among those born in the 1920s to the low point among those born in the last half of the 1960s and early 1970s. These reductions do not appear for IQ or Gc if the results are restricted to persons born from the mid-1940s onward. The results consistently point to a B-W difference that has increased slightly on all three measures for persons born after the 1960s. The evidence for a high B-W IQ difference among those born in the early part of the 20th century and a subsequent reduction is at odds with other evidence that the B-W IQ difference has remained unchanged. The end to the narrowing of the B-W IQ difference for persons born after the 1960s is consistent with almost all other data that have been analyzed by birth cohort.

What I find rather interesting is the evidence adduced for (1) a much larger IQ gap between blacks and whites (~1.5 standard deviations) in the early part of the twentieth century than has usually been claimed and (2) a subsequent narrowing of this gap to the familiar one standard deviation. However, for various reasons Murray admits that the evidence for this trend is “inconclusive.” A graphical display of the data analyzed by Murray is reproduced below.

The Flynn Effect has done much to convince differential psychologists that there are aspects of the relationship between latent constructs and their indicators that remain poorly understood, including perhaps the partition of within- and between-group phenotypic variance into genetic and environmental sources. However, hereditarians have long granted that certain environmental influences, not operating for the most part within the great bulk of white populations living in modern Western societies, may contribute to observed differences in test scores among racial groups. For example, Arthur Jensen (1998, pp. 495-498) found extremely convincing evidence for potent environmental effects on black IQs in a rural Georgia county where black SES was exceedingly low even relative to other blacks in the US. Older black sibs systematically scored worse on an IQ test than their younger sibs, indicating some environmental insult that accumulated over time. The overall black-white IQ difference of ~30 points in this county would have been reduced to the typical ~15 points if the decrement attributable to this cumulative environmental effect had been removed. Suppose that a much greater proportion of the American black population born earlier in the twentieth century suffered from whatever environmental deficits were responsible for the effects observed in this particular Georgia county. This is perhaps not an unreasonable assumption, given the concentration of the blacks in the rural South at the time. This would account for the trend displayed in the figure above.

I anticipate that more sophisticated psychometric analyses of these data will be forthcoming. In the meantime I have a question that perhaps Dr. Murray might be able to answer for us. In the first two samples, blacks show a larger variance in IQ. This goes against the grain of previous findings. Is this an artifact of the heterogeneity of scores across birth years within the black samples? What happens to the white:black variance ratio if age is held constant?

The paper is available in GNXP Forum.

• Category: Science • Tags: IQ, Race 
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Wendy Johnson, Thomas Bouchard, and their colleagues have an important paper in press at Intelligence reanalyzing data from the Minnesota Study of Twins Reared Apart (MISTRA). As many of you may be aware, the Minnesota group previously reported a correlation in IQ of 0.75 for 40+ pairs of identical twins reared apart (Bouchard et al., 1990). This implies a broad-sense heritability of 0.75; that is, three quarters of the variance in IQ is ascribable to genetic factors. MISTRA has continued since then, and this latest paper provides an update.

The sample used for this study included 126 twin pairs (74 monozygotic, 52 dizygotic) only. Most of the pairs were separated early in life, reared in adoptive families, and reunited only in adulthood. A few were separated early in life but reared by different biological family members. The twins were primarily from North America, Great Britain, and Australia, though several came from other countries and a few had been raised in different countries. They ranged in age from 18 to 79 years (mean = 42.7, SD = 13.6). Their educational backgrounds varied from less than high school to post-graduate experience, and occupations ranged accordingly.

These subjects were administered over 40 ability tests during their participation in MISTRA. In this reanalysis heritabilities were estimated for g in particular and also for lower-order factors such as verbal ability and image rotation. The heritability of g was estimated to be 0.77 (95% CI: 0.66-0.84). Estimated heritabilities for lower-order factors were also substantial.

The contribution to the correlation between twins caused by similarity in rearing environments was estimated by multiplying the square of the environment-score correlation by the correlation between twins in the environmental measure. It was found that the contributions to the correlation between twins in g by familial cohesion, expressiveness, conflict, independence, achievement orientation, intellectual-cultural orientation, active-recreational orientation, moral-religious emphasis, organization, and control (all dimensions of the Family Environmental Scale) were all zero to within two decimal places. The contributions by family size, parental occupation, parental education, and possessions in the home (including material, cultural, mechanical, and scientific possessions) ranged from zero to 0.02.

• Category: Science • Tags: General Intelligence, Genetics, IQ 
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In press at The Journal of Biosocial Science is a paper by Hanna David and Richard Lynn reviewing several Israeli studies comparing the IQs of the Ashkenazim to those of Jews from non-European backgrounds. A virtue of the paper is that it brings to light many studies that had originally been published in Hebrew and thus been obscured from the attention of Western differential psychologists.

The results, compiled over the last half century, are so stark that even as notorious a number bumbler as Lynn could not possibly have manufactured the signal. David and Lynn conclude that the Ashkenazim enjoy an IQ advantage of roughly 14 points over their fellow Jews.

Related: Recall that N-acetylaspartate (NAA), a brain metabolite found to correlate positively with IQ and often employed as a marker (by its absence) of brain insult or dysfunction, leads to Canavan disease when an individual is homozygous for a mutation knocking out the enzyme that breaks it down. This mutation is more common among the Ashkenazi Jews than in any other population–an observations that led Cochran, Hardy, and Harpending (2006) to hypothesize that the mutant is in fact an IQ booster. I have found an extremely thorough review of NAA by the neurochemist Morris Baslow (2003). Much of it is over my head, but perhaps the biochemists and neuroscientists among us can make something of it. My impression is that there are several plausible pathways by which NAA might affect the information-processing capacity of neurons and neural networks.

NAA is indeed an important intracellular osmolyte and storage form for brain Asp and Ac. It also participates in the formation of NAAG, supplies Ac to oligodendrocytes that may be incorporated into myelin, and has the potential for functioning as an intercellular signaling molecule, along with its derivative NAAG. However, as a hypothesis that encompasses most of these observations, it is proposed that the NAA cycle serves primarily as a neuronal mechanism to remove large amounts of metabolic water generated in performing its interneuronal and intercellular signaling tasks.

• Category: Science • Tags: IQ 
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In press at Intelligence, from the redoubtable Ian Deary and his colleagues:

There is scientific and popular dispute about whether there are sex differences in cognitive abilities and whether they are relevant to the proportions of men and women who attain high-level achievements, such as Nobel Prizes. A recent meta-analysis (Lynn, R., and Irwing, P. (2004). Sex differences on the progressive matrices: a meta-analysis. Intelligence, 32, 481-498.), which suggested that males have higher mean scores on the general factor in intelligence (g), proved especially contentious. Here we use a novel design, comparing 1292 pairs of opposite-sex siblings who participated in the US National Longitudinal Survey of Youth 1979 (NLSY1979). The mental test applied was the Armed Services Vocational Aptitude Battery (ASVAB), from which the briefer Armed Forces Qualification Test (AFQT) scores can also be derived. Males have only a marginal advantage in mean levels of g (less than 7% of a standard deviation) from the ASVAB and AFQT, but substantially greater variance. Among the top 2% AFQT scores, there were almost twice as many males as females. These differences could provide a partial basis for sex differences in intellectual eminence.

Related: Women and science, sex differences, Lawrence Summers.

• Category: Science 
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The release of Richard Dawkins’ new book The God Delusion (of which I have only read the first few pages) has returned my thoughts to the issue of what stance atheistic futurists such as myself should take toward the religious beliefs of our family members, friends, and fellow citizens between now and whatever singularities lie on the horizon. I have reached no definite conclusion on this point. I am torn between, on the one hand, (1) my devotion to the seeking of truth, and my revulsion toward the stupidities and barbarisms daily committed in the name of religion; and, on the other hand, (2) the innumerable small and quiet (and occasionally large and dramatic) ways in which faith is a force for good in the lives of people that I know. Perhaps this is all an illusion, but it seems to me that for many people religion is an irreplaceable inspiration to virtue, means of community, and source of solace in the face of barely endurable afflictions. When I read Dawkins on religion, no matter how right he is, no matter how devastating his blows, I get the sense of someone with a callous lack of understanding and sympathy for simple human frailty.

I thought this was an appropriate occassion to recall Anton Chekhov’s classic short story “The Student.” Perhaps I am wrong to see in it an acknowledgement of the importance of religious tradition (by an avowed atheist and anti-clericalist no less); to say what a Chekhov story is “about” is often to diminish it. But no matter. It is a wonderful story and worth reading in any case. The translation below is by Constance Garnett:

At first the weather was fine and still. The thrushes were calling, and in the swamps close by something alive droned pitifully with a sound like blowing into an empty bottle. A snipe flew by, and the shot aimed at it rang out with a gay, resounding note in the spring air. But when it began to get dark in the forest a cold, penetrating wind blew inappropriately from the east, and everything sank into silence. Needles of ice stretched across the pools, and it felt cheerless, remote, and lonely in the forest. There was a whiff of winter.

Ivan Velikopolsky, the son of a sacristan, and a student of the clerical academy, returning home from shooting, kept walking on the path by the water-logged meadows. His fingers were numb and his face was burning with the wind. It seemed to him that the cold that had suddenly come on had destroyed the order and harmony of things, that nature itself felt ill at ease, and that was why the evening darkness was falling more rapidly than usual. All around it was deserted and peculiarly gloomy. The only light was one gleaming in the widows’ gardens near the river; the village, over three miles away, and everything in the distance all round was plunged in the cold evening mist. The student remembered that, as he had left the house, his mother was sitting barefoot on the floor in the entryway, cleaning the samovar, while his father lay on the stove coughing; as it was Good Friday nothing had been cooked, and the student was terribly hungry. And now, shrinking from the cold, he thought that just such a wind had blown in the days of Rurik and in the time of Ivan the Terrible and Peter, and in their time there had been just the same desperate poverty and hunger, the same thatched roofs with holes in them, ignorance, misery, the same desolation around, the same darkness, the same feeling of oppression–all these had existed, did exist, and would exist, and the lapse of a thousand years would make life no better. And he did not want to go home.

The gardens were called the widows’ because they were kept by two widows, mother and daughter. A campfire was burning brightly with a crackling sound, throwing out light far around on the ploughed earth. The widow Vasilisa, a tall, fat old woman in a man’s coat, was standing by and looking thoughtfully into the fire; her daughter Lukerya, a little pockmarked woman with a stupid-looking face, was sitting on the ground, washing a cauldron and spoons. Apparently they had just had supper. There was a sound of men’s voices; it was the laborers watering their horses at the river.

“Here you have winter back again,” said the student, going up to the campfire. “Good evening.”

Vasilisa started, but at once recognized him and smiled cordially.

“I did not know you; God bless you,” she said. “You’ll be rich.”

They talked. Vasilisa, a woman of experience who had been in service with the gentry, first as a wet-nurse, afterwards as a children’s nurse expressed herself with refinement, and a soft, sedate smile never left her face; her daughter Lukerya, a village peasant woman who had been beaten by her husband, simply screwed up her eyes at the student and said nothing, and she had a strange expression like that of a deaf-mute.

“At just such a fire the Apostle Peter warmed himself,” said the student, stretching out his hands to the fire, “so it must have been cold then, too. Ah, what a terrible night it must have been, granny! An utterly dismal long night!”

He looked round at the darkness, shook his head abruptly and asked:

“No doubt you have heard the reading of the Twelve Apostles?”

“Yes, I have,” answered Vasilisa.

“If you remember, at the Last Supper Peter said to Jesus, ‘I am ready to go with Thee into darkness and unto death.’ And our Lord answered him thus: ‘I say unto thee, Peter, before the cock croweth thou wilt have denied Me thrice.’ After the supper Jesus went through the agony of death in the garden and prayed, and poor Peter was weary in spirit and faint, his eyelids were heavy and he could not struggle against sleep. He fell asleep. Then you heard how Judas the same night kissed Jesus and betrayed Him to His tormentors. They took Him bound to the high priest and beat Him, while Peter, exhausted, worn out with misery and alarm, hardly awake, you know, feeling that something awful was just going to happen on earth, followed behind. . .. He loved Jesus passionately, intensely, and now he saw from far off how He was beaten. . . . “

Lukerya left the spoons and fixed an immovable stare upon the student.

“They came to the high priest’s,” he went on; “they began to question Jesus, and meantime the laborers made a fire in the yard as it was cold, and warmed themselves. Peter, too, stood with them near the fire and warmed himself as I am doing. A woman, seeing him, said: ‘He was with Jesus, too’–that is as much as to say that he, too, should be taken to be questioned. And all the laborers that were standing near the fire must have looked sourly and suspiciously at him, because he was confused and said: ‘I don’t know Him.’ A little while after again someone recognized him as one of Jesus’ disciples and said: ‘Thou, too, art one of them,’ but again he denied it. And for the third time someone turned to him: ‘Why, did I not see thee with Him in the garden today?’ For the third time he denied it. And immediately after that time the cock crowed, and Peter, looking from afar off at Jesus, remembered the words He had said to him in the evening. . . . He remembered, he came to himself, went out of the yard and wept bitterly–bitterly. In the Gospel it is written: ‘He went out and wept bitterly.’ I imagine it: the still, still, dark, dark garden, and in the stillness, faintly audible, smothered sobbing.. . . .”

The student sighed and sank into thought. Still smiling, Vasilisa suddenly gave a gulp, big tears flowed freely down her cheeks, and she screened her face from the fire with her sleeve as though ashamed of her tears, and Lukerya, staring immovably at the student, flushed crimson, and her expression became strained and heavy like that of someone enduring intense pain.

The laborers came back from the
river, and one of them riding a horse was quite near, and the light from the fire quivered upon him. The student said good-night to the widows and went on. And again the darkness was about him and his fingers began to be numb. A cruel wind was blowing, winter really had come back and it did not feel as though Easter would be the day after tomorrow.

Now the student was thinking about Vasilisa: since she had shed tears all that had happened to Peter the night before the Crucifixion must have some relation to her. . . .

He looked round. The solitary light was still gleaming in the darkness and no figures could be seen near it now. The student thought again that if Vasilisa had shed tears, and her daughter had been troubled, it was evident that what he had just been telling them about, which had happened nineteen centuries ago, had a relation to the present–to both women, to the desolate village, to himself, to all people. The old woman had wept, not because he could tell the story touchingly, but because Peter was near to her, because her whole being was interested in what was passing in Peter’s soul.

And joy suddenly stirred in his soul, and he even stopped for a minute to take breath. “The past,” he thought, “is linked with the present by an unbroken chain of events flowing one out of another.” And it seemed to him that he had just seen both ends of that chain; that when he touched one end the other quivered.

When he crossed the river by the ferryboat and afterwards, mounting the hill, looked at his village and towards the west where the cold crimson sunset lay a narrow streak of light, he thought that truth and beauty which had guided human life there in the garden and in the yard of the high priest had continued without interruption to this day, and had evidently always been the chief thing in human life and in all earthly life, indeed; and the feeling of youth, health, vigor–he was only twenty-two–and the inexpressible sweet expectation of happiness, of unknown mysterious happiness, took possession of him little by little, and life seemed to him enchanting, marvellous, and full of lofty meaning.

• Category: Science 
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Classic Shaq quotes in no particular order, except that the leadoff quote is HBD-related … just to make this a true GNXP post …

Nobody wants to get dunked on by a white guy.

Tell Yao Ming I said this: “Ching-chong-yah-wah … ah-soooo …”
Yao Ming’s response:
Chinese is a hard language.

Some things you just can’t question. Like you can’t question why two plus two is four. So don’t question it, don’t try to look it up. I don’t know who made it, all I know is it was put in my head that two plus two is four. So certain things happen. Why does it rain? Why am I so sexy? I don’t know.

After winning the state high school basketball championship:
REPORTER: Shaquille, what do you attribute your team’s success to?
SHAQ: I attribute it to me.

I’m like the Pythagorean Theorem. Not too many people know the answer to my game.

One time I put up 40, 50 points dunking on Shawn Bradley. After the game he brought his family over. He was like, “This is my wife. She wants to take a picture.” I’m like, “Nice to meet you.” I smile into the camera, take the picture, and then feel guilty about dunking on him so many times.

I knew I was dog meat. Luckily, I’m the high-priced dog meat that everybody wants. I’m the good-quality dog meat.

Pat Riley is a good-looking man. It’s my job to keep him looking good.

Rolling down the window of his SUV while driving through South Central and shouting at the top of his lungs:

The Spurs? They’re a good WNBA team.

I am Superman. And the only thing that can kill Superman is Kryptonite. And Kryptonite doesn’t exist.

Y’all reporters like my quotes, don’t you? Yeah. My quotes are Shaqalicious.

Me shooting 40% at the foul line is just God’s way to say nobody’s perfect.

After a 25-point comeback victory against the Boston Celtics:
They shot the ball well early. What comes out of the microwave hot doesn’t always stay hot. I know, because I eat bagels in the morning.

I had an awful first quarter but I picked it up. To all you single guys out there, it’s not how you start the date, it’s how you finish it, sir. A lot of people can, you know, start the date with flowers and candy, but if you don’t finish the date … you know what I mean?

When asked how he would defend himself:
I wouldn’t. I would just go home. I’d fake an injury or something.

When describing his MBA classmates’ reaction to him:
“They would all say, ‘You’re not like we thought you would be. You’re not as smart as we thought that you would be.’”

When asked to compare Penny Hardaway, Kobe Bryant, and Dwayne Wade:
The difference between those three is the Godfather trilogy. One is Fredo, who was never ready for me to hand it over to him. One is Sonny, who will do whatever it takes to be the man, and one is Michael, who if you watch the trilogy, the Godfather hands it over to Michael. So I have no problem handing it over to Dwyane.

I’m like Pampers, toothpaste, and toilet paper. I’m proven. To be good. And useful.

On returning from a trip to Europe:
REPORTER: Shaq, did you visit the Parthenon?
SHAQ: I don’t know. I can’t really remember the names of the clubs that we went to.

They call me the Big Sewer because I have a lot of shit in my game.

When asked whether the Sacramento Kings might dethrone the Lakers:
I’m not too worried about the Sacramento Queens.

I’m tired of hearing about money, money, money, money, money. I just want to play the game, drink Pepsi, wear Reebok.

Utah had beaten us in the playoffs the year before, and my knee was screwed up, so Greg Ostertag was scoring, blocking a couple of my shots. I guess it gave him confidence. Lord knows, after seeing his game, he needs it. I went to talk to him after a practice and let him know he needs to just play and not talk. I said, “Man, you need to watch what you say,” And he was like, “Fuck you, watch what you say.” So I was like, “Oh, you bad now?” I wasn’t even mad, it was like a reflex. My openhanded right came up and smacked him upside his crewcut head. He went down, fetal position, whining, “My contact lenses, my contact lenses!” If Ostertag had known I’d taken Tae-Bo with Billy Blanks, he wouldn’t have said that.

On why Phil Jackson assigned him to read Thus Spake Zarathustra:
Nietzsche was a difficult book to read. Nietzsche was so unique, they thought he was crazy. I guess Phil thinks I’m very unique to a point where I may be crazy.

When asked about his relationship with Kobe Bryant:
I’m a married man. A married man doesn’t want to have a relationship with another man. So stop asking me about it … OKAY?

On his physical conditioning:
My weight numbers, sometimes it’s going to be a higher number, and you mere Earthlings, when you hear a high number, you’re automatically going to think it’s fat because you’re only of this planet. But no, I’m just a big, sexy, beautiful man that’s up in the 340s, 350s.

• Category: Science 
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The LA Times just ran two article about genetic engineering (here and here). I can’t guarantee that these articles are free of “idiotic mistakes” of the kind that drive Greg Cochran nuts, but I thought they were interesting. A money quote:

Gene therapy is making a comeback after a series of serious setbacks that threatened to permanently derail human tests. In recent years, European scientists have cured more than two dozen patients suffering from three rare, and in some cases lethal, immune disorders.

Spurred by this success, plus the development of new techniques aimed at making the therapy safer and more effective, more than 300 gene therapy trials, including the one for Parkinson’s at UC San Francisco, are underway in the U.S. and abroad.

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A few months ago Agnostic alerted us to an issue of PLoS Medicine devoted to skeptical appraisal of “disease mongering.” In this issue the psychiatrist David Healy claimed that the evidence supporting the efficacy of medications commonly prescribed for the prophylactic treatment of bipolar disorder is either weak or nil.

As bipolar disorder is the most painful and debilitating non-terminal disease that I have witnessed so far during my brief time on earth (although mild forms may be conducive to creativity), I was sufficiently provoked by this claim to take a look at the literature in this area. In this post I give a brief report of what I have found. Please note that I have no particular expertise in neurochemistry, pharmacology, or psychiatry, and in any case I make no warrant for the comprehensiveness of this post. The findings in this field are unfortunately quite confusing and contradictory; authorities going over the same evidence sometimes come to opposite conclusions in their reviews, and there is no particular reason to trust my arbitration of this matter. So read at your own risk. However, I think this post is worthwhile if it reminds us that an incidental benefit of the pursuit of knowledge is the alleviation of human suffering. (Note: I personally believe that this is true of all knowledge, including the “forbidden” knowledge deemed by the skeptics of GNXP’s more controversial posts to be wicked and irresponsible.) As always, of course, I welcome criticism and pointers from informed readers.

Related: Psychotic mania in bipolar disorder resembles schizophrenia in many respects; common symptoms include hallucinations (primarily auditory), delusions, disordered thinking, and loss of contact with reality. Moreover, a curious risk factor that the two diseases share in common is a seasonality effect; sufferers from bipolar disorder show an excess of winter/spring births. Greg Cochran and his colleages have written two papers that I know of addressing the likely infectious causation of schizophrenia (Cochran et al., 2000; Ledgerwood et al., 2003). Much of their arguments, including evolutionary considerations, are just as applicable to bipolar disorder. I hope that work on pathogenic hypotheses will become a top priority for bipolar-disorder researchers.

My impression is that valproic acid (also known as divalproex and by its trade name Depakote) is rapidly becoming the preferred treatment for bipolar disorder. Its reputation among clinicians is growing as a result of their experience with patients, and its undesirable side effects are demonstrably less numerous and severe than those of lithium.

Although there exist at present fairly detailed mechanistic hypotheses regarding how valproic acid, lithium, and other drugs might dampen epilepsy and the mood oscillations characteristic of bipolar disorder, my fallible impression is that none of these commands anything approaching a consensus that it is the correct explanation. In fact, I suppose that physicists and other real scientists would complain that explanations on the table regarding the mechanistic action of all mood-affecting drugs are rather handwavy. This uncertainty in our knowledge severely limits the kinds of inferences that can be made. For example, if the efficacy of a drug in treating symptoms at the height of their acuity is securely established, can we generalize this to its effectiveness as a prophylactic? It is hard to say without a more detailed model of the disease etiology and the mechanistic action of the drug. And so we resort to statistical black-box evidence.

There are actually two things that are wanted from valproic acid or any treatment for bipolar disorder: (1) efficacy in treating patients displaying acute symptoms; and (2) efficacy as a prophylactic treatment preventing the occurrence of future episodes. The evidence that valproic acid does in fact accomplish (1) looks fairly good to me. Many studies have found valproic acid to be effective in diminishing the symptoms of acute mania, and it is on the basis of these studies that the FDA has approved valproic acid for this use. The most-cited of these studies that I have found is by Bowden et al. (1994). The abstract:

OBJECTIVE–To compare the effectiveness of divalproex sodium with that of lithium and placebo in patients with acute mania. DESIGN–Randomized, double-blind, parallel-group study of treatment outcomes in patients with manic-depressive illness…. RESULTS–Intent-to-treat analysis for efficacy was based on data from 68, 35, and 73 patients in the divalproex, lithium, and placebo groups, respectively. Groups were initially comparable except that all eight patients with four or more manic episodes in the previous year were in the divalproex group. In 30%, 33%, and 51% of the above groups, treatment was prematurely terminated due to lack of efficacy, with fewer premature terminations from divalproex than placebo (P = .017). The proportions of patients improving at least 50% were higher for divalproex and lithium groups than for the placebo group: 48% for divalproex (P = .004) and 49% for lithium (P = .025) vs 25% for placebo. Divalproex was as effective in rapid-cycling manic patients as in other patients. CONCLUSIONS–Both divalproex and lithium were significantly more effective than placebo in reducing the symptoms of acute mania. The efficacy of divalproex appears to be independent of prior responsiveness to lithium.

For references to more studies in this vein, the interested reader may consult Torrey and Knable (2002), an accessible guidebook aimed at non-academics. In fact, Torrey and Knable is a good background source for everything covered in this post; its descriptions of relevant studies are telegraphic but fair. (Incidentally, Fuller Torrey was an early adopter of pathogenic causation of mental illness.)

Now, the evidence that valproic acid works as a prophylactic is considerably more iffy. The gold standard for multi-center, placebo-controlleded, double-blind, randomized studies in this regard is Bowden et al. (2000), and its results on balance favor the effectiveness of valproic acid but are still somewhat ambiguous.

If we look at just the raw percentages of patients terminated from the one-year trial phase of the study within each treatment group, we seem to have some clear evidence that divalproex is superior to placebo. The percentage of patients on divalproex removed from the trial phase for depressive symptoms severe enough to warrant hospitalization (or for severe bipolar symptoms of any kind) was significantly smaller than the percentage of patients on placebo removed for the same reasons. However, it turns out that the sheer number or percentage of patients removed from a treatment group because of bipolar symptoms was not the a priori primary outcome measure. Rather, the authors employed the time elapsed until the occurrence of a bipolar episode (i.e., any episode severe enough to warrant treatment discontinuation or the prescribing of antidepressants). It i
s not clear to me why the latter outcome should be preferred over the former rather than both being seen as complementary, but apparently such is the convention in this research community. Now, none of the differences in “survival times” among the treatment groups were significant at the Bonferroni-corrected 0.05 level given the large confidence interval of this statistic. On the other hand, the numbers strike me as noticeably tending toward the expected direction. For example, the longer time to development of any bipolar episode by the divalproex group relative to placebo was marginally significant (p < 0.06). Also,

[a]mong patients taking divalproex at the end of the open phase, those randomized to divalproex had a 46% longer duration of prophylaxis in the maintenance phase (p = 0.03) than those randomized to placebo; they were also 42% less likely to be prematurely dropped from the study for any major affective episode (p = 0.04) and 32% less likely to be prematurely terminated for any reason (p = 0.002).

I gather that the hypotheses tested in the above quote were not formulated a priori but were a result of post hoc trawling through the data. For this reason we should be suspicious of the results. But if taken at face value, they suggest that the patients deemed by their doctors to be suited best for divalproex as a treatment for acute mania during the open phase (and in fact treated successfully for acute mania during the open phase with divalproex) were biased toward responding favorably to divalproex as a prophylaxis during the trial phase. This strikes me as an eminently reasonable explanation and should be tested in future studies. In a later follow-up, the authors present results of more post hoc analyses of these data with a focus on depressive symptoms (Gyulai et al., 2003). The results are promising, although again they should be taken with a grain of salt.

The overall marginality of the primary outcome measures may well be an artifact of the stringent criteria that patients had to meet before they could be randomized into the trial phase (full recovery from the index manic episode, two consecutive GAS score of 60+, etc.). These requirements were initially thought to make for a cleaner experiment, but in hindsight they may have unduly compromised its power by biasing the intent-to-treat sample toward patients predisposed to good outcomes. On the basis of previous studies the authors expected over half of the placebo patients relapse into mania, but only 22% actually did so. It is of course fortunate that the majority of the patients on placebo experienced such favorable outcomes, but strictly for purposes of the study the wellness of the placebo group is undesirable in that it may have created too high a baseline; if everyone is going to do relatively well anyway, then there is little room for a treatment drug to give a boost.

Another surprising result of the study was the relatively weak performance of lithium on a number of indices. But these indices suffered from the power problem noted above, especially because lithium was not the primary study drug and thus had a smaller treatment group than divalproex. As far as I can tell, these findings are atypical and not accepted as disproving the efficacy of lithium as a prophylactic treatment. See Muzina and Calabrese (2005) for a review of older studies supporting the effectiveness of lithium prophylaxis and also two recent placebo-controlled, double-blind, randomized studies conducted over a longer time period that found patients on lithium faring significantly better than those on placebo with respect to both manic and depressive symptoms.

The atypical (or second-generation) antipsychotics are also rising in popularity because of the mildness of their side effects relative to typical (or first-generation) antipsychotics. My subjective impression is that olanzapine (also known by its trade name Zyprexa) is becoming the atypical antipsychotic of choice. It has also, as far as I know, the only antipsychotic subjected to a placebo-controlled, double-blind, randomized study of its efficacy as a prophylactic (Tohen et al., 2006). Fortunately, the results of this study are much more clear-cut than those of the similar study of valproic acid–perhaps because this time the authors included in the intent-to-treat sample only those patients who had responded well to the study drug (olanzapine) during the open phase. From the abstract:

Time to symptomatic relapse into any mood episode was significantly longer among patients receiving olanzapine (a median of 174 days, compared with a median of 22 days in patients receiving placebo). Times to symptomatic relapse into manic, depressive, and mixed episodes were all significantly longer among patients receiving olanzapine than among patients receiving placebo. The relapse rate was significantly lower in the olanzapine group (46.7%) than in the placebo group (80.1%).

See also Perlis et al. (2006) for a quantitative meta-analysis demonstrating the efficacy of atypical antipsychotics in the treatment of acute mania.

For the most part I will not discuss the undesirable side effects of these drugs, although they must certainly be given some weight in any decision as to whether they should be prescribed. The one side effect that I will briefly comment on is the risk of suicide. In his commentary Healy present a compelling analysis in favor of the contrarian conclusion that prophylactic treatment for bipolar disorder actually increases the probability of suicide. I have found one quantitative meta-analysis of the antisuicidal effect of lithium that is contra Healy (Tondo, Hennen & Baldessarini, 2001):

METHOD: Broad searching yielded 22 studies providing suicide rates during lithium maintenance; 13 also provide rates without such treatment. Study quality was scored, between-study variance tested, and suicide rates on vs. off lithium examined by meta-analyses using random-effects regression methods to model risk ratios.
RESULTS: Among 5647 patients (33 473 patient-years of risk) in 22 studies, suicide was 82% less frequent during lithium-treatment (0.159 vs. 0.875 deaths/100 patient-years). The computed risk-ratio in studies with rates on/off lithium was 8.85 (95% CI, 4.1-19.1; P

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Scrawled on the wall of a toilet stall in my local math department:

(integral from 10 to 13)(2xdx) = what I did with your mom last night!

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Some of you may have read the recent news report of a paper by William Flynn and James Flynn arguing that the white-black IQ gap has steadily narrowed over the last 30 years. I believe that this paper, as well as a rebuttal by Phillipe Rushton and Arthur Jensen, will be published in an upcoming issue of Psychological Science.

Our own resident educational psychologist Alex Beajuean is analyzing these and other relevant data using a model-based approach that is more sophisticated than the techniques used by Dickens and Flynn. We may deliver a report here at GNXP when this analysis is done. In the meantime, we have made a little graph showing the results of the studies conducted during the period covered by Dickens and Flynn, including those studies that Dickens and Flynn omitted from their analysis (and that Rushton and Jensen argue should have been included):

As you can see, the gap between white and black children does indeed seem to be decreasing over time. The gap between adults, however, does not show any noticeable trend. Perhaps the adults are lagging behind a true gain by blacks as a whole, but remember also that the correlation between genotypic and phenotypic IQ increases with age. Without further analysis, I suggest simply keeping this graph in mind as we go forward.

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I have just reread the epic book chapter “Physical Correlates of Human Intelligence” by Arthur Jensen and S.N. Sinha. This is still a gold mine of theoretical insight and empirical findings, documenting among other matters (1) cross-assortative mating as the likely cause of the correlation between IQ and height, (2) the correlation between IQ and head size with body size partialed out, (3) the differences in brain weight upon autopsy between blacks and whites, and (4) much, much more.

Included in the “much, much more” is a passage concerning serum uric acid that somehow failed to capture my attention the first time that I read this chapter and that I now think is worth summarizing here. As you will see, I think that beneficial applications can come out of exactly these kinds of findings from biologically oriented behavioral sciences. I hit up Google Scholar and Pubmed for “serum uric acid” and got nothing recent pertaining to its behavioral correlates, so I assume that the review by Jensen and Sinhan (1994) is still adequate. (Perhaps sharper-eyed readers can help us out here.)

A belief in an association betweeng gout and eminence supposedly goes to back to antiquity. The British psychologist Havelock Ellis (1904) was the first to provide formal evidence of this association when he found a much higher incidence of gout in a sample of intellectually eminent Britishers than in the population at large.

Gout results form inflammation as a result of uric acid crystals forming in a joint. Uric acid is excreted in urine and carred in low concentrations in the blood as serum uric acid (SRA). At higher concentrations SUA forms the crystals deposited in the joints that lead to gout. In all mammals except Homo sapiens and the other great apes, uric acid is not the end product of its pathway; in the other mammals the enyzme uricase oxidizes uric acid to allantoin, which is excreted as the end product of this metabolic chain. Presumably, the great apes fixed a loss of function that prevents uricase from doing its work and leaves uric acid as the end product of purine metabolism. The molecular structure of uric acid is highly similar to that of caffeine, which as we all know is a central nervous system stimulant. Parent-offspring regressions indicate a narrow-sense heritability of SUA level between 0.30 and 0.40.

The hypothesis that SUA is an endogenous stimulant somehow related to the mental capacities of great apes stimulated hundreds of studies. What follows is a summary of this research.

  • SUA levels and retarded/nonretarded show a significant point-biserial correlation. Also, groups with above-average IQ (Ph.D. students, med students, business executives) show higher levels of SUA. The overall correlation between SUA and IQ is rather small, however, averaging about 0.085 over several studies with a combined N in the thousands.
  • It appears that the SUA exerts its chief causal influences on achievement per se rather than sheer ability, as if SUA acted as a drive-inducing cortical stimulant. In a study of 149 male high school students, SUA level was most notably correlated with the residual of the regression of GPA on IQ. SUA level was also correlated with number of extracurricular activities. In another study SUA showed a significant point-biserial correlation with “school dropout/persistance in school” as well as correlations with “need for achievement.”
  • When 144 university professors were rated on overall level of achievement, the ratings were correlated 0.50 with SUA level. Among nontenured faculty, number of publications was correlated 0.37 with SUA level.
  • Several studies have found that SUA level is correlated with upward social mobility, although apparently one large study is contra.
  • One large study (N = 1500) found higher SUA levels in professionals and executives than in farmers and unskilled workers.

Given the great promise of these findings, I’m somewhat puzzled that there has not been more recent follow-up of this area. Why not manipulate SUA levels experimentally to determine which way the causal arrow point in these correlations? Which, of course, leads naturally to this: if SUA does indeed have some causal effect on achievement drive and motivation, why not develop a form that humans can self-administer?

Feeling low on inspiration for papers and the tenure clock is running? Inject some SUA into your ass and boom! 73 papers belted out in one year. Feel like the dumbest person at the conference and you have to give your talk after the next break? Instead of going over your Powerpoint slides again, just slip into the bathroom, get out the syringe … and come out ready to blow everyone away!

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The journal Evolutionary Psychology is completely open access. It is probably worthwhile to check in there periodically. A just-published original research article, “Do some taxa have better domain-general cognition than others? A meta-analysis of nonhuman primate studies,” is getting some press coverage.

It seems to me this journal contains a fair deal of book reviews and editorials. Geoffrey Miller has a piece called “The Asian future of evolutionary psychology” that I find extremely dubious, even for a forum where speculations only loosely moored to any empirical findings are clearly invited. My take on Miller as a sensationalist who cares more about leaving vivid impressions than seeking the truth is confirmed to my satisfaction.

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Here is another interesting new paper in PNAS. The abstract:

The most consistent biodemographic correlate of sexual orientation in men is the number of older brothers (fraternal birth order). The mechanism underlying this effect remains unknown. In this article, I provide a direct test pitting prenatal against postnatal (e.g., social/rearing) mechanisms. Four samples of homosexual and heterosexual men (total n = 944), including one sample of men raised in nonbiological and blended families (e.g., raised with half- or step-siblings or as adoptees) were studied. Only biological older brothers, and not any other sibling characteristic, including nonbiological older brothers, predicted men’s sexual orientation, regardless of the amount of time reared with these siblings. These results strongly suggest a prenatal origin to the fraternal birth-order effect.

The same issue has a commentary that reviews the research in this area. The authors propose a mechanism summarized in their Figure 1:

A mother carrying a first son has very little exposure to the proteins he is making because of the placental barrier. But upon delivery and the inevitable mixing of fetal and maternal blood, her immune system will now see proteins it has never seen before, including proteins encoded on her son’s Y chromosome. If she mounts an immune response to these proteins, then any subsequent sons will be exposed, via active transport across the placenta, to maternal antibodies directed against the male-specific proteins. These maternal antibodies might then perturb development of the younger son, decreasing birth weight and affecting his brain to increase the probability that he will grow up to be gay. Whether this is what is really happening for sexual orientation remains to be seen, but it is a provocative hypothesis.

I leave it to others to evaluate this specific result and the broader hypothesis in mechanistic and evolutionary terms. (One thought of mine: a potential mechanism more generally for greater male variability in all traits? An easily testable hypothesis.) As I read them, these papers are not in conflict with Greg Cochran’s germ theory of homosexuality.

Coffee Mug Addendum: There is a colorfully written commentary in Endocrinology for free that sums up some of the research into neurobiological and endocrinological mechanisms determining sexual preference. Sheep seem to be a good model system for this issue, and the above papers imply some fairly explicit predictions about birth-order effects in homosexual sheep.

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Here is an interesting new paper in PNAS. You can read a news article about it here.

In a typically insightful piece, the underground statistician La Griffe du Lion estimates that South and East (Chinese, Japanese, Korean) Asians average an SAT-M score of ~630-640. This implies that the average East/South Asian student obtains a higher score on the SAT-M than 85-90 percent of SAT takers at large. When I first came across this figure I could scarcely believe it, but since then it has come to my attention that the modal SAT-M score by far among East Asian students at elite universities is 800. This huge pile-up of scores at the ceiling is readily explained if 800 is in fact only ~1.5 sigmas from the East Asian mean. What might account for this whopping disparity? The writer of the linked-to article seems to think that this recent brain-imaging study has some bearing on this question:

And cognitive scientist Michael Posner of the University of Imbler thinks the study could contain a message relevant to the teaching of math. Could a different strategy for processing numbers help explain why Chinese students seem to do better at math than English-speaking students do? “It could very well be,” he says.

Let us see where this study takes us. I would say not very far, but it raises some interesting thoughts.

Ten native Chinese speakers (of Chinese ethnicity) and ten native English speakers (white) were put through four different tasks while their brains were scanned by fMRI: (1) Symbol, deciding whether the third figure in a triplet of figural stimuli is presented in the same orientation as the previous two; (2) Number, same as Symbol except the stimuli are numbers rather than non-semantic figures; (3) Addition, deciding whether the third number is equal to the sum of the first two; and (4) Comparison, deciding whether the third number is larger than both of the first two. The control task consisted of deciding whether the third dot in a triplet of dots was the same color as the previous two. All subjects were comparable in age and of the same handedness. There does not seem to have been any attempt to control for IQ or, probably more importantly, narrow ability factors. I would insert a slick figure of brains lighting up at this point, but as Blogger is acting up again I will settle for, um, a verbal representation instead (this will seem like a bad joke later).

While the Symbol condition evoked no differences of note between groups, significant
differences emerged in the other three.

The activation in NES [native English speakers] is greater in the left SMA [supplementary motor area], Broca area, and Wernicke area (Wn) [the so-called "language centers"], compared with the corresponding areas in NCS [native Chinese speakers]…. Importantly, much larger brain activation was found at a region in-between BA6, BA8, and BA9 in NCS. We termed this region as a premotor assocation area (PMA), which has previously been associated with visuo-spatial processing …

Interestingly, within-group comparisons also reveal a similar activation pattern between Symbol and Number conditions in NCS…. Such similarity may imply the utilization of a visual-symbol system for representing Arabic digits in Chinese speakers….

For the other three conditions [Number, Addition, Comparison], although similar activated networks were found in the occipito-parietal areas, perisylvian area, and PMA area, the perisylvian activations were significantly larger in NES than those in NCS….

The larger perisylvian activation in NES alone may suggest that the brain representation of numbers is influenced by different language processes. However, across all of the four conditions as the arithmetic loading increased, there was a trend of increase in the premotor activation in NCS but not in NES. Such a trend was also found at the perisylvian area in NES but not in NCS. Therefore, between NCS
and NES, there was a double dissociation in the brain activation during these tasks, which suggests that the differences may not be merely due to different languages but also due to specific mathematic processes. In other words, whereas the numbers are represented in different brain regions from those involved in languages, people
speaking Chinese or English may engage different neural pathways in numerical processing.

I am reminded of an amusing passage from The Pleasure of Finding Things Out where the physicist Richard Feynman describes his informal experiments with counting silently in one’s head. He found out that it is possible to count in two different ways: (1) Feynman himself seemed to say the numbers “one, two, three,” and so on to himself, sotto voce as it were; while (2) his friend, the statistican John Tukey, visualized a mental number line and moved along it tick by tick. It has indeed been found in more recent studies that even stimuli in “elementary” cognitive tasks can be represented in different ways by different individuals (e.g., verbal/propositional v. spatial/figural).

So it seems that the present study has revealed another such difference scaled up to the level of group averages. The authors speculate that “the strong involvement of visuo-premotor association in NCS may be related to the experience of reading Chinese characters…. The use of the abacus in many Asian schools also suggests that, in one way or the other, the engagement of a ‘mental image’ for arithmetic could be related to the differences in brain activation.” Hmm. Well, maybe so. The logical next step then is to scan the brains of English speakers of Chinese ethnicity, preferably with both a larger sample and a larger control group. It should be possible to find Chinese Americans who do not read or speak Chinese. It is also desirable to ensure that the present findings are not an artifact of an ability difference between the two groups. As I pointed out earlier, no effort was made to match the groups on ability levels and profile. A pseudo-race group of white English speakers with an ability profile similar to that of typical East Asians (average SAT-V scores, high SAT-M scores, high spatial scores) should be compared to a more typical group of whites; if differences in brain activation between the typical whites and the pseudo-Asians are similar to those in the present study, then the difference is not a
true race- or culture-specific difference but rather a mere ability difference. In the latter case, of course, we would still want to know what causes the elevated spatial and mathematical abilities of East Asians in the first place.

Can the extant literature give us any hints as to such a follow-up would turn out? Check out p. 169 of Nicholas Mackintosh’s textbook IQ and Human Intelligence, which provides mean WISC-R subtest scores of the Japanese standardization sample. (The content of these subtests is described here.) The subtests can be classified as follows by performance of the Japanese relative to whites:

much better than whites: Block Design
better than whites: Arithmetic, Digit Span, Picture Completion, Picture Arrangement, Object Assembly
comparable to whites: Similarities, Digit Symbol />worse than whites: Information, Comprehension

It is clear that Japanese children excel their white peers in mental tests that do not load on the verbal factor. This may be due to an advantage in g, but the Japanese-white gap on Block Design is so large that at this impressionistic level I am inclined to invoke a Japanese advantage in the spatial-visualization factor as well. It is tempting to speculate that perhaps East Asians preferentially employ some form of analogical representation of numbers precisely because of this advantage.

Regardless of its bearing on the processing of number, is the profile difference between whites and East Asians genetic or cultural? I know of one adoption study of East Asian mental abilities that has employed the WISC-R (Frydman & Lynn, 1989). After a correction for the Flynn Effect it was found that 19 Korean orphans, adopted into Belgian families between the ages of 3 to 72 months and tested at an average age of 10 years, obtained an average IQ 10 points higher than the Belgian population mean (p < 0.01). Here are the mean subtest scores of this group, apparently uncorrected for secular trends:

Block Design: 13.89
Picture Arrangement: 13.32
Object Assembly: 13.26
Picture Completion: 13.00
Similarities: 12.95
Arithmetic: 12.79
Coding: 12.58
Comprehension: 12.00
Information: 10.37
Vocabulary: 9.63

Although these means are probably inflated upward, it is still easy to see that the relative performance profile of the Korean adoptees raised in Belgium and tested on the French translation of the WISC-R is unmistakably similar to that of native Japanese children tested on the Japanese translation. The nature of white-East Asian differences in mental abilities appears to much more complex than that of white-black differences, as the former likely involve large and small differences on several factors. It is true generally that all pairwise population comparisons other than white-black have received not nearly enough psychometric research effort as they deserve. But even without a more precise psychometric characteriziation, the evidence here still quite obviously suggests that the typical East Asian profile (high spatial, weak verbal) follows East Asian children regardless of the culture in which they are reared.

In an interesting study, David Geary and his colleagues found no substantial differentiation in arithmetical abilities between older cohorts of Americans and Chinese and thus argued that the observed differences today between whites and East Asians in arithmetical skill (and perhaps higher-level mathematical abilities) is the result of the declining quality of American education and resulting underperformance of Americans relative to their potential. I am not sure what to make of this. It may be that the results for the older cohorts can be explained as part of the same secular trend for East Asians over time observed in the data collated by Lynn (and made available in GNXP Forum), a kind of staggering of the Flynn Effect. Moreover, the difference favoring Americans on spatial tasks loading on the same factor defined by Block Design is decidedly out of line with the results of other studies. Something atypical may have been going on here. Still, we should keep this study in mind going forward.

A perhaps more informative design is to compare whites and East Asians educated in the same school system. Arthur Jensen and his then-student Patricia Whang published an interesting series of papers (not available online) about ten years ago that came close to doing this. They compared a sample of white children from an above-average-SES Bay Area suburb to a sample of Chinese children of below-average SES from Oakland’s Chinatown. They administered to both samples Raven’s Standard Progressive Matrices (SPM), which is a nonverbal test of inductive reasoning, and a reaction-time task that they called the Math Verification Test (MVT). In each trial of the MVT, some arithmetic statement was flashed on a computer screen: 2 + 5 = 7, 9 – 4 = 6, 4 × 2 = 8, and so on. If the statement was correct, the subject pressed a button marked YES as quickly as possible; if it was incorrect, a button marked NO.

The Chinese children showed a mean advantage on the SPM of 0.3 SD (about 5 IQ points). That is quite typical of the white-East Asian IQ gap found worldwide across several recent studies. The Chinese children also showed faster reaction times in the MVT, but Jensen and Whang argued that their advantage over the white children exceeding 0.4 SD was greater than would have been expected on the basis of their edge in SPM scores alone. Within both groups SPM scores were negatively correlated with MVT reaction times.

We can imagine that the Chinese children have an advantage in g (evidenced by their higher SPM scores) that accounts for some portion of their superior performance on the MVT. Perhaps the remainder of the gap is accounted for by some factor particular to the processing of numerical stimuli. To investigate this possibility, Jensen and Whang administered a standardized test of school achievement in mathematics (MAT) to their Chinese sample. MVT reaction times were even more negatively correlated with MAT scores than with SPM scores. The semipartial correlations between the MAT and the MVT variables with the influence of the SPM removed from the MAT were still significant. The semipartial correlations between the SPM and the MVT variables with the influence of the MAT removed from the SPM, however, were near zero and not significant. These observations can be accounted for by the following model: the SPM measures only g, while both the MAT and MVT measure a numerical factor in addition to g. The shorter MVT reaction times by the Chinese children are then accounted for by higher standings on both g and this numerical (spatial?) factor.

Here a plausible case can be made for how a greater facility with visual or analogical representations might increase processing efficiency. In a later book chapter, Jensen describes a series of studies conducted in the seventies revealing the algorithm by which people perform simple addition in their heads. Subjects were seated in front of a computer screen and a console with nine response buttons marked 1, 2, 3, and so on. Each stimulus consisted of a simple addition problem: 2 + 5 = ?, 4 + 4 = ?, 6 + 3 = ?, and so on. The subjects simply had to press the button corresponding to the correct problem as quickly as possible. It was found that reaction time averaged across subjects increased as a linear function of the magnitude of the smaller addend as long as the addends were not equal. If the addends were equal, reaction time did not vary with the magnitudes of the addends and tended to be shorter overall. These observations can be accounted for by something like the following model: the subject conjures up a mental number line, zooms in on a tick mark corresponding to the larger addend, moves n ticks to the right where n is the magnitude of the smaller addend, and reads off the digit label under that particular tick mark. If the addends are equal, the subject simply recalls the answer from memory. Other models are possi
ble, but it seems that they must all invoke analogical representation. This effect of addend size on reaction time was observed in a wide age range, from first graders to college students; the latter averaged a reaction time one-fourth as large as that averaged by first graders, but apparently both groups and everyone in between were executing the same algorithm. Note that this simple task is very similar to the addition portion of the MVT administered by Jensen and Whang. Jensen does not say whether the effect of addend size was borne out in his own study; perhaps there was not enough data to permit the proper analysis. (For what it’s worth, I heard a neuropsych talk recently where it was reported that hemispatial neglect patients tend to overestimate the average the two numbers, as if they were “looking” too much at the right side of a mental number line.)

Is the advantage of the Chinese children attributable to a greater reliance on analogical representation enabled by superior spatial-visualization ability? If so, does this cascade up to the higher-level differences observed in tests such as the SAT-M? Regardless of whether causation is genetic or cultural or some combination thereof, this possibility is worth pursuing. Certainly the mystery of the differences in mental abilities between whites and East Asians is worth tackling in any way that we can.

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